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@xxxxxx>
> > ---
> > 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
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