[PATCH 1/7] drm: Don't overwrite UNVERFIED mode status to OK

[Ville Syrjälä]

On Fri, Dec 04, 2015 at 09:17:28AM +0100, Daniel Vetter wrote:
> On Thu, Dec 03, 2015 at 11:14:09PM +0200, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > The way the mode probing works is this:
> > 1. All modes currently on the mode list are marked as UNVERIFIED
> > 2. New modes are on the probed_modes list (they start with
> >    status OK)
> > 3. Modes are moved from the probed_modes list to the actual
> >    mode list. If a mode already on the mode list is deemed
> >    to match one of the probed modes, the duplicate is dropped
> >    and the mode status updated to OK. After this the
> >    probed_modes list will be empty.
> > 4. All modes on the mode list are verified to not violate any
> >    constraints. Any that do are marked as such.
> > 5. Any mode left with a non-OK status is pruned from the list,
> >    with an appropriate debug message.
> 
> This would look really pretty as a kerneldoc addition to
> probe_single_connector(). And with asciidoc we can even do pretty ordered
> lists like these. Can you please follow-up with a patch for that?
> 
> > 
> > What all this means is that any mode on the original list that
> > didn't have a duplicate on the probed_modes list, should be left
> > with status UNVERFIED (or previously could have been left with
> > some other status, but never OK).
> > 
> > I broke that in
> > commit 05acaec334fc ("drm: Reorganize probed mode validation")
> > by always assigning something to the mode->status during the validation
> > step. So any mode from the old list that still passed the validation
> > would be left on the list with status OK in the end.
> > 
> > Fix this by not doing the basic mode validation unless the mode
> > already has status OK (meaning it came from the probed_modes list,
> > or at least a duplicate of it was on that list). This way we will
> > correctly prune away any mode from the old mode list that didn't
> > appear on the probed_modes list.
> > 
> > Cc: stable at vger.kernel.org
> > Cc: Adam Jackson <ajax at redhat.com>
> > Fixes: 05acaec334fc ("drm: Reorganize probed mode validation")
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Testcase: igt/kms_force_connector_basic/prune-stale-modes
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93332

> 
> > ---
> >  drivers/gpu/drm/drm_probe_helper.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> > index 94ba39e34299..b9b3bd9349ff 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -229,7 +229,8 @@ static int drm_helper_probe_single_connector_modes_merge_bits(struct drm_connect
> >  		mode_flags |= DRM_MODE_FLAG_3D_MASK;
> >  
> >  	list_for_each_entry(mode, &connector->modes, head) {
> > -		mode->status = drm_mode_validate_basic(mode);
> > +		if (mode->status == MODE_OK)
> > +			mode->status = drm_mode_validate_basic(mode);
> >  
> >  		if (mode->status == MODE_OK)
> >  			mode->status = drm_mode_validate_size(mode, maxX, maxY);
> > -- 
> > 2.4.10
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel OTC