Re: [PATCH 3/5] drm: bridge: Propagate the bus flags from bridge->timings

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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.

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.

 Tomi

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