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

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Message-ID: <20230930145032.GD31829@pendragon.ideasonboard.com>
Date:   Sat, 30 Sep 2023 17:50:32 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Alexandra Diupina <adiupina@...ralinux.ru>
Cc:     Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        dri-devel@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH v2] drm: rcar-du: turn rcar_du_group_get() into void and
 remove its return value check

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@...ralinux.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;
>  }
>  
>  /*

-- 
Regards,

Laurent Pinchart