On Wed, Jun 03, 2020 at 10:45:23AM +0000, Simon Ser wrote:
In update_output_state, the link-status property was reset to GOOD to ensure legacy drmModeSetCrtc re-trains the link. However this auto-reset is also performed on an atomic commit without ALLLOW_MODESET. If a
I didn't think udate_output_state() was getting called for non-legacy paths. Where is that coming from?
driver reads link-status to figure out whether to re-train the link, this could cause an atomic commit failure. User-space doesn't expect such a failure, because commits without ALLOW_MODESET aren't supposed to fail because of link training issues.
Change update_output_state to implicitly reset link-status to GOOD only if ALLOW_MODESET is set. This is the case for legacy drmModeSetCrtc because drm_atomic_state_init sets it (and is used in drm_atomic_helper_set_config, called from drm_mode_setcrtc).
Drivers don't seem to read link-status at the moment -- they seem to rely on user-space performing a modeset instead. So this shouldn't result in any change in behaviour, this should only prevent future failures if drivers start reading link-status.
Signed-off-by: Simon Ser contact@emersion.fr Suggested-by: Pekka Paalanen ppaalanen@gmail.com Cc: Daniel Vetter daniel@ffwll.ch Cc: Manasi Navare manasi.d.navare@intel.com
drivers/gpu/drm/drm_atomic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 965173fd0ac2..3d9d9e6f7397 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -1426,7 +1426,8 @@ static int update_output_state(struct drm_atomic_state *state, return ret;
/* Make sure legacy setCrtc always re-trains */
new_conn_state->link_status = DRM_LINK_STATUS_GOOD;
if (state->allow_modeset)new_conn_state->link_status = DRM_LINK_STATUS_GOOD;-- 2.26.2
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