[v2] drm: rcar-du: turn rcar_du_group_get() into void and remove its return value check

  rcar_du_group_get() never returns a negative
error code (always returns 0), so change the comment
about returned value, turn function into void (return
code of rcar_du_group_get has been redundant for a
long time, so perhaps it's just not required) and
remove redundant error path handling in rcar_du_crtc_get()

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 0bb63534fdf3 ("drm: rcar-du: Perform the initial CRTC setup from rcar_du_crtc_get()")
Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
---
v2: rcar_du_group_get() is turned into void and its return 
value check is removed in rcar_du_crtc_get()
 drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c  | 6 +-----
 drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c | 5 +----
 2 files changed, 2 insertions(+), 9 deletions(-)
  

Hi Alexandra,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.6-rc3 next-20230929]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Alexandra-Diupina/drm-rcar-du-turn-rcar_du_group_get-into-void-and-remove-its-return-value-check/20230927-184651
base:   linus/master
patch link:    https://lore.kernel.org/r/20230927104438.30628-1-adiupina%40astralinux.ru
patch subject: [PATCH v2] drm: rcar-du: turn rcar_du_group_get() into void and remove its return value check
config: arm-allyesconfig (https://download.01.org/0day-ci/archive/20230930/202309301402.uR7IRQVj-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230930/202309301402.uR7IRQVj-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309301402.uR7IRQVj-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c:203:6: error: conflicting types for 'rcar_du_group_get'; have 'void(struct rcar_du_group *)'
     203 | void rcar_du_group_get(struct rcar_du_group *rgrp)
         |      ^~~~~~~~~~~~~~~~~
   In file included from drivers/gpu/drm/renesas/rcar-du/rcar_du_drv.h:20,
                    from drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c:29:
   drivers/gpu/drm/renesas/rcar-du/rcar_du_group.h:57:5: note: previous declaration of 'rcar_du_group_get' with type 'int(struct rcar_du_group *)'
      57 | int rcar_du_group_get(struct rcar_du_group *rgrp);
         |     ^~~~~~~~~~~~~~~~~


vim +203 drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c

   194	
   195	/*
   196	 * rcar_du_group_get - Acquire a reference to the DU channels group
   197	 *
   198	 * Acquiring the first reference setups core registers. A reference must be held
   199	 * before accessing any hardware registers.
   200	 *
   201	 * This function must be called with the DRM mode_config lock held.
   202	 */
 > 203	void rcar_du_group_get(struct rcar_du_group *rgrp)
   204	{
   205		if (rgrp->use_count)
   206			goto done;
   207	
   208		rcar_du_group_setup(rgrp);
   209	
   210	done:
   211		rgrp->use_count++;
   212	}
   213
  

Hi Alexandra,

On Wed, Sep 27, 2023 at 01:44:38PM +0300, Alexandra Diupina wrote:
> rcar_du_group_get() never returns a negative
> error code (always returns 0), so change the comment
> about returned value, turn function into void (return
> code of rcar_du_group_get has been redundant for a
> long time, so perhaps it's just not required) and
> remove redundant error path handling in rcar_du_crtc_get()
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.

Using tools to find issues is fine in principle, but not even
compile-testing the resulting patch before submitting it is not.

> Fixes: 0bb63534fdf3 ("drm: rcar-du: Perform the initial CRTC setup from rcar_du_crtc_get()")
> Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
> ---
> v2: rcar_du_group_get() is turned into void and its return 
> value check is removed in rcar_du_crtc_get()
>  drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c  | 6 +-----
>  drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c | 5 +----
>  2 files changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c
> index 7e175dbfd892..2be7c6e64d72 100644
> --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c
> @@ -565,17 +565,13 @@ static int rcar_du_crtc_get(struct rcar_du_crtc *rcrtc)
>  	if (ret < 0)
>  		goto error_clock;
>  
> -	ret = rcar_du_group_get(rcrtc->group);
> -	if (ret < 0)
> -		goto error_group;
> +	rcar_du_group_get(rcrtc->group);
>  
>  	rcar_du_crtc_setup(rcrtc);
>  	rcrtc->initialized = true;
>  
>  	return 0;
>  
> -error_group:
> -	clk_disable_unprepare(rcrtc->extclock);
>  error_clock:
>  	clk_disable_unprepare(rcrtc->clock);
>  	return ret;
> diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c
> index 2ccd2581f544..7113025dabff 100644
> --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c
> +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_group.c
> @@ -199,10 +199,8 @@ static void rcar_du_group_setup(struct rcar_du_group *rgrp)
>   * before accessing any hardware registers.
>   *
>   * This function must be called with the DRM mode_config lock held.
> - *
> - * Return 0 in case of success or a negative error code otherwise.
>   */
> -int rcar_du_group_get(struct rcar_du_group *rgrp)
> +void rcar_du_group_get(struct rcar_du_group *rgrp)
>  {
>  	if (rgrp->use_count)
>  		goto done;
> @@ -211,7 +209,6 @@ int rcar_du_group_get(struct rcar_du_group *rgrp)
>  
>  done:
>  	rgrp->use_count++;
> -	return 0;
>  }
>  
>  /*
  

Hi Laurent,

I'm sorry, my mistake. Thank you for your comment, I will be more 
careful in the future

30.09.2023 17:50, Laurent Pinchart пишет:
> Using tools to find issues is fine in principle, but not even
> compile-testing the resulting patch before submitting it is not.



Alexandra