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authorGeert Uytterhoeven <geert+renesas@glider.be>2019-12-30 14:27:34 +0100
committerDaniel Vetter <daniel.vetter@ffwll.ch>2020-01-07 16:54:03 +0100
commitf30e27779d3031a092c2a177b7fb76adccc45241 (patch)
treec730ac17c19d60e35cde9e33b52372dcd3df9a79
parent4396393fb96449c56423fb4b351f76e45a6bcaf6 (diff)
drm/fb-helper: Round up bits_per_pixel if possibledrm-misc-fixes-2020-01-08
When userspace requests a video mode parameter value that is not supported, frame buffer device drivers should round it up to a supported value, if possible, instead of just rejecting it. This allows applications to quickly scan for supported video modes. Currently this rule is not followed for the number of bits per pixel, causing e.g. "fbset -depth N" to fail, if N is smaller than the current number of bits per pixel. Fix this by returning an error only if bits per pixel is too large, and setting it to the current value otherwise. See also Documentation/fb/framebuffer.rst, Section 2 (Programmer's View of /dev/fb*"). Fixes: 865afb11949e5bf4 ("drm/fb-helper: reject any changes to the fbdev") Cc: stable@vger.kernel.org Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20191230132734.4538-1-geert+renesas@glider.be
-rw-r--r--drivers/gpu/drm/drm_fb_helper.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 8ebeccdeed23..d8e8f3960f4d 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1283,7 +1283,7 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
* Changes struct fb_var_screeninfo are currently not pushed back
* to KMS, hence fail if different settings are requested.
*/
- if (var->bits_per_pixel != fb->format->cpp[0] * 8 ||
+ if (var->bits_per_pixel > fb->format->cpp[0] * 8 ||
var->xres > fb->width || var->yres > fb->height ||
var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
DRM_DEBUG("fb requested width/height/bpp can't fit in current fb "
@@ -1309,6 +1309,11 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
}
/*
+ * Likewise, bits_per_pixel should be rounded up to a supported value.
+ */
+ var->bits_per_pixel = fb->format->cpp[0] * 8;
+
+ /*
* drm fbdev emulation doesn't support changing the pixel format at all,
* so reject all pixel format changing requests.
*/