Re: [PATCH v2 09/15] drm/fbconv: Mode-setting pipeline enable / disable
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: 2022-05-28 20:18:01
Also in:
dri-devel
Hi Thomas, On Mon, Oct 14, 2019 at 4:05 PM Thomas Zimmermann [off-list ref] wrote:
The display mode is set by converting the DRM display mode to an fb_info state and handling it to the fbdev driver's fb_setvar() function. This also requires a color depth, which we take from the value of struct drm_mode_config.preferred_depth Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
quoted hunk ↗ jump to hunk
--- a/drivers/gpu/drm/drm_fbconv_helper.c +++ b/drivers/gpu/drm/drm_fbconv_helper.c@@ -919,6 +919,24 @@ static int drm_fbconv_update_fb_var_screeninfo_from_framebuffer( return 0; } +static int drm_fbconv_update_fb_var_screeninfo_from_simple_display_pipe( + struct fb_var_screeninfo *fb_var, struct drm_simple_display_pipe *pipe) +{ + struct drm_plane *primary = pipe->crtc.primary; + struct drm_fbconv_modeset *modeset = drm_fbconv_modeset_of_pipe(pipe); + + if (primary && primary->state && primary->state->fb) + return drm_fbconv_update_fb_var_screeninfo_from_framebuffer( + fb_var, primary->state->fb, + modeset->fb_info->fix.smem_len); + + fb_var->xres_virtual = fb_var->xres; + fb_var->yres_virtual = fb_var->yres; + fb_var->bits_per_pixel = modeset->dev->mode_config.preferred_depth;
This looks wrong to me: IMHO bits_per_pixel should be derived from the fourcc format of the _new_ mode to be set...
quoted hunk ↗ jump to hunk
+ + return 0; +} + /** * drm_fbconv_simple_display_pipe_mode_valid - default implementation for * struct drm_simple_display_pipe_funcs.mode_valid@@ -950,6 +968,28 @@ bool drm_fbconv_simple_display_pipe_mode_fixup( struct drm_crtc *crtc, const struct drm_display_mode *mode, struct drm_display_mode *adjusted_mode) { + struct drm_simple_display_pipe *pipe = + container_of(crtc, struct drm_simple_display_pipe, crtc); + struct drm_fbconv_modeset *modeset = drm_fbconv_modeset_of_pipe(pipe); + struct fb_var_screeninfo fb_var; + int ret; + + if (!modeset->fb_info->fbops->fb_check_var) + return true; + + drm_fbconv_init_fb_var_screeninfo_from_mode(&fb_var, mode); + + ret = drm_fbconv_update_fb_var_screeninfo_from_simple_display_pipe( + &fb_var, &modeset->pipe); + if (ret) + return true; + + ret = modeset->fb_info->fbops->fb_check_var(&fb_var, modeset->fb_info);
... hence this fails if the requested mode is valid with the new
fourcc format, but invalid with the old (but preferred) depth.
E.g. due to bandwidth limitations, a high-resolution mode is valid
with a low color depth, while a high color depth is limited to lower
resolutions.
Unfortunately we do not know the new fourcc format here, as both
drm_simple_display_pipe_funcs.mode_{valid,fixup}() are passed
the mode (from drm_mode_set.mode), but not the new format (from
drm_mode_set.fb->format).
Am I missing something? Is the new format available in some other way?
Thanks!
+ if (ret < 0)
+ return false;
+
+ drm_mode_update_from_fb_var_screeninfo(adjusted_mode, &fb_var);
+
return true;
}
EXPORT_SYMBOL(drm_fbconv_simple_display_pipe_mode_fixup);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds