[PATCH 07/12] drm/panic: Retry in dispatch function if panic output fails

[Jocelyn Falempe]

On 18/08/2026 14:28, Thomas Zimmermann wrote:
> On failed output of QR codes and kmsg buffers, fall back to a user
> message. QR-code output already did this internally, but now formally
> support it in drm_panic_dispatch(). Streamlines the existing logic.
> 
> Also pass module parameter drm_panic_type as a parameter to
> drm_panic_dispatch(). This simpifies the implementation. It will later
> allow for moving the function into a helper library.

Thanks, it looks good to me.

Reviewed-by: Jocelyn Falempe <jfalempe at redhat.com>
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> ---
>   drivers/gpu/drm/drm_panic.c | 24 ++++++++++++------------
>   1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
> index 12c39217cbcb..0960750bfce2 100644
> --- a/drivers/gpu/drm/drm_panic.c
> +++ b/drivers/gpu/drm/drm_panic.c
> @@ -746,9 +746,9 @@ static int drm_panic_get_qr_code(u8 **qr_image, unsigned int qr_version)
>   /*
>    * Draw the panic message at the center of the screen, with a QR Code
>    */
> -static int _draw_panic_screen_qr_code(struct drm_scanout_buffer *sb,
> -				      u32 fg_color, u32 bg_color,
> -				      unsigned int qr_version)
> +static int draw_panic_screen_qr_code(struct drm_scanout_buffer *sb,
> +				     u32 fg_color, u32 bg_color,
> +				     unsigned int qr_version)
>   {
>   	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
>   	struct drm_rect r_screen, r_logo, r_msg, r_qr, r_qr_canvas;
> @@ -816,15 +816,6 @@ static int _draw_panic_screen_qr_code(struct drm_scanout_buffer *sb,
>   	drm_panic_blit(sb, &r_qr, qr_image, qr_pitch, scale, fg_color);
>   	return 0;
>   }
> -
> -static int draw_panic_screen_qr_code(struct drm_scanout_buffer *sb,
> -				     u32 fg_color, u32 bg_color,
> -				     unsigned int qr_version)
> -{
> -	if (_draw_panic_screen_qr_code(sb, fg_color, bg_color, qr_version))
> -		draw_panic_screen_user(sb, fg_color, bg_color);
> -	return 0;
> -}
>   #else
>   static void drm_panic_qr_init(void) {};
>   static void drm_panic_qr_exit(void) {};
> @@ -899,13 +890,22 @@ static int draw_panic_dispatch(struct drm_scanout_buffer *sb, enum drm_panic_typ
>   {
>   	int ret;
>   
> +retry:
>   	switch (panic_type) {
>   	case DRM_PANIC_TYPE_KMSG:
>   		ret = draw_panic_screen_kmsg(sb, fg_color, bg_color);
> +		if (ret) {
> +			panic_type = DRM_PANIC_TYPE_USER;
> +			goto retry;
> +		}
>   		break;
>   #if IS_ENABLED(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
>   	case DRM_PANIC_TYPE_QR:
>   		ret = draw_panic_screen_qr_code(sb, fg_color, bg_color, qr_version);
> +		if (ret) {
> +			panic_type = DRM_PANIC_TYPE_USER;
> +			goto retry;
> +		}
>   		break;
>   #endif
>   	case DRM_PANIC_TYPE_USER: