If the scaling loop in drm_fb_helper_single_fb_probe() only finds
supported depths greater than what it's looking for, it will set
sizes.surface_depth = 0. This broke my udl device:
[drm] test CRTC 0 primary plane
udl 3-9.1:1.0: drm_fb_helper_single_fb_probe: test CRTC 0 format 0, depth=24
udl 3-9.1:1.0: drm_fb_helper_single_fb_probe: 24 > 16, skipping
udl 3-9.1:1.0: drm_fb_helper_single_fb_probe: test CRTC 0 format 1, depth=32
udl 3-9.1:1.0: drm_fb_helper_single_fb_probe: 32 > 16, skipping
[drm] requested bpp 16, scaled depth down to 0
Instead of setting zero depth, print that scaling was not possible and
do nothing.
Fixes: f4bd542bcaee ("drm/fb-helper: Scale back depth to supported maximum")
Signed-off-by: Reza Arbab <ar...@linux.ibm.com>
---
drivers/gpu/drm/drm_fb_helper.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0e9349ff2d16..a7028655a065 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1963,7 +1963,11 @@ static int drm_fb_helper_single_fb_probe(struct
drm_fb_helper *fb_helper,
best_depth = fmt->depth;
}
}
- if (sizes.surface_depth != best_depth) {
+
+ if (!best_depth) {
+ DRM_INFO("Could not scale depth to requested bpp %d",
+ sizes.surface_bpp);
+ } else if (sizes.surface_depth != best_depth) {
DRM_INFO("requested bpp %d, scaled depth down to %d",
sizes.surface_bpp, best_depth);
sizes.surface_depth = best_depth;
--
1.8.3.1
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