Re: [PATCH 05/12] drm/panic: Pass colors to draw_panic_dispatch()

[Jocelyn Falempe <jfalempe@redhat.com>]

On 18/08/2026 14:28, Thomas Zimmermann wrote:
> Set the panic-screen colors in draw_panic_plane() as a single point
> of truth. Pass the values into the individual drawing functions.
> 
> In the test cases, replace the Kconfig-defined colors with white and
> black. Allows for removal of the tests' limitations and dependency on
> the exact values. All tests now always verify the generated output.
> 
> Hardcoding the test colors will later also allow for building the
> test case without having DRM panic handling enabled.

Thanks, that makes sense, I should've think about it, as this colors was 
a bit painful when writing the KUnit tests.

Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>   drivers/gpu/drm/drm_panic.c            | 54 +++++++++++++++-----------
>   drivers/gpu/drm/tests/drm_panic_test.c | 26 +++++++++----
>   2 files changed, 49 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
> index 594235661710..ede620b27515 100644
> --- a/drivers/gpu/drm/drm_panic.c
> +++ b/drivers/gpu/drm/drm_panic.c
> @@ -478,12 +478,8 @@ static void drm_panic_logo_draw(struct drm_scanout_buffer *sb, struct drm_rect *
>   				   fg_color);
>   }
>   
> -static int draw_panic_screen_user(struct drm_scanout_buffer *sb)
> +static int draw_panic_screen_user(struct drm_scanout_buffer *sb, u32 fg_color, u32 bg_color)
>   {
> -	u32 fg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR,
> -						    sb->format->format);
> -	u32 bg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR,
> -						    sb->format->format);
>   	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
>   	struct drm_rect r_screen, r_logo, r_msg;
>   	unsigned int msg_width, msg_height;
> @@ -491,6 +487,9 @@ static int draw_panic_screen_user(struct drm_scanout_buffer *sb)
>   	if (!font)
>   		return -EINVAL;
>   
> +	fg_color = drm_draw_color_from_xrgb8888(fg_color, sb->format->format);
> +	bg_color = drm_draw_color_from_xrgb8888(bg_color, sb->format->format);
> +
>   	r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
>   	drm_panic_logo_rect(&r_logo, font);
>   
> @@ -549,12 +548,8 @@ static int draw_line_with_wrap(struct drm_scanout_buffer *sb, const struct font_
>    * Draw the kmsg buffer to the screen, starting from the youngest message at the bottom,
>    * and going up until reaching the top of the screen.
>    */
> -static int draw_panic_screen_kmsg(struct drm_scanout_buffer *sb)
> +static int draw_panic_screen_kmsg(struct drm_scanout_buffer *sb, u32 fg_color, u32 bg_color)
>   {
> -	u32 fg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR,
> -						    sb->format->format);
> -	u32 bg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR,
> -						    sb->format->format);
>   	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
>   	struct drm_rect r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
>   	struct kmsg_dump_iter iter;
> @@ -566,6 +561,9 @@ static int draw_panic_screen_kmsg(struct drm_scanout_buffer *sb)
>   	if (!font || font->width > sb->width)
>   		return -EINVAL;
>   
> +	fg_color = drm_draw_color_from_xrgb8888(fg_color, sb->format->format);
> +	bg_color = drm_draw_color_from_xrgb8888(bg_color, sb->format->format);
> +
>   	yoffset = sb->height - font->height - (sb->height % font->height) / 2;
>   
>   	/* Fill with the background color, and draw text on top */
> @@ -748,12 +746,9 @@ static int drm_panic_get_qr_code(u8 **qr_image)
>   /*
>    * 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)
> +static int _draw_panic_screen_qr_code(struct drm_scanout_buffer *sb,
> +				      u32 fg_color, u32 bg_color)
>   {
> -	u32 fg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR,
> -						    sb->format->format);
> -	u32 bg_color = drm_draw_color_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR,
> -						    sb->format->format);
>   	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;
>   	unsigned int max_qr_size, scale;
> @@ -766,6 +761,9 @@ static int _draw_panic_screen_qr_code(struct drm_scanout_buffer *sb)
>   	if (!font)
>   		return -EINVAL;
>   
> +	fg_color = drm_draw_color_from_xrgb8888(fg_color, sb->format->format);
> +	bg_color = drm_draw_color_from_xrgb8888(bg_color, sb->format->format);
> +
>   	r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
>   
>   	drm_panic_logo_rect(&r_logo, font);
> @@ -818,10 +816,10 @@ static int _draw_panic_screen_qr_code(struct drm_scanout_buffer *sb)
>   	return 0;
>   }
>   
> -static int draw_panic_screen_qr_code(struct drm_scanout_buffer *sb)
> +static int draw_panic_screen_qr_code(struct drm_scanout_buffer *sb, u32 fg_color, u32 bg_color)
>   {
> -	if (_draw_panic_screen_qr_code(sb))
> -		draw_panic_screen_user(sb);
> +	if (_draw_panic_screen_qr_code(sb, fg_color, bg_color))
> +		draw_panic_screen_user(sb, fg_color, bg_color);
>   	return 0;
>   }
>   #else
> @@ -893,22 +891,22 @@ static bool drm_panic_is_format_supported(const struct drm_format_info *format)
>   	return drm_draw_can_convert_from_xrgb8888(format->format);
>   }
>   
> -static int draw_panic_dispatch(struct drm_scanout_buffer *sb)
> +static int draw_panic_dispatch(struct drm_scanout_buffer *sb, u32 fg_color, u32 bg_color)
>   {
>   	int ret;
>   
>   	switch (drm_panic_type) {
>   	case DRM_PANIC_TYPE_KMSG:
> -		ret = draw_panic_screen_kmsg(sb);
> +		ret = draw_panic_screen_kmsg(sb, fg_color, bg_color);
>   		break;
>   #if IS_ENABLED(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
>   	case DRM_PANIC_TYPE_QR:
> -		ret = draw_panic_screen_qr_code(sb);
> +		ret = draw_panic_screen_qr_code(sb, fg_color, bg_color);
>   		break;
>   #endif
>   	case DRM_PANIC_TYPE_USER:
>   	default:
> -		ret = draw_panic_screen_user(sb);
> +		ret = draw_panic_screen_user(sb, fg_color, bg_color);
>   	}
>   
>   	return ret;
> @@ -943,6 +941,16 @@ static void draw_panic_plane(struct drm_plane *plane, const char *description)
>   	struct drm_scanout_buffer sb = { };
>   	int ret;
>   	unsigned long flags;
> +#if defined(CONFIG_DRM_PANIC_FOREGROUND_COLOR)
> +	u32 fg_color = CONFIG_DRM_PANIC_FOREGROUND_COLOR;
> +#else
> +	u32 fg_color = 0x00ffffff;
> +#endif
> +#if defined(CONFIG_DRM_PANIC_BACKGROUND_COLOR)
> +	u32 bg_color = CONFIG_DRM_PANIC_BACKGROUND_COLOR;
> +#else
> +	u32 bg_color = 0x00000000;
> +#endif
>   
>   	if (!drm_panic_trylock(plane->dev, flags))
>   		return;
> @@ -958,7 +966,7 @@ static void draw_panic_plane(struct drm_plane *plane, const char *description)
>   
>   	drm_panic_set_description(description);
>   
> -	ret = draw_panic_dispatch(&sb);
> +	ret = draw_panic_dispatch(&sb, fg_color, bg_color);
>   	if (!ret) {
>   		/*
>   		 * Only flush if we have a panic screen to display. Otherwise
> diff --git a/drivers/gpu/drm/tests/drm_panic_test.c b/drivers/gpu/drm/tests/drm_panic_test.c
> index fdd77b0cc54c..969a096ec840 100644
> --- a/drivers/gpu/drm/tests/drm_panic_test.c
> +++ b/drivers/gpu/drm/tests/drm_panic_test.c
> @@ -14,17 +14,10 @@
>   #include <linux/units.h>
>   #include <linux/vmalloc.h>
>   
> -/* Check the framebuffer color only if the panic colors are the default */
> -#if (CONFIG_DRM_PANIC_BACKGROUND_COLOR == 0 && \
> -	CONFIG_DRM_PANIC_FOREGROUND_COLOR == 0xffffff)
> -
>   static void drm_panic_check_color_byte(struct kunit *test, u8 b)
>   {
>   	KUNIT_EXPECT_TRUE(test, (b == 0 || b == 0xff));
>   }
> -#else
> -static void drm_panic_check_color_byte(struct kunit *test, u8 b) {}
> -#endif
>   
>   struct drm_test_mode {
>   	const int width;
> @@ -48,10 +41,27 @@ struct drm_test_mode {
>   	.width = w, \
>   	.height = h, \
>   	.format = f, \
> -	.draw_screen = draw_panic_screen_##name, \
> +	.draw_screen = draw_panic_screen_ ## name ## _default, \
>   	.fname = #name, \
>   	}, \
>   
> +static int draw_panic_screen_user_default(struct drm_scanout_buffer *sb)
> +{
> +	return draw_panic_screen_user(sb, 0x00ffffff, 0x00000000);
> +}
> +
> +static int draw_panic_screen_kmsg_default(struct drm_scanout_buffer *sb)
> +{
> +	return draw_panic_screen_kmsg(sb, 0x00ffffff, 0x00000000);
> +}
> +
> +#if IS_ENABLED(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
> +static int draw_panic_screen_qr_code_default(struct drm_scanout_buffer *sb)
> +{
> +	return draw_panic_screen_qr_code(sb, 0x00ffffff, 0x00000000);
> +}
> +#endif
> +
>   static const struct drm_test_mode drm_test_modes_cases[] = {
>   	DRM_TEST_MODE_LIST(user)
>   	DRM_TEST_MODE_LIST(kmsg)