Re: [PATCH] lib/igt_kms: Do not treat writeback and virtual connectors as connected

Hi S,,
On 2026-08-21 at 03:53:30 +0000, S, Sowmiya wrote:
> Hi @Mark Yacoub
> 
> > -----Original Message-----
> > From: igt-dev <[email protected]> On Behalf Of Mark
> > Yacoub
> > Sent: 20 August 2026 00:38
> > To: [email protected]
> > Cc: Mark Yacoub <[email protected]>
> > Subject: [PATCH] lib/igt_kms: Do not treat writeback and virtual connectors as
> > connected
> > 
> > Writeback and virtual connectors (e.g. DRM_MODE_CONNECTOR_WRITEBACK
> > and
> > DRM_MODE_CONNECTOR_VIRTUAL) do not represent physical display sinks
> > and cannot be modeset using standard CRTC / atomic commit operations
> > without configuring a writeback output framebuffer (WRITEBACK_FB_ID).
> > 
> > On drivers such as MSM, writeback connectors (e.g. Virtual-1, Virtual-2) report
> > connected status with virtual modes. When generic KMS tests iterate over
> > connected outputs via for_each_connected_output() or during initial display
> > setup in igt_display_init(), attempting standard modesets on these connectors
> > causes failures (-EINVAL) before test execution can begin.
> > 
> > Exclude DRM_MODE_CONNECTOR_WRITEBACK and
> > DRM_MODE_CONNECTOR_VIRTUAL in
> > igt_output_is_connected() so generic KMS tests only target standard physical
> > display outputs, while dedicated writeback tests can continue to iterate all
> > outputs explicitly via for_each_output().
> > 
> > Signed-off-by: Mark Yacoub <[email protected]>
> > ---
> >  lib/igt_kms.h | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/lib/igt_kms.h b/lib/igt_kms.h index 521a03c01..8d4d14847 100644
> > --- a/lib/igt_kms.h
> > +++ b/lib/igt_kms.h
> > @@ -668,6 +668,10 @@ static inline bool
> > igt_output_is_connected(igt_output_t *output)
> >  	    !output->config.connector->count_modes)
> >  		return false;
> > 
> > +	if (output->config.connector->connector_type ==
> > DRM_MODE_CONNECTOR_WRITEBACK ||
> > +	    output->config.connector->connector_type ==
> > DRM_MODE_CONNECTOR_VIRTUAL)
> > +		return false;
> > +
> writeback tests already bypass igt_output_is_connected() by
> design and continue to work via for_each_output(), while
> generic tests correctly stop trying to modeset
> writeback/virtual connectors.
> LGTM,
> Reviewed-by: Sowmiya S <[email protected]>

Applied, thank you all.

Regards,
Kamil

> 
> >  	if (output->config.connector->connection ==
> > DRM_MODE_CONNECTED)
> >  		return true;
> > 
> > --
> > 2.55.0.737.g08866a6d13-goog
>