On Tue, Oct 11, 2016 at 04:15:04PM -0700, Stefan Agner wrote:
> The current fbdev emulation does not allow to push back changes in
> width, height or depth to KMS, hence reject any changes with an
> error. This makes sure that fbdev ioctl's fail properly and user
> space does not assume that changes succeeded.
>
> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
Make sense to me, but would be great to have an r-b from someone who has
some clue about fbdev ... Tomi, Laurent?
-Daniel
> ---
> This rejects reconfiguration of framebuffer like
> fbset -rgba 5,6,5 -depth 16 (when in 24 bit mode by default)
> fbset -xres 123
>
> I think all users of drm_fb_helper_check_var use also the generic
> drm_fb_helper_set_par (or do otherwise not support changing size/
> depth). Hence, afaict, the change should be the right thing to do
> for all driver...
>
> drivers/gpu/drm/drm_fb_helper.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 03414bd..596c056 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -1211,11 +1211,14 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
> if (var->pixclock != 0 || in_dbg_master())
> return -EINVAL;
>
> - /* Need to resize the fb object !!! */
> - if (var->bits_per_pixel > fb->bits_per_pixel ||
> - var->xres > fb->width || var->yres > fb->height ||
> - var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
> - DRM_DEBUG("fb userspace requested width/height/bpp is greater than current fb "
> + /*
> + * 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->bits_per_pixel ||
> + var->xres != fb->width || var->yres != fb->height ||
> + var->xres_virtual != fb->width || var->yres_virtual != fb->height) {
> + DRM_DEBUG("fb userspace requested width/height/bpp different than current fb "
> "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
> var->xres, var->yres, var->bits_per_pixel,
> var->xres_virtual, var->yres_virtual,
> --
> 2.10.0
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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