<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/spi, branch v5.4.244</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>spi: fsl-cpm: Use 16 bit mode for large transfers with even size</title>
<updated>2023-05-30T11:44:08+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@csgroup.eu</email>
</author>
<published>2023-05-15T14:07:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b558275c1b040f0e5aa56c862241f9212b6118c3'/>
<id>b558275c1b040f0e5aa56c862241f9212b6118c3</id>
<content type='text'>
(cherry picked from upstream fc96ec826bced75cc6b9c07a4ac44bbf651337ab)

On CPM, the RISC core is a lot more efficiant when doing transfers
in 16-bits chunks than in 8-bits chunks, but unfortunately the
words need to be byte swapped as seen in a previous commit.

So, for large tranfers with an even size, allocate a temporary tx
buffer and byte-swap data before and after transfer.

This change allows setting higher speed for transfer. For instance
on an MPC 8xx (CPM1 comms RISC processor), the documentation tells
that transfer in byte mode at 1 kbit/s uses 0.200% of CPM load
at 25 MHz while a word transfer at the same speed uses 0.032%
of CPM load. This means the speed can be 6 times higher in
word mode for the same CPM load.

For the time being, only do it on CPM1 as there must be a
trade-off between the CPM load reduction and the CPU load required
to byte swap the data.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Link: https://lore.kernel.org/r/f2e981f20f92dd28983c3949702a09248c23845c.1680371809.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
(cherry picked from upstream fc96ec826bced75cc6b9c07a4ac44bbf651337ab)

On CPM, the RISC core is a lot more efficiant when doing transfers
in 16-bits chunks than in 8-bits chunks, but unfortunately the
words need to be byte swapped as seen in a previous commit.

So, for large tranfers with an even size, allocate a temporary tx
buffer and byte-swap data before and after transfer.

This change allows setting higher speed for transfer. For instance
on an MPC 8xx (CPM1 comms RISC processor), the documentation tells
that transfer in byte mode at 1 kbit/s uses 0.200% of CPM load
at 25 MHz while a word transfer at the same speed uses 0.032%
of CPM load. This means the speed can be 6 times higher in
word mode for the same CPM load.

For the time being, only do it on CPM1 as there must be a
trade-off between the CPM load reduction and the CPU load required
to byte swap the data.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Link: https://lore.kernel.org/r/f2e981f20f92dd28983c3949702a09248c23845c.1680371809.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: fsl-spi: Re-organise transfer bits_per_word adaptation</title>
<updated>2023-05-30T11:44:08+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@csgroup.eu</email>
</author>
<published>2023-05-15T14:07:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d64a45c019acd361dff40b207e39bd44832eed55'/>
<id>d64a45c019acd361dff40b207e39bd44832eed55</id>
<content type='text'>
(backported from upstream 8a5299a1278eadf1e08a598a5345c376206f171e)

For different reasons, fsl-spi driver performs bits_per_word
modifications for different reasons:
- On CPU mode, to minimise amount of interrupts
- On CPM/QE mode to work around controller byte order

For CPU mode that's done in fsl_spi_prepare_message() while
for CPM mode that's done in fsl_spi_setup_transfer().

Reunify all of it in fsl_spi_prepare_message(), and catch
impossible cases early through master's bits_per_word_mask
instead of returning EINVAL later.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Link: https://lore.kernel.org/r/0ce96fe96e8b07cba0613e4097cfd94d09b8919a.1680371809.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
(backported from upstream 8a5299a1278eadf1e08a598a5345c376206f171e)

For different reasons, fsl-spi driver performs bits_per_word
modifications for different reasons:
- On CPU mode, to minimise amount of interrupts
- On CPM/QE mode to work around controller byte order

For CPU mode that's done in fsl_spi_prepare_message() while
for CPM mode that's done in fsl_spi_setup_transfer().

Reunify all of it in fsl_spi_prepare_message(), and catch
impossible cases early through master's bits_per_word_mask
instead of returning EINVAL later.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Link: https://lore.kernel.org/r/0ce96fe96e8b07cba0613e4097cfd94d09b8919a.1680371809.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: spi-imx: fix MX51_ECSPI_* macros when cs &gt; 3</title>
<updated>2023-05-30T11:44:03+00:00</updated>
<author>
<name>Kevin Groeneveld</name>
<email>kgroeneveld@lenbrook.com</email>
</author>
<published>2023-03-18T22:21:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d3f32dc2ccc25668abc8d121f06ca3c4b19cf1b1'/>
<id>d3f32dc2ccc25668abc8d121f06ca3c4b19cf1b1</id>
<content type='text'>
[ Upstream commit 87c614175bbf28d3fd076dc2d166bac759e41427 ]

When using gpio based chip select the cs value can go outside the range
0 – 3. The various MX51_ECSPI_* macros did not take this into consideration
resulting in possible corruption of the configuration.

For example for any cs value over 3 the SCLKPHA bits would not be set and
other values in the register possibly corrupted.

One way to fix this is to just mask the cs bits to 2 bits. This still
allows all 4 native chip selects to work as well as gpio chip selects
(which can use any of the 4 chip select configurations).

Signed-off-by: Kevin Groeneveld &lt;kgroeneveld@lenbrook.com&gt;
Link: https://lore.kernel.org/r/20230318222132.3373-1-kgroeneveld@lenbrook.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 87c614175bbf28d3fd076dc2d166bac759e41427 ]

When using gpio based chip select the cs value can go outside the range
0 – 3. The various MX51_ECSPI_* macros did not take this into consideration
resulting in possible corruption of the configuration.

For example for any cs value over 3 the SCLKPHA bits would not be set and
other values in the register possibly corrupted.

One way to fix this is to just mask the cs bits to 2 bits. This still
allows all 4 native chip selects to work as well as gpio chip selects
(which can use any of the 4 chip select configurations).

Signed-off-by: Kevin Groeneveld &lt;kgroeneveld@lenbrook.com&gt;
Link: https://lore.kernel.org/r/20230318222132.3373-1-kgroeneveld@lenbrook.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: fsl-spi: Fix CPM/QE mode Litte Endian</title>
<updated>2023-05-17T09:35:47+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@csgroup.eu</email>
</author>
<published>2023-04-01T17:59:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=170e223240520b284899011b94cbdd48f9e1ad8e'/>
<id>170e223240520b284899011b94cbdd48f9e1ad8e</id>
<content type='text'>
[ Upstream commit c20c57d9868d7f9fd1b2904c7801b07e128f6322 ]

CPM has the same problem as QE so for CPM also use the fix added
by commit 0398fb70940e ("spi/spi_mpc8xxx: Fix QE mode Litte Endian"):

  CPM mode uses Little Endian so words &gt; 8 bits are byte swapped.
  Workaround this by always enforcing wordsize 8 for 16 and 32 bits
  words. Unfortunately this will not work for LSB transfers
  where wordsize is &gt; 8 bits so disable these for now.

Also limit the workaround to 16 and 32 bits words because it can
only work for multiples of 8-bits.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Joakim Tjernlund &lt;Joakim.Tjernlund@infinera.com&gt;
Fixes: 0398fb70940e ("spi/spi_mpc8xxx: Fix QE mode Litte Endian")
Link: https://lore.kernel.org/r/1b7d3e84b1128f42c1887dd2fb9cdf390f541bc1.1680371809.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit c20c57d9868d7f9fd1b2904c7801b07e128f6322 ]

CPM has the same problem as QE so for CPM also use the fix added
by commit 0398fb70940e ("spi/spi_mpc8xxx: Fix QE mode Litte Endian"):

  CPM mode uses Little Endian so words &gt; 8 bits are byte swapped.
  Workaround this by always enforcing wordsize 8 for 16 and 32 bits
  words. Unfortunately this will not work for LSB transfers
  where wordsize is &gt; 8 bits so disable these for now.

Also limit the workaround to 16 and 32 bits words because it can
only work for multiples of 8-bits.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Joakim Tjernlund &lt;Joakim.Tjernlund@infinera.com&gt;
Fixes: 0398fb70940e ("spi/spi_mpc8xxx: Fix QE mode Litte Endian")
Link: https://lore.kernel.org/r/1b7d3e84b1128f42c1887dd2fb9cdf390f541bc1.1680371809.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: qup: Don't skip cleanup in remove's error path</title>
<updated>2023-05-17T09:35:47+00:00</updated>
<author>
<name>Uwe Kleine-König</name>
<email>u.kleine-koenig@pengutronix.de</email>
</author>
<published>2023-03-30T21:03:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8632384337038b97910c2f7bb5a3f377aa68d001'/>
<id>8632384337038b97910c2f7bb5a3f377aa68d001</id>
<content type='text'>
[ Upstream commit 61f49171a43ab1f80c73c5c88c508770c461e0f2 ]

Returning early in a platform driver's remove callback is wrong. In this
case the dma resources are not released in the error path. this is never
retried later and so this is a permanent leak. To fix this, only skip
hardware disabling if waking the device fails.

Fixes: 64ff247a978f ("spi: Add Qualcomm QUP SPI controller support")
Signed-off-by: Uwe Kleine-König &lt;u.kleine-koenig@pengutronix.de&gt;
Link: https://lore.kernel.org/r/20230330210341.2459548-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 61f49171a43ab1f80c73c5c88c508770c461e0f2 ]

Returning early in a platform driver's remove callback is wrong. In this
case the dma resources are not released in the error path. this is never
retried later and so this is a permanent leak. To fix this, only skip
hardware disabling if waking the device fails.

Fixes: 64ff247a978f ("spi: Add Qualcomm QUP SPI controller support")
Signed-off-by: Uwe Kleine-König &lt;u.kleine-koenig@pengutronix.de&gt;
Link: https://lore.kernel.org/r/20230330210341.2459548-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: synquacer: Fix timeout handling in synquacer_spi_transfer_one()</title>
<updated>2023-03-11T15:43:47+00:00</updated>
<author>
<name>Christophe JAILLET</name>
<email>christophe.jaillet@wanadoo.fr</email>
</author>
<published>2023-02-15T13:01:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d6250e00bf423f1e7ea9b866edeff21943df4916'/>
<id>d6250e00bf423f1e7ea9b866edeff21943df4916</id>
<content type='text'>
[ Upstream commit e6a0b671880207566e1ece983bf989dde60bc1d7 ]

wait_for_completion_timeout() never returns a &lt;0 value. It returns either
on timeout or a positive value (at least 1, or number of jiffies left
till timeout)

So, fix the error handling path and return -ETIMEDOUT should a timeout
occur.

Fixes: b0823ee35cf9 ("spi: Add spi driver for Socionext SynQuacer platform")
Signed-off-by: Christophe JAILLET &lt;christophe.jaillet@wanadoo.fr&gt;
Acked-by: Jassi Brar &lt;jaswinder.singh@linaro.org&gt;
Link: https://lore.kernel.org/r/c2040bf3cfa201fd8890cfab14fa5a701ffeca14.1676466072.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit e6a0b671880207566e1ece983bf989dde60bc1d7 ]

wait_for_completion_timeout() never returns a &lt;0 value. It returns either
on timeout or a positive value (at least 1, or number of jiffies left
till timeout)

So, fix the error handling path and return -ETIMEDOUT should a timeout
occur.

Fixes: b0823ee35cf9 ("spi: Add spi driver for Socionext SynQuacer platform")
Signed-off-by: Christophe JAILLET &lt;christophe.jaillet@wanadoo.fr&gt;
Acked-by: Jassi Brar &lt;jaswinder.singh@linaro.org&gt;
Link: https://lore.kernel.org/r/c2040bf3cfa201fd8890cfab14fa5a701ffeca14.1676466072.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: bcm63xx-hsspi: Fix multi-bit mode setting</title>
<updated>2023-03-11T15:43:47+00:00</updated>
<author>
<name>William Zhang</name>
<email>william.zhang@broadcom.com</email>
</author>
<published>2023-02-09T20:02:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=870a0f519ac29f52febfeb4533b1f1fbd9e89fb3'/>
<id>870a0f519ac29f52febfeb4533b1f1fbd9e89fb3</id>
<content type='text'>
[ Upstream commit 811ff802aaf878ebbbaeac0307a0164fa21e7d40 ]

Currently the driver always sets the controller to dual data bit mode
for both tx and rx data in the profile mode control register even for
single data bit transfer. Luckily the opcode is set correctly according
to SPI transfer data bit width so it does not actually cause issues.

This change fixes the problem by setting tx and rx data bit mode field
correctly according to the actual SPI transfer tx and rx data bit width.

Fixes: 142168eba9dc ("spi: bcm63xx-hsspi: add bcm63xx HSSPI driver")
Signed-off-by: William Zhang &lt;william.zhang@broadcom.com&gt;
Link: https://lore.kernel.org/r/20230209200246.141520-11-william.zhang@broadcom.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 811ff802aaf878ebbbaeac0307a0164fa21e7d40 ]

Currently the driver always sets the controller to dual data bit mode
for both tx and rx data in the profile mode control register even for
single data bit transfer. Luckily the opcode is set correctly according
to SPI transfer data bit width so it does not actually cause issues.

This change fixes the problem by setting tx and rx data bit mode field
correctly according to the actual SPI transfer tx and rx data bit width.

Fixes: 142168eba9dc ("spi: bcm63xx-hsspi: add bcm63xx HSSPI driver")
Signed-off-by: William Zhang &lt;william.zhang@broadcom.com&gt;
Link: https://lore.kernel.org/r/20230209200246.141520-11-william.zhang@broadcom.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: bcm63xx-hsspi: fix pm_runtime</title>
<updated>2023-03-11T15:43:47+00:00</updated>
<author>
<name>Álvaro Fernández Rojas</name>
<email>noltari@gmail.com</email>
</author>
<published>2021-02-23T15:18:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=dd271f1798068804418875aeea9c3f8d06c429ba'/>
<id>dd271f1798068804418875aeea9c3f8d06c429ba</id>
<content type='text'>
[ Upstream commit 216e8e80057a9f0b6366327881acf88eaf9f1fd4 ]

The driver sets auto_runtime_pm to true, but it doesn't call
pm_runtime_enable(), which results in "Failed to power device" when PM support
is enabled.

Signed-off-by: Álvaro Fernández Rojas &lt;noltari@gmail.com&gt;
Link: https://lore.kernel.org/r/20210223151851.4110-3-noltari@gmail.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Stable-dep-of: 811ff802aaf8 ("spi: bcm63xx-hsspi: Fix multi-bit mode setting")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 216e8e80057a9f0b6366327881acf88eaf9f1fd4 ]

The driver sets auto_runtime_pm to true, but it doesn't call
pm_runtime_enable(), which results in "Failed to power device" when PM support
is enabled.

Signed-off-by: Álvaro Fernández Rojas &lt;noltari@gmail.com&gt;
Link: https://lore.kernel.org/r/20210223151851.4110-3-noltari@gmail.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Stable-dep-of: 811ff802aaf8 ("spi: bcm63xx-hsspi: Fix multi-bit mode setting")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: spidev: remove debug messages that access spidev-&gt;spi without locking</title>
<updated>2023-02-06T06:52:41+00:00</updated>
<author>
<name>Bartosz Golaszewski</name>
<email>bartosz.golaszewski@linaro.org</email>
</author>
<published>2023-01-06T10:07:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=dc0867c4472214934f3a4dcb9367f97240dc8fb4'/>
<id>dc0867c4472214934f3a4dcb9367f97240dc8fb4</id>
<content type='text'>
[ Upstream commit 6b35b173dbc1711f8d272e3f322d2ad697015919 ]

The two debug messages in spidev_open() dereference spidev-&gt;spi without
taking the lock and without checking if it's not null. This can lead to
a crash. Drop the messages as they're not needed - the user-space will
get informed about ENOMEM with the syscall return value.

Signed-off-by: Bartosz Golaszewski &lt;bartosz.golaszewski@linaro.org&gt;
Link: https://lore.kernel.org/r/20230106100719.196243-2-brgl@bgdev.pl
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6b35b173dbc1711f8d272e3f322d2ad697015919 ]

The two debug messages in spidev_open() dereference spidev-&gt;spi without
taking the lock and without checking if it's not null. This can lead to
a crash. Drop the messages as they're not needed - the user-space will
get informed about ENOMEM with the syscall return value.

Signed-off-by: Bartosz Golaszewski &lt;bartosz.golaszewski@linaro.org&gt;
Link: https://lore.kernel.org/r/20230106100719.196243-2-brgl@bgdev.pl
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>spi: spi-gpio: Don't set MOSI as an input if not 3WIRE mode</title>
<updated>2023-01-18T10:41:12+00:00</updated>
<author>
<name>Kris Bahnsen</name>
<email>kris@embeddedTS.com</email>
</author>
<published>2022-12-07T23:08:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9e8440a657119eb49e687d83b9c2ead12b997b45'/>
<id>9e8440a657119eb49e687d83b9c2ead12b997b45</id>
<content type='text'>
[ Upstream commit 3a6f994f848a69deb2bf3cd9d130dd0c09730e55 ]

The addition of 3WIRE support would affect MOSI direction even
when still in standard (4 wire) mode. This can lead to MOSI being
at an invalid logic level when a device driver sets an SPI
message with a NULL tx_buf.

spi.h states that if tx_buf is NULL then "zeros will be shifted
out ... " If MOSI is tristated then the data shifted out is subject
to pull resistors, keepers, or in the absence of those, noise.

This issue came to light when using spi-gpio connected to an
ADS7843 touchscreen controller. MOSI pulled high when clocking
MISO data in caused the SPI device to interpret this as a command
which would put the device in an unexpected and non-functional
state.

Fixes: 4b859db2c606 ("spi: spi-gpio: add SPI_3WIRE support")
Fixes: 5132b3d28371 ("spi: gpio: Support 3WIRE high-impedance turn-around")
Signed-off-by: Kris Bahnsen &lt;kris@embeddedTS.com&gt;
Link: https://lore.kernel.org/r/20221207230853.6174-1-kris@embeddedTS.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
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<pre>
[ Upstream commit 3a6f994f848a69deb2bf3cd9d130dd0c09730e55 ]

The addition of 3WIRE support would affect MOSI direction even
when still in standard (4 wire) mode. This can lead to MOSI being
at an invalid logic level when a device driver sets an SPI
message with a NULL tx_buf.

spi.h states that if tx_buf is NULL then "zeros will be shifted
out ... " If MOSI is tristated then the data shifted out is subject
to pull resistors, keepers, or in the absence of those, noise.

This issue came to light when using spi-gpio connected to an
ADS7843 touchscreen controller. MOSI pulled high when clocking
MISO data in caused the SPI device to interpret this as a command
which would put the device in an unexpected and non-functional
state.

Fixes: 4b859db2c606 ("spi: spi-gpio: add SPI_3WIRE support")
Fixes: 5132b3d28371 ("spi: gpio: Support 3WIRE high-impedance turn-around")
Signed-off-by: Kris Bahnsen &lt;kris@embeddedTS.com&gt;
Link: https://lore.kernel.org/r/20221207230853.6174-1-kris@embeddedTS.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
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