On Tue, Feb 11, 2020 at 07:13:31PM +0200, Ville Syrjälä wrote:
On Tue, Feb 11, 2020 at 06:02:33PM +0100, Daniel Vetter wrote:
On Tue, Feb 11, 2020 at 06:22:06PM +0200, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
Many drivers are populating encoder->possible_clones wrong. Let's persuade them to get it right by adding some loud WARNs.
We'll cross check the bits between any two encoders. So either both encoders can clone with the other, or neither can.
We'll also complain about effectively empty possible_clones, and possible_clones containing bits for encoders that don't exist.
v2: encoder->possible_clones now includes the encoder itelf v3: Move to drm_mode_config_validate() (Daniel) Document that you get a WARN when this is wrong (Daniel) Extract full_encoder_mask()
Acked-by: Thomas Zimmermann tzimmermann@suse.de Cc: Daniel Vetter daniel@ffwll.ch Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
I wonder whether we should start to have some unit tests for stuff like this, like set up broken driver, make sure we have a WARN in dmesg. But ideally we'd do that with the mocking stuff Kunit hopefully has soon.
</idle musings>
drivers/gpu/drm/drm_mode_config.c | 40 +++++++++++++++++++++++++++++++ include/drm/drm_encoder.h | 2 ++ 2 files changed, 42 insertions(+)
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index 75e357c7e84d..afc91447293a 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -533,6 +533,17 @@ void drm_mode_config_cleanup(struct drm_device *dev) } EXPORT_SYMBOL(drm_mode_config_cleanup);
+static u32 full_encoder_mask(struct drm_device *dev) +{
- struct drm_encoder *encoder;
- u32 encoder_mask = 0;
- drm_for_each_encoder(encoder, dev)
encoder_mask |= drm_encoder_mask(encoder);- return encoder_mask;
+}
/*
- For some reason we want the encoder itself included in
- possible_clones. Make life easy for drivers by allowing them
@@ -544,10 +555,39 @@ static void fixup_encoder_possible_clones(struct drm_encoder *encoder) encoder->possible_clones = drm_encoder_mask(encoder); }
+static void validate_encoder_possible_clones(struct drm_encoder *encoder) +{
- struct drm_device *dev = encoder->dev;
- u32 encoder_mask = full_encoder_mask(dev);
- struct drm_encoder *other;
- drm_for_each_encoder(other, dev) {
WARN(!(encoder->possible_clones & drm_encoder_mask(other)) !=!(other->possible_clones & drm_encoder_mask(encoder)),Bikeshed: !! as canonical "make this a bool value" might be slightly clearer, but whatever.
Can repaint.
"possible_clones mismatch: ""[ENCODER:%d:%s] mask=0x%x possible_clones=0x%x vs. ""[ENCODER:%d:%s] mask=0x%x possible_clones=0x%x\n",encoder->base.id, encoder->name,drm_encoder_mask(encoder), encoder->possible_clones,other->base.id, other->name,drm_encoder_mask(other), other->possible_clones);- }
- WARN((encoder->possible_clones & drm_encoder_mask(encoder)) == 0 ||
(encoder->possible_clones & ~encoder_mask) != 0,"Bogus possible_clones: ""[ENCODER:%d:%s] possible_clones=0x%x (full encoder mask=0x%x)\n",encoder->base.id, encoder->name,encoder->possible_clones, encoder_mask);+}
Since it's next to each another double-checking that the fixup did add the self-clone is probably too much :-)
I changed the fixup to be just if (possible_clones == 0) possible_clones = drm_encoder_mask();
So if the driver tries to set it up but fails and forgets the encoder itself this WARN will still trip.
Duh, I was just blind, everything is looking good. -Daniel
void drm_mode_config_validate(struct drm_device *dev) { struct drm_encoder *encoder;
drm_for_each_encoder(encoder, dev) fixup_encoder_possible_clones(encoder);
- drm_for_each_encoder(encoder, dev)
validate_encoder_possible_clones(encoder);} diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h index 22d6cdf729f1..3741963b9587 100644 --- a/include/drm/drm_encoder.h +++ b/include/drm/drm_encoder.h @@ -163,6 +163,8 @@ struct drm_encoder { * any cloning it can leave @possible_clones set to 0. The core will * automagically fix this up by setting the bit for the encoder itself. *
* You will get a WARN if you get this wrong in the driver.Nice.
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
**/
- Note that since encoder objects can't be hotplugged the assigned indices
- are stable and hence known before registering all objects.
-- 2.24.1
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
-- Ville Syrjälä Intel