linux-kernel - Re: [PATCH 17/34] greybus: arche-ctrl: move device table to its right location

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Date: Tue, 30 Apr 2024 18:41:42 -0500
From: Alex Elder <elder@...e.org>
To: Arnd Bergmann <arnd@...nel.org>, linux-kernel@...r.kernel.org,
 Vaibhav Hiremath <hvaibhav.linux@...il.com>, Johan Hovold
 <johan@...nel.org>, Alex Elder <elder@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Viresh Kumar <viresh.kumar@...aro.org>
Cc: Arnd Bergmann <arnd@...db.de>,
 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
 Luca Ceresoli <luca.ceresoli@...tlin.com>, Rob Herring <robh@...nel.org>,
 greybus-dev@...ts.linaro.org, linux-staging@...ts.linux.dev
Subject: Re: [PATCH 17/34] greybus: arche-ctrl: move device table to its right
 location

On 4/3/24 3:06 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> The arche-ctrl has two platform drivers and three of_device_id tables,
> but one table is only used for the the module loader, while the other
> two seem to be associated with their drivers.
> 
> This leads to a W=1 warning when the driver is built-in:
> 
> drivers/staging/greybus/arche-platform.c:623:34: error: 'arche_combined_id' defined but not used [-Werror=unused-const-variable=]
>    623 | static const struct of_device_id arche_combined_id[] = {
> 
> Drop the extra table and register both tables that are actually
> used as the ones for the module loader instead.

So what I see is that this commit added arche_combined_id[]:
   1e5dd1f8279a8 greybus: arche-platform: merge arche-apb-ctrl and 
arche-platform

That moved the arche_apb_ctrl_device_driver struct and some other
associated bits out of arche-apb-ctrl.c and into arche-platform.c.
It *kept* arche_platform_of_match[] as the of_match_table for
arche_platform_device_driver, but defined arche_combined_id[] and
declared it for modalias to indicate both drivers were implemented
in the single kernel module.

The later commit (the one you references in "Fixes") then moved
the arche_apb_ctrl_device_driver etc. back to arche-apb-ctrl.c.
That commit did *not* use MODULE_DEVICE_TABLE() to declare
arche_apb_ctrl_of_match[] for modalias.  And it simply kept the
(no longer correct) arche_combined_id[] table to be used by the
arche_platform_device_driver.

So your fix:
- Declares for modalias that arche_apb_ctrl_of_match[] is the
   of_match_table for arche_apb_ctrl_device_driver.
- Declares for modalias that arche_platform_of_match[] is the
   of_match_table for arche_platform_device_driver.
- Gets rid of arche_combined_id[], which is no longer used.

In short:  looks good to me.

Reviewed-by: Alex Elder <elder@...aro.org>

> 
> Fixes: 7b62b61c752a ("greybus: arche-ctrl: Don't expose driver internals to arche-platform driver")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>   drivers/staging/greybus/arche-apb-ctrl.c | 1 +
>   drivers/staging/greybus/arche-platform.c | 9 +--------
>   2 files changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/greybus/arche-apb-ctrl.c b/drivers/staging/greybus/arche-apb-ctrl.c
> index 8541995008da..aa6f266b62a1 100644
> --- a/drivers/staging/greybus/arche-apb-ctrl.c
> +++ b/drivers/staging/greybus/arche-apb-ctrl.c
> @@ -466,6 +466,7 @@ static const struct of_device_id arche_apb_ctrl_of_match[] = {
>   	{ .compatible = "usbffff,2", },
>   	{ },
>   };
> +MODULE_DEVICE_TABLE(of, arche_apb_ctrl_of_match);
>   
>   static struct platform_driver arche_apb_ctrl_device_driver = {
>   	.probe		= arche_apb_ctrl_probe,
> diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
> index 891b75327d7f..b33977ccd527 100644
> --- a/drivers/staging/greybus/arche-platform.c
> +++ b/drivers/staging/greybus/arche-platform.c
> @@ -619,14 +619,7 @@ static const struct of_device_id arche_platform_of_match[] = {
>   	{ .compatible = "google,arche-platform", },
>   	{ },
>   };
> -
> -static const struct of_device_id arche_combined_id[] = {
> -	/* Use PID/VID of SVC device */
> -	{ .compatible = "google,arche-platform", },
> -	{ .compatible = "usbffff,2", },
> -	{ },
> -};
> -MODULE_DEVICE_TABLE(of, arche_combined_id);
> +MODULE_DEVICE_TABLE(of, arche_platform_of_match);
>   
>   static struct platform_driver arche_platform_device_driver = {
>   	.probe		= arche_platform_probe,