On Tue, Jul 21, 2026 at 02:52:27PM +0100, Raveendra Talabattula wrote: > Komeda leaves encoder->possible_clones unset, so it stays at 0 for every > encoder. When userspace asks for writeback, the DRM atomic checks
Can you tell me more about this? What are you trying to do with the writeback? Please note that there is a patch series that changes the way encoders get created for the writeback connectors, so that can potentially affect your use case. > reject the configuration because no encoder is marked as clone-compatible, > leading to errors such as: > > crtc96 failed valid clone check for mask 0x5 The error you're seeing here is due to the encoder having a non-zero "possible_clones" which shows there is an error in your setup earlier and nothing to do with komeda. > > Komeda does not impose per-encoder clone restrictions, [...] Komeda doesn't care about the encoders at all as it is meant to be agnostic to whatever encoder is used. > [...] so initialize > possible_clones for all registered encoders to the full encoder mask > after encoder creation. This fixes writeback validation. > > Signed-off-by: Asad Malik <[email protected]> > Signed-off-by: Raveendra Talabattula <[email protected]> > --- > .../gpu/drm/arm/display/komeda/komeda_kms.c | 20 +++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c > b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c > index 6ed504099188..0dcc8c05e86b 100644 > --- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c > @@ -276,7 +276,10 @@ struct komeda_kms_dev *komeda_kms_attach(struct > komeda_dev *mdev) > { > struct komeda_kms_dev *kms; > struct drm_device *drm; > + struct drm_encoder *encoder; > int err; > + /* Bitmap of all encoders, assigned to each encoder's possible_clones. > */ > + u32 clone_mask = 0; > > kms = devm_drm_dev_alloc(mdev->dev, &komeda_kms_driver, > struct komeda_kms_dev, base); > @@ -311,6 +314,23 @@ struct komeda_kms_dev *komeda_kms_attach(struct > komeda_dev *mdev) > > drm_mode_config_reset(drm); > > + /* > + * Build the full possible_clones mask once. drm_encoder_index() > + * returns the bit position assigned to each encoder and BIT() converts > + * that index into the corresponding mask value. > + * > + * Komeda does not have per-encoder clone restrictions, so every encoder > + * gets the same mask and is advertised as clone-compatible with all > + * other registered encoders. > + */ > + drm_for_each_encoder(encoder, drm) { > + clone_mask |= BIT(drm_encoder_index(encoder)); > + } > + > + drm_for_each_encoder(encoder, drm) { > + encoder->possible_clones = clone_mask; > + } You're modifying all the encoders in the system here which is not the right thing. Best regards, Liviu > + > err = devm_request_irq(drm->dev, mdev->irq, > komeda_kms_irq_handler, IRQF_SHARED, > drm->driver->name, drm); > -- > 2.43.0 > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯
