From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Ossman Subject: Re: radeon multi-channel lpcm Date: Thu, 6 Sep 2012 09:52:51 +0200 Message-ID: <20120906095251.65f81ffc@mjolnir.ossman.eu> References: <20120831223447.065fcb62@mjolnir.ossman.eu> <20120905181923.2e330a63@mjolnir.ossman.eu> <20120905192239.6a212683@mjolnir.ossman.eu> <20120906090900.63328552@mjolnir.ossman.eu> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6610112485246468878==" Return-path: Received: from smtp-relay.ossman.eu (saehrimnir.ossman.eu [193.12.253.10]) by alsa0.perex.cz (Postfix) with ESMTP id 54DBB265CAA for ; Thu, 6 Sep 2012 09:52:57 +0200 (CEST) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Takashi Iwai Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org This is a MIME-formatted message. If you see this text it means that your E-mail software does not support MIME-formatted messages. --===============6610112485246468878== Content-Type: multipart/signed; micalg=PGP-SHA256; protocol="application/pgp-signature"; boundary="=_freyr.ossman.eu-21391-1346917974-0001-2" This is a MIME-formatted message. If you see this text it means that your E-mail software does not support MIME-formatted messages. --=_freyr.ossman.eu-21391-1346917974-0001-2 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 06 Sep 2012 09:28:52 +0200 Takashi Iwai wrote: > At Thu, 6 Sep 2012 09:09:00 +0200, > Pierre Ossman wrote: > >=20 > > 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. >=20 > 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. >=20 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. > >=20 > > (2 is currently missing in the radeon driver, but it is trivial to add > > AFAICT) >=20 > Yeah, that's the big missing piece. >=20 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 --=20 -- Pierre Ossman WARNING: This correspondence is being monitored by FRA, a Swedish intelligence agency. Make sure your server uses encryption for SMTP traffic and consider using PGP for end-to-end encryption. --=_freyr.ossman.eu-21391-1346917974-0001-2 Content-Type: application/pgp-signature; name="signature.asc" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iF4EAREIAAYFAlBIVlUACgkQopDLsoqlmEI7mAEAip5fpN493q5vqJRF4Wq320qn HGxPt0miEF4zzSKzHB4A/j1tU3QHhOreYRCKjulM1LFmzQZlMzhC2pUd+daylYAx =pzQS -----END PGP SIGNATURE----- --=_freyr.ossman.eu-21391-1346917974-0001-2-- --===============6610112485246468878== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline --===============6610112485246468878==--