[PATCH 2/5] drm/tidss: Set bus_format correctly from bridge/connector

[Nikhil Devshatwar]

On 00:57-20201030, Laurent Pinchart wrote:
> Hi Nikhil,
> 
> Thank you for the patch.
> 
> On Fri, Oct 16, 2020 at 04:09:14PM +0530, Nikhil Devshatwar wrote:
> > When there is a chain of bridges attached to the encoder,
> > the bus_format should be ideally set from the input format of the
> > first bridge in the chain.
> > 
> > Use the bridge state to get the negotiated bus_format.
> > If the bridge does not support format negotiation, error out
> > and fail.
> > 
> > Signed-off-by: Nikhil Devshatwar <nikhil.nd at ti.com>
> > ---
> >  drivers/gpu/drm/tidss/tidss_encoder.c | 16 +++++++++++-----
> >  1 file changed, 11 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/tidss/tidss_encoder.c b/drivers/gpu/drm/tidss/tidss_encoder.c
> > index e278a9c89476..ae7f134754b7 100644
> > --- a/drivers/gpu/drm/tidss/tidss_encoder.c
> > +++ b/drivers/gpu/drm/tidss/tidss_encoder.c
> > @@ -22,6 +22,7 @@ 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;
> >  
> > @@ -41,14 +42,19 @@ static int tidss_encoder_atomic_check(struct drm_encoder *encoder,
> >  		break;
> >  	}
> >  
> > -	if (!di->bus_formats || di->num_bus_formats == 0)  {
> > -		dev_err(ddev->dev, "%s: No bus_formats in connected display\n",
> > -			__func__);
> > +	/* Copy the bus_format from the input_bus_format of first bridge */
> > +	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;
> > +
> > +	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;
> 
> Shouldn't the flags also be retrieved from the bridge state ?

Yes, the code does that above, not covered in the diff context.
When no bridges have reported the timings,
it uses the display_info as fallback (when bus_flags_set is false)

Nikhil D

> 
> >  
> 
> -- 
> Regards,
> 
> Laurent Pinchart