<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/i2c, branch vsnprintf</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>i2c: riic: Always round-up when calculating bus period</title>
<updated>2024-12-12T11:54:02+00:00</updated>
<author>
<name>Geert Uytterhoeven</name>
<email>geert+renesas@glider.be</email>
</author>
<published>2024-11-22T14:14:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=de6b43798d9043a7c749a0428dbb02d5fff156e5'/>
<id>de6b43798d9043a7c749a0428dbb02d5fff156e5</id>
<content type='text'>
Currently, the RIIC driver may run the I2C bus faster than requested,
which may cause subtle failures.  E.g. Biju reported a measured bus
speed of 450 kHz instead of the expected maximum of 400 kHz on RZ/G2L.

The initial calculation of the bus period uses DIV_ROUND_UP(), to make
sure the actual bus speed never becomes faster than the requested bus
speed.  However, the subsequent division-by-two steps do not use
round-up, which may lead to a too-small period, hence a too-fast and
possible out-of-spec bus speed.  E.g. on RZ/Five, requesting a bus speed
of 100 resp. 400 kHz will yield too-fast target bus speeds of 100806
resp. 403226 Hz instead of 97656 resp. 390625 Hz.

Fix this by using DIV_ROUND_UP() in the subsequent divisions, too.

Tested on RZ/A1H, RZ/A2M, and RZ/Five.

Fixes: d982d66514192cdb ("i2c: riic: remove clock and frequency restrictions")
Reported-by: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Cc: &lt;stable@vger.kernel.org&gt; # v4.15+
Link: https://lore.kernel.org/r/c59aea77998dfea1b4456c4b33b55ab216fcbf5e.1732284746.git.geert+renesas@glider.be
Signed-off-by: Andi Shyti &lt;andi.shyti@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently, the RIIC driver may run the I2C bus faster than requested,
which may cause subtle failures.  E.g. Biju reported a measured bus
speed of 450 kHz instead of the expected maximum of 400 kHz on RZ/G2L.

The initial calculation of the bus period uses DIV_ROUND_UP(), to make
sure the actual bus speed never becomes faster than the requested bus
speed.  However, the subsequent division-by-two steps do not use
round-up, which may lead to a too-small period, hence a too-fast and
possible out-of-spec bus speed.  E.g. on RZ/Five, requesting a bus speed
of 100 resp. 400 kHz will yield too-fast target bus speeds of 100806
resp. 403226 Hz instead of 97656 resp. 390625 Hz.

Fix this by using DIV_ROUND_UP() in the subsequent divisions, too.

Tested on RZ/A1H, RZ/A2M, and RZ/Five.

Fixes: d982d66514192cdb ("i2c: riic: remove clock and frequency restrictions")
Reported-by: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Cc: &lt;stable@vger.kernel.org&gt; # v4.15+
Link: https://lore.kernel.org/r/c59aea77998dfea1b4456c4b33b55ab216fcbf5e.1732284746.git.geert+renesas@glider.be
Signed-off-by: Andi Shyti &lt;andi.shyti@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>i2c: nomadik: Add missing sentinel to match table</title>
<updated>2024-12-10T15:07:53+00:00</updated>
<author>
<name>Geert Uytterhoeven</name>
<email>geert+renesas@glider.be</email>
</author>
<published>2024-12-06T08:28:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5751eee5c620c7e47a277ca929c4010caf24654c'/>
<id>5751eee5c620c7e47a277ca929c4010caf24654c</id>
<content type='text'>
The OF match table is not NULL-terminated.
Fix this by adding a sentinel to nmk_i2c_eyeq_match_table[].

Fixes: a0d15cc47f29be6d ("i2c: nomadik: switch from of_device_is_compatible() to of_match_device()")
Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Reviewed-by: Théo Lebrun &lt;theo.lebrun@bootlin.com&gt;
Signed-off-by: Andi Shyti &lt;andi.shyti@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The OF match table is not NULL-terminated.
Fix this by adding a sentinel to nmk_i2c_eyeq_match_table[].

Fixes: a0d15cc47f29be6d ("i2c: nomadik: switch from of_device_is_compatible() to of_match_device()")
Signed-off-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
Reviewed-by: Théo Lebrun &lt;theo.lebrun@bootlin.com&gt;
Signed-off-by: Andi Shyti &lt;andi.shyti@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>i2c: pnx: Fix timeout in wait functions</title>
<updated>2024-12-10T14:50:50+00:00</updated>
<author>
<name>Vladimir Riabchun</name>
<email>ferr.lambarginio@gmail.com</email>
</author>
<published>2024-12-06T23:19:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7363f2d4c18557c99c536b70489187bb4e05c412'/>
<id>7363f2d4c18557c99c536b70489187bb4e05c412</id>
<content type='text'>
Since commit f63b94be6942 ("i2c: pnx: Fix potential deadlock warning
from del_timer_sync() call in isr") jiffies are stored in
i2c_pnx_algo_data.timeout, but wait_timeout and wait_reset are still
using it as milliseconds. Convert jiffies back to milliseconds to wait
for the expected amount of time.

Fixes: f63b94be6942 ("i2c: pnx: Fix potential deadlock warning from del_timer_sync() call in isr")
Signed-off-by: Vladimir Riabchun &lt;ferr.lambarginio@gmail.com&gt;
Signed-off-by: Andi Shyti &lt;andi.shyti@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Since commit f63b94be6942 ("i2c: pnx: Fix potential deadlock warning
from del_timer_sync() call in isr") jiffies are stored in
i2c_pnx_algo_data.timeout, but wait_timeout and wait_reset are still
using it as milliseconds. Convert jiffies back to milliseconds to wait
for the expected amount of time.

Fixes: f63b94be6942 ("i2c: pnx: Fix potential deadlock warning from del_timer_sync() call in isr")
Signed-off-by: Vladimir Riabchun &lt;ferr.lambarginio@gmail.com&gt;
Signed-off-by: Andi Shyti &lt;andi.shyti@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>module: Convert default symbol namespace to string literal</title>
<updated>2024-12-03T16:22:25+00:00</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2024-12-03T10:21:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ceb8bf2ceaa77fe222fe8fe32cb7789c9099ddf1'/>
<id>ceb8bf2ceaa77fe222fe8fe32cb7789c9099ddf1</id>
<content type='text'>
Commit cdd30ebb1b9f ("module: Convert symbol namespace to string
literal") only converted MODULE_IMPORT_NS() and EXPORT_SYMBOL_NS(),
leaving DEFAULT_SYMBOL_NAMESPACE as a macro expansion.

This commit converts DEFAULT_SYMBOL_NAMESPACE in the same way to avoid
annoyance for the default namespace as well.

Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Reviewed-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit cdd30ebb1b9f ("module: Convert symbol namespace to string
literal") only converted MODULE_IMPORT_NS() and EXPORT_SYMBOL_NS(),
leaving DEFAULT_SYMBOL_NAMESPACE as a macro expansion.

This commit converts DEFAULT_SYMBOL_NAMESPACE in the same way to avoid
annoyance for the default namespace as well.

Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Reviewed-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>module: Convert symbol namespace to string literal</title>
<updated>2024-12-02T19:34:44+00:00</updated>
<author>
<name>Peter Zijlstra</name>
<email>peterz@infradead.org</email>
</author>
<published>2024-12-02T14:59:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cdd30ebb1b9f36159d66f088b61aee264e649d7a'/>
<id>cdd30ebb1b9f36159d66f088b61aee264e649d7a</id>
<content type='text'>
Clean up the existing export namespace code along the same lines of
commit 33def8498fdd ("treewide: Convert macro and uses of __section(foo)
to __section("foo")") and for the same reason, it is not desired for the
namespace argument to be a macro expansion itself.

Scripted using

  git grep -l -e MODULE_IMPORT_NS -e EXPORT_SYMBOL_NS | while read file;
  do
    awk -i inplace '
      /^#define EXPORT_SYMBOL_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /^#define MODULE_IMPORT_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /MODULE_IMPORT_NS/ {
        $0 = gensub(/MODULE_IMPORT_NS\(([^)]*)\)/, "MODULE_IMPORT_NS(\"\\1\")", "g");
      }
      /EXPORT_SYMBOL_NS/ {
        if ($0 ~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+),/) {
  	if ($0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/ &amp;&amp;
  	    $0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(\)/ &amp;&amp;
  	    $0 !~ /^my/) {
  	  getline line;
  	  gsub(/[[:space:]]*\\$/, "");
  	  gsub(/[[:space:]]/, "", line);
  	  $0 = $0 " " line;
  	}

  	$0 = gensub(/(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/,
  		    "\\1(\\2, \"\\3\")", "g");
        }
      }
      { print }' $file;
  done

Requested-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://mail.google.com/mail/u/2/#inbox/FMfcgzQXKWgMmjdFwwdsfgxzKpVHWPlc
Acked-by: Greg KH &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Clean up the existing export namespace code along the same lines of
commit 33def8498fdd ("treewide: Convert macro and uses of __section(foo)
to __section("foo")") and for the same reason, it is not desired for the
namespace argument to be a macro expansion itself.

Scripted using

  git grep -l -e MODULE_IMPORT_NS -e EXPORT_SYMBOL_NS | while read file;
  do
    awk -i inplace '
      /^#define EXPORT_SYMBOL_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /^#define MODULE_IMPORT_NS/ {
        gsub(/__stringify\(ns\)/, "ns");
        print;
        next;
      }
      /MODULE_IMPORT_NS/ {
        $0 = gensub(/MODULE_IMPORT_NS\(([^)]*)\)/, "MODULE_IMPORT_NS(\"\\1\")", "g");
      }
      /EXPORT_SYMBOL_NS/ {
        if ($0 ~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+),/) {
  	if ($0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/ &amp;&amp;
  	    $0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(\)/ &amp;&amp;
  	    $0 !~ /^my/) {
  	  getline line;
  	  gsub(/[[:space:]]*\\$/, "");
  	  gsub(/[[:space:]]/, "", line);
  	  $0 = $0 " " line;
  	}

  	$0 = gensub(/(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/,
  		    "\\1(\\2, \"\\3\")", "g");
        }
      }
      { print }' $file;
  done

Requested-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Link: https://mail.google.com/mail/u/2/#inbox/FMfcgzQXKWgMmjdFwwdsfgxzKpVHWPlc
Acked-by: Greg KH &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Get rid of 'remove_new' relic from platform driver struct</title>
<updated>2024-12-01T23:12:43+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-12-01T23:12:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=e70140ba0d2b1a30467d4af6bcfe761327b9ec95'/>
<id>e70140ba0d2b1a30467d4af6bcfe761327b9ec95</id>
<content type='text'>
The continual trickle of small conversion patches is grating on me, and
is really not helping.  Just get rid of the 'remove_new' member
function, which is just an alias for the plain 'remove', and had a
comment to that effect:

  /*
   * .remove_new() is a relic from a prototype conversion of .remove().
   * New drivers are supposed to implement .remove(). Once all drivers are
   * converted to not use .remove_new any more, it will be dropped.
   */

This was just a tree-wide 'sed' script that replaced '.remove_new' with
'.remove', with some care taken to turn a subsequent tab into two tabs
to make things line up.

I did do some minimal manual whitespace adjustment for places that used
spaces to line things up.

Then I just removed the old (sic) .remove_new member function, and this
is the end result.  No more unnecessary conversion noise.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The continual trickle of small conversion patches is grating on me, and
is really not helping.  Just get rid of the 'remove_new' member
function, which is just an alias for the plain 'remove', and had a
comment to that effect:

  /*
   * .remove_new() is a relic from a prototype conversion of .remove().
   * New drivers are supposed to implement .remove(). Once all drivers are
   * converted to not use .remove_new any more, it will be dropped.
   */

This was just a tree-wide 'sed' script that replaced '.remove_new' with
'.remove', with some care taken to turn a subsequent tab into two tabs
to make things line up.

I did do some minimal manual whitespace adjustment for places that used
spaces to line things up.

Then I just removed the old (sic) .remove_new member function, and this
is the end result.  No more unnecessary conversion noise.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>i2c: Fix whitespace style issue</title>
<updated>2024-11-27T11:23:43+00:00</updated>
<author>
<name>Liam Zuiderhoek</name>
<email>zuiderhoekl@gmail.com</email>
</author>
<published>2024-10-22T18:46:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=44b682694a0ca366bf15c26c3c3c16d26c9e9f6d'/>
<id>44b682694a0ca366bf15c26c3c3c16d26c9e9f6d</id>
<content type='text'>
This patch fixes a coding style issue in the alignment of parameters
in the function i2c_smbus_write_bytes(). It replaces spaces with tabs for
alignment,  as per the coding style guidelines.

Signed-off-by: Liam Zuiderhoek &lt;zuiderhoekl@gmail.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch fixes a coding style issue in the alignment of parameters
in the function i2c_smbus_write_bytes(). It replaces spaces with tabs for
alignment,  as per the coding style guidelines.

Signed-off-by: Liam Zuiderhoek &lt;zuiderhoekl@gmail.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>i2c: of-prober: Add GPIO support to simple helpers</title>
<updated>2024-11-27T11:04:26+00:00</updated>
<author>
<name>Chen-Yu Tsai</name>
<email>wenst@chromium.org</email>
</author>
<published>2024-11-06T09:33:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=39b415f84654892003cebb7c026b7daa3380610b'/>
<id>39b415f84654892003cebb7c026b7daa3380610b</id>
<content type='text'>
Add GPIO support to the simple helpers for the I2C OF component prober.
Components that the prober intends to probe likely require their
regulator supplies be enabled, and GPIOs be toggled to enable them or
bring them out of reset before they will respond to probe attempts.
Regulator supplies were handled in the previous patch.

The assumption is that the same class of components to be probed are
always connected in the same fashion with the same regulator supply
and GPIO. The names may vary due to binding differences, but the
physical layout does not change.

This supports at most one GPIO pin. The user must specify the GPIO name,
the polarity, and the amount of time to wait after the GPIO is toggled.
Devices with more than one GPIO pin likely require specific power
sequencing beyond what generic code can easily support.

Signed-off-by: Chen-Yu Tsai &lt;wenst@chromium.org&gt;
Reviewed-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Reviewed-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Tested-by: Andrey Skvortsov &lt;andrej.skvortzov@gmail.com&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add GPIO support to the simple helpers for the I2C OF component prober.
Components that the prober intends to probe likely require their
regulator supplies be enabled, and GPIOs be toggled to enable them or
bring them out of reset before they will respond to probe attempts.
Regulator supplies were handled in the previous patch.

The assumption is that the same class of components to be probed are
always connected in the same fashion with the same regulator supply
and GPIO. The names may vary due to binding differences, but the
physical layout does not change.

This supports at most one GPIO pin. The user must specify the GPIO name,
the polarity, and the amount of time to wait after the GPIO is toggled.
Devices with more than one GPIO pin likely require specific power
sequencing beyond what generic code can easily support.

Signed-off-by: Chen-Yu Tsai &lt;wenst@chromium.org&gt;
Reviewed-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Reviewed-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Tested-by: Andrey Skvortsov &lt;andrej.skvortzov@gmail.com&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>i2c: of-prober: Add simple helpers for regulator support</title>
<updated>2024-11-27T11:04:18+00:00</updated>
<author>
<name>Chen-Yu Tsai</name>
<email>wenst@chromium.org</email>
</author>
<published>2024-11-06T09:33:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=897261149d255d03fc90bec6782e3835cacbfdde'/>
<id>897261149d255d03fc90bec6782e3835cacbfdde</id>
<content type='text'>
Add helpers to do regulator management for the I2C OF component prober.
Components that the prober intends to probe likely require their
regulator supplies be enabled, and GPIOs be toggled to enable them or
bring them out of reset before they will respond to probe attempts.
GPIOs will be handled in the next patch.

The assumption is that the same class of components to be probed are
always connected in the same fashion with the same regulator supply
and GPIO. The names may vary due to binding differences, but the
physical layout does not change.

This set of helpers supports at most one regulator supply. The user
must specify the node from which the supply is retrieved. The supply
name and the amount of time to wait after the supply is enabled are
also given by the user.

Signed-off-by: Chen-Yu Tsai &lt;wenst@chromium.org&gt;
Reviewed-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Reviewed-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add helpers to do regulator management for the I2C OF component prober.
Components that the prober intends to probe likely require their
regulator supplies be enabled, and GPIOs be toggled to enable them or
bring them out of reset before they will respond to probe attempts.
GPIOs will be handled in the next patch.

The assumption is that the same class of components to be probed are
always connected in the same fashion with the same regulator supply
and GPIO. The names may vary due to binding differences, but the
physical layout does not change.

This set of helpers supports at most one regulator supply. The user
must specify the node from which the supply is retrieved. The supply
name and the amount of time to wait after the supply is enabled are
also given by the user.

Signed-off-by: Chen-Yu Tsai &lt;wenst@chromium.org&gt;
Reviewed-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Reviewed-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>i2c: Introduce OF component probe function</title>
<updated>2024-11-27T11:04:10+00:00</updated>
<author>
<name>Chen-Yu Tsai</name>
<email>wenst@chromium.org</email>
</author>
<published>2024-11-06T09:33:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=157ce8f381efe264933e9366db828d845bade3a1'/>
<id>157ce8f381efe264933e9366db828d845bade3a1</id>
<content type='text'>
Some devices are designed and manufactured with some components having
multiple drop-in replacement options. These components are often
connected to the mainboard via ribbon cables, having the same signals
and pin assignments across all options. These may include the display
panel and touchscreen on laptops and tablets, and the trackpad on
laptops. Sometimes which component option is used in a particular device
can be detected by some firmware provided identifier, other times that
information is not available, and the kernel has to try to probe each
device.

This change attempts to make the "probe each device" case cleaner. The
current approach is to have all options added and enabled in the device
tree. The kernel would then bind each device and run each driver's probe
function. This works, but has been broken before due to the introduction
of asynchronous probing, causing multiple instances requesting "shared"
resources, such as pinmuxes, GPIO pins, interrupt lines, at the same
time, with only one instance succeeding. Work arounds for these include
moving the pinmux to the parent I2C controller, using GPIO hogs or
pinmux settings to keep the GPIO pins in some fixed configuration, and
requesting the interrupt line very late. Such configurations can be seen
on the MT8183 Krane Chromebook tablets, and the Qualcomm sc8280xp-based
Lenovo Thinkpad 13S.

Instead of this delicate dance between drivers and device tree quirks,
this change introduces a simple I2C component probe function. For a
given class of devices on the same I2C bus, it will go through all of
them, doing a simple I2C read transfer and see which one of them responds.
It will then enable the device that responds.

This requires some minor modifications in the existing device tree. The
status for all the device nodes for the component options must be set
to "fail-needs-probe". This makes it clear that some mechanism is
needed to enable one of them, and also prevents the prober and device
drivers running at the same time.

Signed-off-by: Chen-Yu Tsai &lt;wenst@chromium.org&gt;
Reviewed-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Reviewed-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
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<pre>
Some devices are designed and manufactured with some components having
multiple drop-in replacement options. These components are often
connected to the mainboard via ribbon cables, having the same signals
and pin assignments across all options. These may include the display
panel and touchscreen on laptops and tablets, and the trackpad on
laptops. Sometimes which component option is used in a particular device
can be detected by some firmware provided identifier, other times that
information is not available, and the kernel has to try to probe each
device.

This change attempts to make the "probe each device" case cleaner. The
current approach is to have all options added and enabled in the device
tree. The kernel would then bind each device and run each driver's probe
function. This works, but has been broken before due to the introduction
of asynchronous probing, causing multiple instances requesting "shared"
resources, such as pinmuxes, GPIO pins, interrupt lines, at the same
time, with only one instance succeeding. Work arounds for these include
moving the pinmux to the parent I2C controller, using GPIO hogs or
pinmux settings to keep the GPIO pins in some fixed configuration, and
requesting the interrupt line very late. Such configurations can be seen
on the MT8183 Krane Chromebook tablets, and the Qualcomm sc8280xp-based
Lenovo Thinkpad 13S.

Instead of this delicate dance between drivers and device tree quirks,
this change introduces a simple I2C component probe function. For a
given class of devices on the same I2C bus, it will go through all of
them, doing a simple I2C read transfer and see which one of them responds.
It will then enable the device that responds.

This requires some minor modifications in the existing device tree. The
status for all the device nodes for the component options must be set
to "fail-needs-probe". This makes it clear that some mechanism is
needed to enable one of them, and also prevents the prober and device
drivers running at the same time.

Signed-off-by: Chen-Yu Tsai &lt;wenst@chromium.org&gt;
Reviewed-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Reviewed-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Wolfram Sang &lt;wsa+renesas@sang-engineering.com&gt;
</pre>
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