[03/10,v2] Input: stmpe-ts - use module alias instead of device table

Commit Message

Arnd Bergmann April 9, 2025, 12:22 p.m. UTC

From: Arnd Bergmann <[e-mail]>

When compile tested with W=1 on x86_64 with driver as built-in:

  stmpe-ts.c:371:34: error: unused variable 'stmpe_ts_ids' [-Werror,-Wunused-const-variable]

Ideally this would be referenced from the platform_driver, but since
the compatible string is already matched by the mfd driver for its
parent device, that would break probing.

In this case, the of_device_id table just serves as a module alias
for loading the driver, while the device itself is probed using
the platform device name.

Remove the table and instead use a module alias that reflects how
the driver is actually probed.

Link: https://lore.kernel.org/lkml/[e-mail]/
Link: https://lore.kernel.org/lkml/[e-mail]/
Cc: Uwe Kleine-König" <[e-mail]>
Cc: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
---
v2: use a different approach, hopefully this makes more sense.
---
 drivers/input/touchscreen/stmpe-ts.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

Comments

Andy Shevchenko April 9, 2025, 3:33 p.m. UTC | #1

On Wed, Apr 09, 2025 at 02:22:55PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <[e-mail]>
> 
> When compile tested with W=1 on x86_64 with driver as built-in:
> 
>   stmpe-ts.c:371:34: error: unused variable 'stmpe_ts_ids' [-Werror,-Wunused-const-variable]
> 
> Ideally this would be referenced from the platform_driver, but since
> the compatible string is already matched by the mfd driver for its
> parent device, that would break probing.
> 
> In this case, the of_device_id table just serves as a module alias
> for loading the driver, while the device itself is probed using
> the platform device name.
> 
> Remove the table and instead use a module alias that reflects how
> the driver is actually probed.

...

> +MODULE_ALIAS("platform:stmpe-ts");

Isn't the preferable way to have platform device ID table instead?
Krzysztof?

Krzysztof Kozlowski April 9, 2025, 3:49 p.m. UTC | #2

On 09/04/2025 17:33, Andy Shevchenko wrote:
> On Wed, Apr 09, 2025 at 02:22:55PM +0200, Arnd Bergmann wrote:
>> From: Arnd Bergmann <[e-mail]>
>>
>> When compile tested with W=1 on x86_64 with driver as built-in:
>>
>>   stmpe-ts.c:371:34: error: unused variable 'stmpe_ts_ids' [-Werror,-Wunused-const-variable]
>>
>> Ideally this would be referenced from the platform_driver, but since
>> the compatible string is already matched by the mfd driver for its
>> parent device, that would break probing.
>>
>> In this case, the of_device_id table just serves as a module alias
>> for loading the driver, while the device itself is probed using
>> the platform device name.
>>
>> Remove the table and instead use a module alias that reflects how
>> the driver is actually probed.
> 
> ...
> 
>> +MODULE_ALIAS("platform:stmpe-ts");
> 
> Isn't the preferable way to have platform device ID table instead?
> Krzysztof?

There is no ID table currently and I (usually) object for having both:
ID tables and aliases. In this case it is just simpler to have alias
than entire table and MODULE_DEVICE_TABLE(). Also it is unlikely it will
grow into many aliases. If it tries, then I will object.


Reviewed-by: Krzysztof Kozlowski <[e-mail]>

Best regards,
Krzysztof

Patch

diff --git a/drivers/input/touchscreen/stmpe-ts.c b/drivers/input/touchscreen/stmpe-ts.c
index a94a1997f96b..af0fb38bcfdc 100644
--- a/drivers/input/touchscreen/stmpe-ts.c
+++ b/drivers/input/touchscreen/stmpe-ts.c
@@ -366,12 +366,7 @@  static struct platform_driver stmpe_ts_driver = {
 };
 module_platform_driver(stmpe_ts_driver);
 
-static const struct of_device_id stmpe_ts_ids[] = {
-	{ .compatible = "st,stmpe-ts", },
-	{ },
-};
-MODULE_DEVICE_TABLE(of, stmpe_ts_ids);
-
+MODULE_ALIAS("platform:stmpe-ts");
 MODULE_AUTHOR("Luotao Fu <[e-mail]>");
 MODULE_DESCRIPTION("STMPEXXX touchscreen driver");
 MODULE_LICENSE("GPL");