On Thu, 06 Sep 2012 09:28:52 +0200 Takashi Iwai tiwai@suse.de wrote:
At Thu, 6 Sep 2012 09:09:00 +0200, Pierre Ossman wrote:
But if you're saying that the hardware doesn't really need the ELD, then steps 3-4 could be replaced by a pure software channel.
No, what I meant is about the audio codec perspective. From the audio codec, it has no direct hardware access to GPU that actually handles the ELD register things. It always communicate via HD-audio verbs to send/receive DIP bytes so the actual work is purely in the graphics driver side.
I assume "codec" here is in the HDA sense, as in the hardware hiding somewhere behind the HDA interface.
In the Intel case, I'd say the audio hardware as a whole does have some back channel to the GPU since a write to a GPU register somehow results in data in the audio hardware. But yes, it would be a purely graphics driver thing as it has both the ELD, and access to the registers you can write to.
I'm working on the assumption that the radeon hardware works in similar fashion as the Intel ones.
This would be convenient as it is currently unknown how to do 3) on radeon.
(2 is currently missing in the radeon driver, but it is trivial to add AFAICT)
Yeah, that's the big missing piece.
So I'll go poke the AMD people, as I cannot find anything in the public docs about ELD registers. Hopefully it's not something that's still classified... :/
Thanks