Hello All,
I bumped into the below check [1] enforced in drm_framebuffer creation which checks the requested framebuffer width/height parameters against the drm mode config width/height limits. As I understand, drm_mode_config: min/max width/height indicate the upper and lower bounds of the display panel (drm_connector) resolutions the DRM device can support. But the pixel processing pipeline can apply cropping/scaling transformations on much larger input framebuffers and flip the buffers within the display resolution. Such configurations are very common and the final resolution will be still within drm_mode_config bounds. So I believe the checks should be relaxed / removed from the drm_framebuffer creation api's.
If my understanding is incorrect, could somehow explain the motivation behind having these checks here?
Thanks and Regards,
Jeykumar S.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/driv ers/gpu/drm/drm_framebuffer.c?h=v5.3#n303
struct drm_framebuffer * drm_internal_framebuffer_create(struct drm_device *dev, const struct drm_mode_fb_cmd2 *r, struct drm_file *file_priv) {
/* snip */
if ((config->min_width > r->width) || (r->width > config->max_width)) {
DRM_DEBUG_KMS("bad framebuffer width %d, should be >= %d && <= %d\n",
r->width, config->min_width, config->max_width);
return ERR_PTR(-EINVAL);
}
if ((config->min_height > r->height) || (r->height > config->max_height)) {
DRM_DEBUG_KMS("bad framebuffer height %d, should be >= %d && <= %d\n",
r->height, config->min_height, config->max_height);
return ERR_PTR(-EINVAL);
}
/* snip */
}