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

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@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