[PATCH v3] i2c: acpi: Do not create i2c-clients for LNXVIDEO ACPI devices

[PATCH v3] i2c: acpi: Do not create i2c-clients for LNXVIDEO ACPI devices

[Hans de Goede]

ACPI video devices get tagged by the kernel with the custom LNXVIDEO
HID so that normal pnp-id matching can be used and are handled by the
acpi-video driver.

Sometimes the ACPI nodes describing these contain a SERIAL_TYPE_I2C ACPI
resource. Before this commit the presence of this resource would cause the
i2c-core to create a /sys/bus/i2c/devices/i2c-LNXVIDEO:00 device for this
with a modalias of: "i2c:LNXVIDEO:00".

There is no i2c driver for this custom HID, the acpi-video driver binds
directly to the ACPI device /sys/bus/acpi/devices/LNXVIDEO\:00 which has
a modalias of "acpi:LNXVIDEO:" .

Not only is the creation of an i2c-client for this undesirable, it is
actually causing problems. This weird pseudo-resource claims an i2c
speed of 100KHz and typically points to the i2c bus which is used by the
touchscreen controller. Some touchscreen controllers only work properly at
400KHz, at 100KHz they cause errors like these:

i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
silead_ts i2c-MSSL1680:00: Registers clear error -11

This commit makes the i2c-core ignore LNXVIDEO compatible ACPI devices
which has 2 positive results:

1) The bogus i2c-client for these is no longer created.
2) i2c_acpi_lookup_speed now ignores the 100KHz speed from the pseudo
i2c-resouce and properly returns 400KHz as speed for the touchscreen
i2c bus, fixing the touchscreen not working on various devies.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
-Rebase on top of linux-i2c/for-next

Changes in v3:
-Rename the acpi_device_id-s array to ignored_device_ids
-Move the acpi_device_id-s array outside of i2c_acpi_do_lookup
---
 drivers/i2c/i2c-core-acpi.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index 052005579ed6..4842ec3a5451 100644
--- a/drivers/i2c/i2c-core-acpi.c
+++ b/drivers/i2c/i2c-core-acpi.c
@@ -76,6 +76,15 @@ static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data)
 	return 1;
 }
 
+static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
+	/*
+	 * ACPI video acpi_devices, which are handled by the acpi-video driver
+	 * sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore these.
+	 */
+	{ ACPI_VIDEO_HID, 0 },
+	{}
+};
+
 static int i2c_acpi_do_lookup(struct acpi_device *adev,
 			      struct i2c_acpi_lookup *lookup)
 {
@@ -87,6 +96,9 @@ static int i2c_acpi_do_lookup(struct acpi_device *adev,
 	    acpi_device_enumerated(adev))
 		return -EINVAL;
 
+	if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids) == 0)
+		return -ENODEV;
+
 	memset(info, 0, sizeof(*info));
 	lookup->device_handle = acpi_device_handle(adev);
 
-- 
2.13.0

Re: [PATCH v3] i2c: acpi: Do not create i2c-clients for LNXVIDEO ACPI devices

[Andy Shevchenko]

On Tue, 2017-07-04 at 15:04 +0200, Hans de Goede wrote:
> ACPI video devices get tagged by the kernel with the custom LNXVIDEO
> HID so that normal pnp-id matching can be used and are handled by the
> acpi-video driver.
> 
> Sometimes the ACPI nodes describing these contain a SERIAL_TYPE_I2C
> ACPI
> resource. Before this commit the presence of this resource would cause
> the
> i2c-core to create a /sys/bus/i2c/devices/i2c-LNXVIDEO:00 device for
> this
> with a modalias of: "i2c:LNXVIDEO:00".
> 
> There is no i2c driver for this custom HID, the acpi-video driver
> binds
> directly to the ACPI device /sys/bus/acpi/devices/LNXVIDEO\:00 which
> has
> a modalias of "acpi:LNXVIDEO:" .
> 
> Not only is the creation of an i2c-client for this undesirable, it is
> actually causing problems. This weird pseudo-resource claims an i2c
> speed of 100KHz and typically points to the i2c bus which is used by
> the
> touchscreen controller. Some touchscreen controllers only work
> properly at
> 400KHz, at 100KHz they cause errors like these:
> 
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> silead_ts i2c-MSSL1680:00: Registers clear error -11
> 
> This commit makes the i2c-core ignore LNXVIDEO compatible ACPI devices
> which has 2 positive results:
> 
> 1) The bogus i2c-client for these is no longer created.
> 2) i2c_acpi_lookup_speed now ignores the 100KHz speed from the pseudo
> i2c-resouce and properly returns 400KHz as speed for the touchscreen
> i2c bus, fixing the touchscreen not working on various devies.
> 

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>


> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> Changes in v2:
> -Rebase on top of linux-i2c/for-next
> 
> Changes in v3:
> -Rename the acpi_device_id-s array to ignored_device_ids
> -Move the acpi_device_id-s array outside of i2c_acpi_do_lookup
> ---
>  drivers/i2c/i2c-core-acpi.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> index 052005579ed6..4842ec3a5451 100644
> --- a/drivers/i2c/i2c-core-acpi.c
> +++ b/drivers/i2c/i2c-core-acpi.c
> @@ -76,6 +76,15 @@ static int i2c_acpi_fill_info(struct acpi_resource
> *ares, void *data)
>  	return 1;
>  }
>  
> +static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
> +	/*
> +	 * ACPI video acpi_devices, which are handled by the acpi-
> video driver
> +	 * sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore
> these.
> +	 */
> +	{ ACPI_VIDEO_HID, 0 },
> +	{}
> +};
> +
>  static int i2c_acpi_do_lookup(struct acpi_device *adev,
>  			      struct i2c_acpi_lookup *lookup)
>  {
> @@ -87,6 +96,9 @@ static int i2c_acpi_do_lookup(struct acpi_device
> *adev,
>  	    acpi_device_enumerated(adev))
>  		return -EINVAL;
>  
> +	if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids)
> == 0)
> +		return -ENODEV;
> +
>  	memset(info, 0, sizeof(*info));
>  	lookup->device_handle = acpi_device_handle(adev);
>  

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v3] i2c: acpi: Do not create i2c-clients for LNXVIDEO ACPI devices

[Wolfram Sang]

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On Tue, Jul 04, 2017 at 03:04:48PM +0200, Hans de Goede wrote:
> ACPI video devices get tagged by the kernel with the custom LNXVIDEO
> HID so that normal pnp-id matching can be used and are handled by the
> acpi-video driver.
> 
> Sometimes the ACPI nodes describing these contain a SERIAL_TYPE_I2C ACPI
> resource. Before this commit the presence of this resource would cause the
> i2c-core to create a /sys/bus/i2c/devices/i2c-LNXVIDEO:00 device for this
> with a modalias of: "i2c:LNXVIDEO:00".
> 
> There is no i2c driver for this custom HID, the acpi-video driver binds
> directly to the ACPI device /sys/bus/acpi/devices/LNXVIDEO\:00 which has
> a modalias of "acpi:LNXVIDEO:" .
> 
> Not only is the creation of an i2c-client for this undesirable, it is
> actually causing problems. This weird pseudo-resource claims an i2c
> speed of 100KHz and typically points to the i2c bus which is used by the
> touchscreen controller. Some touchscreen controllers only work properly at
> 400KHz, at 100KHz they cause errors like these:
> 
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> i2c_designware 80860F41:03: i2c_dw_handle_tx_abort: lost arbitration
> silead_ts i2c-MSSL1680:00: Registers clear error -11
> 
> This commit makes the i2c-core ignore LNXVIDEO compatible ACPI devices
> which has 2 positive results:
> 
> 1) The bogus i2c-client for these is no longer created.
> 2) i2c_acpi_lookup_speed now ignores the 100KHz speed from the pseudo
> i2c-resouce and properly returns 400KHz as speed for the touchscreen
> i2c bus, fixing the touchscreen not working on various devies.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Looks like a bugfix, so I'll include it in this merge window.

Applied to for-next, thanks!


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