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Message-ID: <24ba6014-ce85-9013-fa89-17a4c7fcfc21@suse.de>
Date: Thu, 31 Aug 2023 10:57:28 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Geert Uytterhoeven <geert@...ux-m68k.org>,
Javier Martinez Canillas <javierm@...hat.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 7/8] drm/fb-helper: Add support for DRM_FORMAT_R1
Hi
Am 24.08.23 um 17:08 schrieb Geert Uytterhoeven:
> Add support for the monochrome light-on-dark buffer format (R1) to the
> fb helper, so this format can be used for fbdev emulation and for the
> text console. This avoids the overhead of using XR24 and the associated
> conversions on display hardware that supports only a simple monochrome
> format.
>
> R1 is very similar to C1 (monochrome indexed color), and shares the same
> depth and bpp. As drm_mode_legacy_fb_format() returns a format based on
> only depth and bpp, it cannot distinguish between R1 and C1. Hence
Could we rather add another parameter to drm_mode_legacy_fb_format();
say 'bool indexed'. If set to true, it prefers _Cx formats, otherwise _Rx.
The parameter would be 'true' for most calls; except in
drm_fb_helper_find_format(). There, we can go through the array of given
formats and check if there's one that has is_color_indexed set. If so,
we specify true, if not we specify false.
Best regards
Thomas
> drm_fb_helper_find_format() is modified to try to fall back to R1 if C1
> is not supported.
>
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>
> Tested-by: Javier Martinez Canillas <javierm@...hat.com>
> ---
> v2:
> - Add Reviewed-by, Tested-by.
> ---
> drivers/gpu/drm/drm_fb_helper.c | 41 ++++++++++++++++++++++++---------
> 1 file changed, 30 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 4dc28fdcc1e0a6a4..71baf8597516e9fd 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -1130,7 +1130,7 @@ static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
> {
> u8 depth = format->depth;
>
> - if (format->is_color_indexed) {
> + if (format->format == DRM_FORMAT_R1 || format->is_color_indexed) {
> var->red.offset = 0;
> var->green.offset = 0;
> var->blue.offset = 0;
> @@ -1236,6 +1236,7 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
> case DRM_FORMAT_C1:
> case DRM_FORMAT_C2:
> case DRM_FORMAT_C4:
> + case DRM_FORMAT_R1:
> /* supported format with sub-byte pixels */
> break;
>
> @@ -1439,12 +1440,24 @@ int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
> }
> EXPORT_SYMBOL(drm_fb_helper_pan_display);
>
> +static bool is_supported_format(uint32_t format, const uint32_t *formats,
> + size_t format_count)
> +{
> + size_t i;
> +
> + for (i = 0; i < format_count; ++i) {
> + if (formats[i] == format)
> + return true;
> + }
> +
> + return false;
> +}
> +
> static uint32_t drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const uint32_t *formats,
> size_t format_count, uint32_t bpp, uint32_t depth)
> {
> struct drm_device *dev = fb_helper->dev;
> uint32_t format;
> - size_t i;
>
> /*
> * Do not consider YUV or other complicated formats
> @@ -1457,10 +1470,12 @@ static uint32_t drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const
> if (!format)
> goto err;
>
> - for (i = 0; i < format_count; ++i) {
> - if (formats[i] == format)
> - return format;
> - }
> + if (is_supported_format(format, formats, format_count))
> + return format;
> +
> + if (format == DRM_FORMAT_C1 &&
> + is_supported_format(DRM_FORMAT_R1, formats, format_count))
> + return DRM_FORMAT_R1;
>
> err:
> /* We found nothing. */
> @@ -1680,11 +1695,15 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
> }
>
> static void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
> - bool is_color_indexed)
> + const struct drm_format_info *format)
> {
> info->fix.type = FB_TYPE_PACKED_PIXELS;
> - info->fix.visual = is_color_indexed ? FB_VISUAL_PSEUDOCOLOR
> - : FB_VISUAL_TRUECOLOR;
> + if (format->format == DRM_FORMAT_R1)
> + info->fix.visual = FB_VISUAL_MONO10;
> + else if (format->is_color_indexed)
> + info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
> + else
> + info->fix.visual = FB_VISUAL_TRUECOLOR;
> info->fix.mmio_start = 0;
> info->fix.mmio_len = 0;
> info->fix.type_aux = 0;
> @@ -1707,6 +1726,7 @@ static void drm_fb_helper_fill_var(struct fb_info *info,
> case DRM_FORMAT_C1:
> case DRM_FORMAT_C2:
> case DRM_FORMAT_C4:
> + case DRM_FORMAT_R1:
> /* supported format with sub-byte pixels */
> break;
>
> @@ -1747,8 +1767,7 @@ void drm_fb_helper_fill_info(struct fb_info *info,
> {
> struct drm_framebuffer *fb = fb_helper->fb;
>
> - drm_fb_helper_fill_fix(info, fb->pitches[0],
> - fb->format->is_color_indexed);
> + drm_fb_helper_fill_fix(info, fb->pitches[0], fb->format);
> drm_fb_helper_fill_var(info, fb_helper,
> sizes->fb_width, sizes->fb_height);
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
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