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 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; } }
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 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
I think we should have Cc: stable@vger.kernel.org on this. Also I think would be really awesome if we can update/extend the igt, but I guess if you don't have a chamelium it's a bit hard to make that happen :-/
Also I guess you'll reflect this in your doc patch?
With the cc: stable this has my Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
Cheers, Daniel
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
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
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
On Wed, Jun 03, 2020 at 02:13:43PM +0300, Ville Syrjälä wrote:
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?
Oops, I'm blind and you're right, there's no bug. We already only force-set this for legacy modeset (and fbcon).
That also means that atomic userspace has to handle this, which is maybe not so awesome ... So maybe we need to duct-tape over this for atomic too, and in that case it should be only done when ALLOW_MODESET is set.
But maybe all the compositors that care will handle this :-/ -Daniel
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
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- Ville Syrjälä Intel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
On Wednesday, June 3, 2020 1:36 PM, Daniel Vetter daniel@ffwll.ch wrote:
On Wed, Jun 03, 2020 at 02:13:43PM +0300, Ville Syrjälä wrote:
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?
Oops, I'm blind and you're right, there's no bug. We already only force-set this for legacy modeset (and fbcon).
Indeed, good catch Ville. set_config is purely a legacy thing.
That also means that atomic userspace has to handle this, which is maybe not so awesome ... So maybe we need to duct-tape over this for atomic too, and in that case it should be only done when ALLOW_MODESET is set.
But maybe all the compositors that care will handle this :-/
Not fond of this because we'll basically end up with some drivers checking for link-status (none do that yet) and some user-space resetting it to GOOD. It'll break only if user-space doesn't reset and a driver which checks link-status is used. Driver-specific behaviour isn't great.
On Wed, Jun 03, 2020 at 01:17:14PM +0000, Simon Ser wrote:
On Wednesday, June 3, 2020 1:36 PM, Daniel Vetter daniel@ffwll.ch wrote:
On Wed, Jun 03, 2020 at 02:13:43PM +0300, Ville Syrjälä wrote:
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?
Oops, I'm blind and you're right, there's no bug. We already only force-set this for legacy modeset (and fbcon).
Indeed, good catch Ville. set_config is purely a legacy thing.
That also means that atomic userspace has to handle this, which is maybe not so awesome ... So maybe we need to duct-tape over this for atomic too, and in that case it should be only done when ALLOW_MODESET is set.
But maybe all the compositors that care will handle this :-/
Not fond of this because we'll basically end up with some drivers checking for link-status (none do that yet) and some user-space resetting it to GOOD. It'll break only if user-space doesn't reset and a driver which checks link-status is used. Driver-specific behaviour isn't great.
See my other reply, drivers don't need to check for GOOD, it's kinda magic. -Daniel
dri-devel@lists.freedesktop.org
-
Daniel Vetter -
Simon Ser -
Ville Syrjälä