linux-kernel - Re: [PATCH v3 2/6] drm: lcdif: Drop unnecessary NULL pointer check on lcdif->bridge

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Message-ID: <10229432.nUPlyArG6x@steina-w>
Date:   Tue, 14 Feb 2023 14:42:54 +0100
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Liu Ying <victor.liu@....com>
Cc:     marex@...x.de, stefan@...er.ch, airlied@...il.com, daniel@...ll.ch,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, linux-imx@....com,
        krzysztof.kozlowski@...aro.org, LW@...o-electronics.de
Subject: Re: [PATCH v3 2/6] drm: lcdif: Drop unnecessary NULL pointer check on lcdif->bridge

Hi Liu,

thanks for the update.

Am Montag, 13. Februar 2023, 09:56:08 CET schrieb Liu Ying:
> A valid bridge is already found in lcdif_attach_bridge() and set
> to lcdif->bridge, so lcdif->bridge cannot be a NULL pointer. Drop
> the unnecessary NULL pointer check in KMS stage.
> 
> Signed-off-by: Liu Ying <victor.liu@....com>
> ---
> v2->v3:
> * No change.
> 
> v1->v2:
> * Split from patch 2/2 in v1. (Marek, Alexander)
> 
>  drivers/gpu/drm/mxsfb/lcdif_kms.c | 33 +++++++++++--------------------
>  1 file changed, 12 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> b/drivers/gpu/drm/mxsfb/lcdif_kms.c index 262bc43b1079..e54200a9fcb9 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> @@ -394,7 +394,7 @@ static void lcdif_crtc_mode_set_nofb(struct
> lcdif_drm_private *lcdif, struct drm_display_mode *m =
> &lcdif->crtc.state->adjusted_mode;
>  	u32 bus_flags = 0;
> 
> -	if (lcdif->bridge && lcdif->bridge->timings)
> +	if (lcdif->bridge->timings)
>  		bus_flags = lcdif->bridge->timings->input_bus_flags;
>  	else if (bridge_state)
>  		bus_flags = bridge_state->input_bus_cfg.flags;
> @@ -463,30 +463,21 @@ static void lcdif_crtc_atomic_enable(struct drm_crtc
> *crtc, struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
>  	struct drm_bridge_state *bridge_state = NULL;
>  	struct drm_device *drm = lcdif->drm;
> -	u32 bus_format = 0;
> +	u32 bus_format;
>  	dma_addr_t paddr;
> 
> -	/* If there is a bridge attached to the LCDIF, use its bus format */
> -	if (lcdif->bridge) {
> -		bridge_state =
> -			drm_atomic_get_new_bridge_state(state,
> -							lcdif-
>bridge);
> -		if (!bridge_state)
> -			bus_format = MEDIA_BUS_FMT_FIXED;
> -		else
> -			bus_format = bridge_state->input_bus_cfg.format;
> -
> -		if (bus_format == MEDIA_BUS_FMT_FIXED) {
> -			dev_warn_once(drm->dev,
> -				      "Bridge does not provide bus 
format, assuming
> MEDIA_BUS_FMT_RGB888_1X24.\n" -				      
"Please fix bridge driver by
> handling atomic_get_input_bus_fmts.\n"); -			
bus_format =
> MEDIA_BUS_FMT_RGB888_1X24;
> -		}
> -	}
> +	bridge_state = drm_atomic_get_new_bridge_state(state, lcdif-
>bridge);
> +	if (!bridge_state)
> +		bus_format = MEDIA_BUS_FMT_FIXED;
> +	else
> +		bus_format = bridge_state->input_bus_cfg.format;
> 
> -	/* If all else fails, default to RGB888_1X24 */
> -	if (!bus_format)
> +	if (bus_format == MEDIA_BUS_FMT_FIXED) {
> +		dev_warn_once(drm->dev,
> +			      "Bridge does not provide bus format, 
assuming
> MEDIA_BUS_FMT_RGB888_1X24.\n" +			      "Please fix 
bridge driver by
> handling atomic_get_input_bus_fmts.\n"); bus_format =
> MEDIA_BUS_FMT_RGB888_1X24;
> +	}
> 
>  	clk_set_rate(lcdif->clk, m->crtc_clock * 1000);


LGTM.
Reviewed-by: Alexander Stein <alexander.stein@...tq-group.com>

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