Re: [PATCH v6 3/8] drm/bridge: mhdp8546: Add minimal format negotiation

From: Tomi Valkeinen
Date: Mon May 29 2023 - 07:12:37 EST

On 29/05/2023 08:37, Aradhya Bhatia wrote:
Btw, we seem to be missing get-output-fmt from the mdhp driver.
Yes, we are.

With the drm_bridge_attach call added, the display-connector bridge will
assign MEDIA_BUS_FMT_FIXED as the default output format. And most
bridges support only their primary output bus format in their
get-output-fmt hooks. I suppose it would be RGB121212_1X36 in mhdp8546's

Do we require this when there is no comprehensive way to determine if
another bus format may be more suitable (depending on the hardware

If I recall right, mhdp supports other formats than RGB121212_1X36 on the input side (different bit depths and also yuv). On the output side, even if the input is 12 bits per component, when connected to a normal monitor, the output bpc would be 8.

I'm not sure if any of that matters, as nobody (?) will use the output format of mhdp, as it just goes "outside" to the monitor, and it is the mhdp driver that negotiates a suitable output format with the monitor.