How does the media controller decide what type of display is attached?

_Ralph_

Can someone from TI tell me how the media controller decides what format of display is attached to it?

The specific thing I'm looking at is how to force the VPSS driver to use DVI out instead of HDMI out even when an HDMI-capable display is attached.

The decision making part of the Linux driver is in vpss/dctrl.c and all I see are some magic vps_fvid2_control calls to the media controller that then effectively says if the driver should output HDMI or DVI.

Thanks,

Ralph

over 13 years ago

0 HardikShah over 13 years ago

TI__Mastermind 20245 points

Hi,

HDMI or DVI mode to be set is controlled locally on A8. No decisions are taken on M3 since this is a job of HDMI driver and is local to A8. This is decided based on EDID. Driver reads EDID of sink. Based on EDID it sets either DVI or HDMI mode. Why you want to force it to DVI.

Regards,

Hardik Shah

0 _Ralph_ over 13 years ago in reply to HardikShah

Guru 10685 points

The DVI signal is simpler at the physical layer than HDMI so it is easier to scope.

Ralph

0 HardikShah over 13 years ago in reply to _Ralph_

TI__Mastermind 20245 points

Hi,

You want this for debugging your board. Then i can provied you a hack to configure HDMI in DVI mode by default. Please let me know your PSP release version number.

Regards,

Hardik Shah

0 _Ralph_ over 13 years ago in reply to HardikShah

Guru 10685 points

Hi Hardik,

Thanks for the offer. I've already implemented my own hack in "dctrl.c". :-)

Look forward to being able to set DVI/HDMI in sysfs...

Ralph

0 HardikShah over 13 years ago in reply to _Ralph_

TI__Mastermind 20245 points

0 Daniel70334 over 13 years ago in reply to HardikShah

Expert 1745 points

Hardik,

Regarding Ralph's comment: "Look forward to being able to set DVI/HDMI in sysfs..."

Can you confirm if there indeed will be a way to set DVI/HDMI mode from sysfs? Our product normally have a feature to force one mode or the other. Plus, long term, we probably want to bypass the EDID processing in vpss, and substitute our own. Having direct control of HDMI mode and output timing would help.

Dan -

Processors

Processors forum

How does the media controller decide what type of display is attached?