Hello,
On Wed, Oct 28, 2020 at 08:04:53PM +0530, Nikhil Devshatwar wrote:
On 14:31-20201021, Tomi Valkeinen wrote:
On 16/10/2020 13:39, Nikhil Devshatwar wrote:
When the next bridge does not specify any bus flags, use the bridge->timings->input_bus_flags as fallback when propagating bus flags from next bridge to current bridge.
Signed-off-by: Nikhil Devshatwar nikhil.nd@ti.com
drivers/gpu/drm/drm_bridge.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 64f0effb52ac..8353723323ab 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -975,6 +975,13 @@ drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge, * duplicate the "dummy propagation" logic. */ bridge_state->input_bus_cfg.flags = output_flags;
- /*
* Use the bridge->timings->input_bus_flags as fallback if the next bridge* does not specify the flags*/- if (!bridge_state->input_bus_cfg.flags)
bridge_state->input_bus_cfg.flags = bridge->timings->input_bus_flags;According to docs, timings can be NULL.
Correct.
And, hmm... It's too easy to get confused with these, but... If the bridge defines timings, and timings->input_bus_flags != 0, should we always pick that, even if we got something via output_flags? Logic being, if this bridge defines timings->input_bus_flags, it probably wants that to be used regardless whether we got something from the next bridge.
timings->input_bus_flags is an API that predates format and flags propagation along the pipeline. I would assume that drivers that implement propagation should do so in a way that prioritize that API, and either not report flags in the timings (in which case giving priority to one or another wouldn't make a difference as both would never be provided together), or would report flags in the timings as a best effort fallback for display controller drivers that would look at them exclusively without supporting the new API. I would thus think that the flags obtained through format negotiation should be prioritized.
Got it, the flags from timings if present should be prioritized rather than treating them as fallback.