Re: [PATCH v3 4/6] drm/tidss: Set bus_format correctly from bridge/connector

[Nikhil Devshatwar <nikhil.nd@ti.com>]

On 11:45-20201130, Laurent Pinchart wrote:
> Hi Nikhil,
> 
> Thank you for the patch.
> 
> On Thu, Nov 19, 2020 at 09:31:32PM +0530, Nikhil Devshatwar wrote:
> > Remove the old code to iterate over the bridge chain, as this is
> > already done by the framework.
> > The bridge state should have the negotiated bus format and flags.
> > Use these from the bridge's state.
> > If the bridge does not support format negotiation, error out
> > and fail.
> > 
> > Signed-off-by: Nikhil Devshatwar <nikhil.nd@ti.com>
> > Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> > ---
> > 
> > Notes:
> >     changes from v2:
> >     * Remove the old code and use the flags from the bridge state
> > 
> >  drivers/gpu/drm/tidss/tidss_encoder.c | 36 +++++++++++----------------
> >  1 file changed, 14 insertions(+), 22 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/tidss/tidss_encoder.c b/drivers/gpu/drm/tidss/tidss_encoder.c
> > index e278a9c89476..08d5083c5508 100644
> > --- a/drivers/gpu/drm/tidss/tidss_encoder.c
> > +++ b/drivers/gpu/drm/tidss/tidss_encoder.c
> > @@ -21,37 +21,29 @@ static int tidss_encoder_atomic_check(struct drm_encoder *encoder,
> >  {
> >  	struct drm_device *ddev = encoder->dev;
> >  	struct tidss_crtc_state *tcrtc_state = to_tidss_crtc_state(crtc_state);
> > -	struct drm_display_info *di = &conn_state->connector->display_info;
> > +	struct drm_bridge_state *bstate;
> >  	struct drm_bridge *bridge;
> > -	bool bus_flags_set = false;
> >  
> >  	dev_dbg(ddev->dev, "%s\n", __func__);
> >  
> > -	/*
> > -	 * Take the bus_flags from the first bridge that defines
> > -	 * bridge timings, or from the connector's display_info if no
> > -	 * bridge defines the timings.
> > -	 */
> > -	drm_for_each_bridge_in_chain(encoder, bridge) {
> > -		if (!bridge->timings)
> > -			continue;
> > -
> > -		tcrtc_state->bus_flags = bridge->timings->input_bus_flags;
> > -		bus_flags_set = true;
> > -		break;
> > +	/* Copy the bus_format and flags from the first bridge's state */
> > +	bridge = drm_bridge_chain_get_first_bridge(encoder);
> > +	bstate = drm_atomic_get_new_bridge_state(crtc_state->state, bridge);
> > +	if (bstate) {
> > +		tcrtc_state->bus_format = bstate->input_bus_cfg.format;
> > +		tcrtc_state->bus_flags = bstate->input_bus_cfg.flags;
> > +	} else {
> > +		dev_err(ddev->dev, "Could not get the bridge state\n");
> > +		return -EINVAL;
> >  	}
> 
> I'd write this
> 
> 	bstate = drm_atomic_get_new_bridge_state(crtc_state->state, bridge);
> 	if (!bstate) {
> 		dev_err(ddev->dev, "Could not get the bridge state\n");
> 		return -EINVAL;
> 	}
> 
> 	tcrtc_state->bus_format = bstate->input_bus_cfg.format;
> 	tcrtc_state->bus_flags = bstate->input_bus_cfg.flags;

Looks better this way. I'll update

Nikhil Devshatwar

> >  
> > -	if (!di->bus_formats || di->num_bus_formats == 0)  {
> > -		dev_err(ddev->dev, "%s: No bus_formats in connected display\n",
> > -			__func__);
> > +	if (tcrtc_state->bus_format == 0 ||
> > +	    tcrtc_state->bus_format == MEDIA_BUS_FMT_FIXED) {
> > +
> > +		dev_err(ddev->dev, "Bridge connected to the encoder did not specify media bus format\n");
> >  		return -EINVAL;
> >  	}
> >  
> > -	// XXX any cleaner way to set bus format and flags?
> > -	tcrtc_state->bus_format = di->bus_formats[0];
> > -	if (!bus_flags_set)
> > -		tcrtc_state->bus_flags = di->bus_flags;
> > -
> >  	return 0;
> >  }
> >  
> 
> -- 
> Regards,
> 
> Laurent Pinchart
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