<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers, branch v6.1.68</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>drm/i915: Skip some timing checks on BXT/GLK DSI transcoders</title>
<updated>2023-12-13T17:39:30+00:00</updated>
<author>
<name>Ville Syrjälä</name>
<email>ville.syrjala@linux.intel.com</email>
</author>
<published>2023-11-27T14:50:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f38b4e99e24cbc45084552fe50273ed847a4f511'/>
<id>f38b4e99e24cbc45084552fe50273ed847a4f511</id>
<content type='text'>
[ Upstream commit 20c2dbff342aec13bf93c2f6c951da198916a455 ]

Apparently some BXT/GLK systems have DSI panels whose timings
don't agree with the normal cpu transcoder hblank&gt;=32 limitation.
This is perhaps fine as there are no specific hblank/etc. limits
listed for the BXT/GLK DSI transcoders.

Move those checks out from the global intel_mode_valid() into
into connector specific .mode_valid() hooks, skipping BXT/GLK
DSI connectors. We'll leave the basic [hv]display/[hv]total
checks in intel_mode_valid() as those seem like sensible upper
limits regardless of the transcoder used.

Cc: stable@vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9720
Fixes: 8f4b1068e7fc ("drm/i915: Check some transcoder timing minimum limits")
Signed-off-by: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20231127145028.4899-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
(cherry picked from commit e0ef2daa8ca8ce4dbc2fd0959e383b753a87fd7d)
Signed-off-by: Jani Nikula &lt;jani.nikula@intel.com&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 20c2dbff342aec13bf93c2f6c951da198916a455 ]

Apparently some BXT/GLK systems have DSI panels whose timings
don't agree with the normal cpu transcoder hblank&gt;=32 limitation.
This is perhaps fine as there are no specific hblank/etc. limits
listed for the BXT/GLK DSI transcoders.

Move those checks out from the global intel_mode_valid() into
into connector specific .mode_valid() hooks, skipping BXT/GLK
DSI connectors. We'll leave the basic [hv]display/[hv]total
checks in intel_mode_valid() as those seem like sensible upper
limits regardless of the transcoder used.

Cc: stable@vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9720
Fixes: 8f4b1068e7fc ("drm/i915: Check some transcoder timing minimum limits")
Signed-off-by: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20231127145028.4899-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
(cherry picked from commit e0ef2daa8ca8ce4dbc2fd0959e383b753a87fd7d)
Signed-off-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/i915/sdvo: stop caching has_hdmi_monitor in struct intel_sdvo</title>
<updated>2023-12-13T17:39:30+00:00</updated>
<author>
<name>Jani Nikula</name>
<email>jani.nikula@intel.com</email>
</author>
<published>2023-05-30T09:08:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d9ef7b05ccd7f4f0d12b7aed2a2e5858809dd4a4'/>
<id>d9ef7b05ccd7f4f0d12b7aed2a2e5858809dd4a4</id>
<content type='text'>
[ Upstream commit f2f9c8cb6421429ef166d6404426693212d0ca07 ]

Use the information stored in display info.

Reviewed-by: Ankit Nautiyal &lt;ankit.k.nautiyal@intel.com&gt;
Signed-off-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/3e9e1dcd554d470bdf474891a431b15e1880f9a0.1685437500.git.jani.nikula@intel.com
Stable-dep-of: 20c2dbff342a ("drm/i915: Skip some timing checks on BXT/GLK DSI transcoders")
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 f2f9c8cb6421429ef166d6404426693212d0ca07 ]

Use the information stored in display info.

Reviewed-by: Ankit Nautiyal &lt;ankit.k.nautiyal@intel.com&gt;
Signed-off-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/3e9e1dcd554d470bdf474891a431b15e1880f9a0.1685437500.git.jani.nikula@intel.com
Stable-dep-of: 20c2dbff342a ("drm/i915: Skip some timing checks on BXT/GLK DSI transcoders")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/i915/lvds: Use REG_BIT() &amp; co.</title>
<updated>2023-12-13T17:39:30+00:00</updated>
<author>
<name>Ville Syrjälä</name>
<email>ville.syrjala@linux.intel.com</email>
</author>
<published>2023-01-30T18:05:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cf70d62ace9070fb8be900fa87cb2e43cbc1fa9f'/>
<id>cf70d62ace9070fb8be900fa87cb2e43cbc1fa9f</id>
<content type='text'>
[ Upstream commit 9dd56e979cb69f5cd904574c852b620777a2f69f ]

Use REG_BIT() &amp; co. for the LVDS port register.

Signed-off-by: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20230130180540.8972-4-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Stable-dep-of: 20c2dbff342a ("drm/i915: Skip some timing checks on BXT/GLK DSI transcoders")
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 9dd56e979cb69f5cd904574c852b620777a2f69f ]

Use REG_BIT() &amp; co. for the LVDS port register.

Signed-off-by: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20230130180540.8972-4-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Stable-dep-of: 20c2dbff342a ("drm/i915: Skip some timing checks on BXT/GLK DSI transcoders")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/i915/display: Drop check for doublescan mode in modevalid</title>
<updated>2023-12-13T17:39:30+00:00</updated>
<author>
<name>Ankit Nautiyal</name>
<email>ankit.k.nautiyal@intel.com</email>
</author>
<published>2022-10-17T14:30:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e6d55cf4939987eb1761cb0cbf47af233123da87'/>
<id>e6d55cf4939987eb1761cb0cbf47af233123da87</id>
<content type='text'>
[ Upstream commit 9d04eb20bc71a383b4d4e383b0b7fac8d38a2e34 ]

Since the DP/HDMI connector do not set connector-&gt;doublescan_allowed,
the doublescan modes will get automatically filtered during
drm_helper_probe_single_connector_modes().

Therefore check for double scan modes is not required and is dropped
from modevalid functions for both DP and HDMI.

Signed-off-by: Ankit Nautiyal &lt;ankit.k.nautiyal@intel.com&gt;
Reviewed-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Signed-off-by: Uma Shankar &lt;uma.shankar@intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20221017143038.1748319-2-ankit.k.nautiyal@intel.com
Stable-dep-of: 20c2dbff342a ("drm/i915: Skip some timing checks on BXT/GLK DSI transcoders")
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 9d04eb20bc71a383b4d4e383b0b7fac8d38a2e34 ]

Since the DP/HDMI connector do not set connector-&gt;doublescan_allowed,
the doublescan modes will get automatically filtered during
drm_helper_probe_single_connector_modes().

Therefore check for double scan modes is not required and is dropped
from modevalid functions for both DP and HDMI.

Signed-off-by: Ankit Nautiyal &lt;ankit.k.nautiyal@intel.com&gt;
Reviewed-by: Jani Nikula &lt;jani.nikula@intel.com&gt;
Signed-off-by: Uma Shankar &lt;uma.shankar@intel.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20221017143038.1748319-2-ankit.k.nautiyal@intel.com
Stable-dep-of: 20c2dbff342a ("drm/i915: Skip some timing checks on BXT/GLK DSI transcoders")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>USB: gadget: core: adjust uevent timing on gadget unbind</title>
<updated>2023-12-13T17:39:28+00:00</updated>
<author>
<name>Roy Luo</name>
<email>royluo@google.com</email>
</author>
<published>2023-11-28T22:17:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=69540c108d72299c418afce151e2e99e82820987'/>
<id>69540c108d72299c418afce151e2e99e82820987</id>
<content type='text'>
commit 73ea73affe8622bdf292de898da869d441da6a9d upstream.

The KOBJ_CHANGE uevent is sent before gadget unbind is actually
executed, resulting in inaccurate uevent emitted at incorrect timing
(the uevent would have USB_UDC_DRIVER variable set while it would
soon be removed).
Move the KOBJ_CHANGE uevent to the end of the unbind function so that
uevent is sent only after the change has been made.

Fixes: 2ccea03a8f7e ("usb: gadget: introduce UDC Class")
Cc: stable@vger.kernel.org
Signed-off-by: Roy Luo &lt;royluo@google.com&gt;
Link: https://lore.kernel.org/r/20231128221756.2591158-1-royluo@google.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 73ea73affe8622bdf292de898da869d441da6a9d upstream.

The KOBJ_CHANGE uevent is sent before gadget unbind is actually
executed, resulting in inaccurate uevent emitted at incorrect timing
(the uevent would have USB_UDC_DRIVER variable set while it would
soon be removed).
Move the KOBJ_CHANGE uevent to the end of the unbind function so that
uevent is sent only after the change has been made.

Fixes: 2ccea03a8f7e ("usb: gadget: introduce UDC Class")
Cc: stable@vger.kernel.org
Signed-off-by: Roy Luo &lt;royluo@google.com&gt;
Link: https://lore.kernel.org/r/20231128221756.2591158-1-royluo@google.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>devcoredump: Send uevent once devcd is ready</title>
<updated>2023-12-13T17:39:28+00:00</updated>
<author>
<name>Mukesh Ojha</name>
<email>quic_mojha@quicinc.com</email>
</author>
<published>2023-11-17T14:49:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0553d52908797aba12fd51065abf01e769ca9707'/>
<id>0553d52908797aba12fd51065abf01e769ca9707</id>
<content type='text'>
commit af54d778a03853801d681c98c0c2a6c316ef9ca7 upstream.

dev_coredumpm() creates a devcoredump device and adds it
to the core kernel framework which eventually end up
sending uevent to the user space and later creates a
symbolic link to the failed device. An application
running in userspace may be interested in this symbolic
link to get the name of the failed device.

In a issue scenario, once uevent sent to the user space
it start reading '/sys/class/devcoredump/devcdX/failing_device'
to get the actual name of the device which might not been
created and it is in its path of creation.

To fix this, suppress sending uevent till the failing device
symbolic link gets created and send uevent once symbolic
link is created successfully.

Fixes: 833c95456a70 ("device coredump: add new device coredump class")
Signed-off-by: Mukesh Ojha &lt;quic_mojha@quicinc.com&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1700232572-25823-1-git-send-email-quic_mojha@quicinc.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit af54d778a03853801d681c98c0c2a6c316ef9ca7 upstream.

dev_coredumpm() creates a devcoredump device and adds it
to the core kernel framework which eventually end up
sending uevent to the user space and later creates a
symbolic link to the failed device. An application
running in userspace may be interested in this symbolic
link to get the name of the failed device.

In a issue scenario, once uevent sent to the user space
it start reading '/sys/class/devcoredump/devcdX/failing_device'
to get the actual name of the device which might not been
created and it is in its path of creation.

To fix this, suppress sending uevent till the failing device
symbolic link gets created and send uevent once symbolic
link is created successfully.

Fixes: 833c95456a70 ("device coredump: add new device coredump class")
Signed-off-by: Mukesh Ojha &lt;quic_mojha@quicinc.com&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1700232572-25823-1-git-send-email-quic_mojha@quicinc.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: 8250_omap: Add earlycon support for the AM654 UART controller</title>
<updated>2023-12-13T17:39:28+00:00</updated>
<author>
<name>Ronald Wahl</name>
<email>ronald.wahl@raritan.com</email>
</author>
<published>2023-10-31T13:12:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=74799b43d856a40d7cc280e73ab5b70df5715bc8'/>
<id>74799b43d856a40d7cc280e73ab5b70df5715bc8</id>
<content type='text'>
commit 8e42c301ce64e0dcca547626eb486877d502d336 upstream.

Currently there is no support for earlycon on the AM654 UART
controller. This commit adds it.

Signed-off-by: Ronald Wahl &lt;ronald.wahl@raritan.com&gt;
Reviewed-by: Vignesh Raghavendra &lt;vigneshr@ti.com&gt;
Link: https://lore.kernel.org/r/20231031131242.15516-1-rwahl@gmx.de
Cc: stable &lt;stable@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>
commit 8e42c301ce64e0dcca547626eb486877d502d336 upstream.

Currently there is no support for earlycon on the AM654 UART
controller. This commit adds it.

Signed-off-by: Ronald Wahl &lt;ronald.wahl@raritan.com&gt;
Reviewed-by: Vignesh Raghavendra &lt;vigneshr@ti.com&gt;
Link: https://lore.kernel.org/r/20231031131242.15516-1-rwahl@gmx.de
Cc: stable &lt;stable@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: 8250: 8250_omap: Do not start RX DMA on THRI interrupt</title>
<updated>2023-12-13T17:39:28+00:00</updated>
<author>
<name>Ronald Wahl</name>
<email>ronald.wahl@raritan.com</email>
</author>
<published>2023-11-01T17:14:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d59dafa9eb12e0a558ea7d7d561ddcd0c9c2a29e'/>
<id>d59dafa9eb12e0a558ea7d7d561ddcd0c9c2a29e</id>
<content type='text'>
commit c6bb057418876cdfdd29a6f7b8cef54539ee8811 upstream.

Starting RX DMA on THRI interrupt is too early because TX may not have
finished yet.

This change is inspired by commit 90b8596ac460 ("serial: 8250: Prevent
starting up DMA Rx on THRI interrupt") and fixes DMA issues I had with
an AM62 SoC that is using the 8250 OMAP variant.

Cc: stable@vger.kernel.org
Fixes: c26389f998a8 ("serial: 8250: 8250_omap: Add DMA support for UARTs on K3 SoCs")
Signed-off-by: Ronald Wahl &lt;ronald.wahl@raritan.com&gt;
Reviewed-by: Vignesh Raghavendra &lt;vigneshr@ti.com&gt;
Link: https://lore.kernel.org/r/20231101171431.16495-1-rwahl@gmx.de
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c6bb057418876cdfdd29a6f7b8cef54539ee8811 upstream.

Starting RX DMA on THRI interrupt is too early because TX may not have
finished yet.

This change is inspired by commit 90b8596ac460 ("serial: 8250: Prevent
starting up DMA Rx on THRI interrupt") and fixes DMA issues I had with
an AM62 SoC that is using the 8250 OMAP variant.

Cc: stable@vger.kernel.org
Fixes: c26389f998a8 ("serial: 8250: 8250_omap: Add DMA support for UARTs on K3 SoCs")
Signed-off-by: Ronald Wahl &lt;ronald.wahl@raritan.com&gt;
Reviewed-by: Vignesh Raghavendra &lt;vigneshr@ti.com&gt;
Link: https://lore.kernel.org/r/20231101171431.16495-1-rwahl@gmx.de
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: 8250: 8250_omap: Clear UART_HAS_RHR_IT_DIS bit</title>
<updated>2023-12-13T17:39:27+00:00</updated>
<author>
<name>Ronald Wahl</name>
<email>ronald.wahl@raritan.com</email>
</author>
<published>2023-10-31T11:09:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=638a6cbacefd13700c9315c4264d5f928c6204b1'/>
<id>638a6cbacefd13700c9315c4264d5f928c6204b1</id>
<content type='text'>
commit 8973ab7a2441b286218f4a5c4c33680e2f139996 upstream.

This fixes commit 439c7183e5b9 ("serial: 8250: 8250_omap: Disable RX
interrupt after DMA enable") which unfortunately set the
UART_HAS_RHR_IT_DIS bit in the UART_OMAP_IER2 register and never
cleared it.

Cc: stable@vger.kernel.org
Fixes: 439c7183e5b9 ("serial: 8250: 8250_omap: Disable RX interrupt after DMA enable")
Signed-off-by: Ronald Wahl &lt;ronald.wahl@raritan.com&gt;
Reviewed-by: Vignesh Raghavendra &lt;vigneshr@ti.com&gt;
Link: https://lore.kernel.org/r/20231031110909.11695-1-rwahl@gmx.de
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 8973ab7a2441b286218f4a5c4c33680e2f139996 upstream.

This fixes commit 439c7183e5b9 ("serial: 8250: 8250_omap: Disable RX
interrupt after DMA enable") which unfortunately set the
UART_HAS_RHR_IT_DIS bit in the UART_OMAP_IER2 register and never
cleared it.

Cc: stable@vger.kernel.org
Fixes: 439c7183e5b9 ("serial: 8250: 8250_omap: Disable RX interrupt after DMA enable")
Signed-off-by: Ronald Wahl &lt;ronald.wahl@raritan.com&gt;
Reviewed-by: Vignesh Raghavendra &lt;vigneshr@ti.com&gt;
Link: https://lore.kernel.org/r/20231031110909.11695-1-rwahl@gmx.de
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>serial: sc16is7xx: address RX timeout interrupt errata</title>
<updated>2023-12-13T17:39:27+00:00</updated>
<author>
<name>Daniel Mack</name>
<email>daniel@zonque.org</email>
</author>
<published>2023-11-23T07:28:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f434703fb893ddffcdbc1eec7646ce321e1190a8'/>
<id>f434703fb893ddffcdbc1eec7646ce321e1190a8</id>
<content type='text'>
commit 08ce9a1b72e38cf44c300a44ac5858533eb3c860 upstream.

This device has a silicon bug that makes it report a timeout interrupt
but no data in the FIFO.

The datasheet states the following in the errata section 18.1.4:

  "If the host reads the receive FIFO at the same time as a
  time-out interrupt condition happens, the host might read 0xCC
  (time-out) in the Interrupt Indication Register (IIR), but bit 0
  of the Line Status Register (LSR) is not set (means there is no
  data in the receive FIFO)."

The errata description seems to indicate it concerns only polled mode of
operation when reading bit 0 of the LSR register. However, tests have
shown and NXP has confirmed that the RXLVL register also yields 0 when
the bug is triggered, and hence the IRQ driven implementation in this
driver is equally affected.

This bug has hit us on production units and when it does, sc16is7xx_irq()
would spin forever because sc16is7xx_port_irq() keeps seeing an
interrupt in the IIR register that is not cleared because the driver
does not call into sc16is7xx_handle_rx() unless the RXLVL register
reports at least one byte in the FIFO.

Fix this by always reading one byte from the FIFO when this condition
is detected in order to clear the interrupt. This approach was
confirmed to be correct by NXP through their support channels.

Tested by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;

Signed-off-by: Daniel Mack &lt;daniel@zonque.org&gt;
Co-Developed-by: Maxim Popov &lt;maxim.snafu@gmail.com&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20231123072818.1394539-1-daniel@zonque.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<pre>
commit 08ce9a1b72e38cf44c300a44ac5858533eb3c860 upstream.

This device has a silicon bug that makes it report a timeout interrupt
but no data in the FIFO.

The datasheet states the following in the errata section 18.1.4:

  "If the host reads the receive FIFO at the same time as a
  time-out interrupt condition happens, the host might read 0xCC
  (time-out) in the Interrupt Indication Register (IIR), but bit 0
  of the Line Status Register (LSR) is not set (means there is no
  data in the receive FIFO)."

The errata description seems to indicate it concerns only polled mode of
operation when reading bit 0 of the LSR register. However, tests have
shown and NXP has confirmed that the RXLVL register also yields 0 when
the bug is triggered, and hence the IRQ driven implementation in this
driver is equally affected.

This bug has hit us on production units and when it does, sc16is7xx_irq()
would spin forever because sc16is7xx_port_irq() keeps seeing an
interrupt in the IIR register that is not cleared because the driver
does not call into sc16is7xx_handle_rx() unless the RXLVL register
reports at least one byte in the FIFO.

Fix this by always reading one byte from the FIFO when this condition
is detected in order to clear the interrupt. This approach was
confirmed to be correct by NXP through their support channels.

Tested by: Hugo Villeneuve &lt;hvilleneuve@dimonoff.com&gt;

Signed-off-by: Daniel Mack &lt;daniel@zonque.org&gt;
Co-Developed-by: Maxim Popov &lt;maxim.snafu@gmail.com&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20231123072818.1394539-1-daniel@zonque.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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