[Intel-gfx] [PATCH 1/2] drm/i915: Only break encoder linked when linked to connector

[Chris Wilson]

On Mon, Apr 14, 2014 at 07:26:08PM +0200, Egbert Eich wrote:
> Depending on the SDVO output_flags SDVO may have multiple connectors
> linking to the same encoder (in intel_connector->encoder->base).
> Only one of those connectors should be active (ie link to the encoder
> thru drm_connector->encoder.
> If intel_connector_break_all_links() is called from intel_sanitize_crtc()
> we may brake the crtc connection of an encoder thru an inactive connector
> in which case intel_connector_break_all_links() will not be called again
> for the active connector due to
>    if (connector->encoder->base.crtc != &crtc->base)
>                                 continue;
> in intel_sanitize_crtc().
> This will however leave the drm_connector->encoder linkage for this
> active connector in place. Subsequently this will cause multiple
> warnings in intel_connector_check_state() to trigger and the driver
> will eventually die in drm_encoder_crtc_ok() (because of crtc == NULL).
> 
> To avoid this break the encoder links only if the connector is active
> (ie. has drm_connector->encoder set).
> 
> Signed-off-by: Egbert Eich <eich at suse.de>

This just leaves me with a nagging doubt that not all links will then be
broken. Do we have sufficient sanity checks to detect the obverse? Would
it be worth adding a second pass over the connector_list to assert that
all links are then broken?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre