| Message ID | 20210507140334.204865-1-maxime@cerno.tech (mailing list archive) |
|---|---|
| Headers | show |
| Series | drm/vc4: hdmi: Enable Channel Mapping, IEC958, HBR Passthrough using hdmi-codec | expand |
Hi, On Fri, May 07, 2021 at 04:03:23PM +0200, Maxime Ripard wrote: > Hi, > > hdmi-codec allows to have a lot of HDMI-audio related infrastructure in place, > it's missing a few controls to be able to provide HBR passthrough. This series > adds more infrastructure for the drivers, and leverages it in the vc4 HDMI > controller driver. > > One thing that felt a bit weird is that even though > https://www.kernel.org/doc/html/latest/sound/kernel-api/writing-an-alsa-driver.html#iec958-s-pdif > mentions that the iec958 mask control should be a mixer control and the > default control should be a PCM one, it feels a bit weird to have two different > control type for two controls so similar, and other drivers are pretty > inconsistent with this. Should we update the documentation? Any comments on this series? Thanks! Maxime
On Mon, 24 May 2021 15:39:04 +0200, Maxime Ripard wrote: > > Hi, > > On Fri, May 07, 2021 at 04:03:23PM +0200, Maxime Ripard wrote: > > Hi, > > > > hdmi-codec allows to have a lot of HDMI-audio related infrastructure in place, > > it's missing a few controls to be able to provide HBR passthrough. This series > > adds more infrastructure for the drivers, and leverages it in the vc4 HDMI > > controller driver. > > > > One thing that felt a bit weird is that even though > > https://www.kernel.org/doc/html/latest/sound/kernel-api/writing-an-alsa-driver.html#iec958-s-pdif > > mentions that the iec958 mask control should be a mixer control and the > > default control should be a PCM one, it feels a bit weird to have two different > > control type for two controls so similar, and other drivers are pretty > > inconsistent with this. Should we update the documentation? > > Any comments on this series? A patch for updating the documentation is welcome. Currently, as de facto standard, we allow both MIXER and PCM ifaces for all IEC958-related controls, and it's unlikely that we would change that in future. thanks, Takashi
Hi Takashi, On Tue, May 25, 2021 at 10:35:14AM +0200, Takashi Iwai wrote: > On Mon, 24 May 2021 15:39:04 +0200, > Maxime Ripard wrote: > > > > Hi, > > > > On Fri, May 07, 2021 at 04:03:23PM +0200, Maxime Ripard wrote: > > > Hi, > > > > > > hdmi-codec allows to have a lot of HDMI-audio related infrastructure in place, > > > it's missing a few controls to be able to provide HBR passthrough. This series > > > adds more infrastructure for the drivers, and leverages it in the vc4 HDMI > > > controller driver. > > > > > > One thing that felt a bit weird is that even though > > > https://www.kernel.org/doc/html/latest/sound/kernel-api/writing-an-alsa-driver.html#iec958-s-pdif > > > mentions that the iec958 mask control should be a mixer control and the > > > default control should be a PCM one, it feels a bit weird to have two different > > > control type for two controls so similar, and other drivers are pretty > > > inconsistent with this. Should we update the documentation? > > > > Any comments on this series? > > A patch for updating the documentation is welcome. > Currently, as de facto standard, we allow both MIXER and PCM ifaces > for all IEC958-related controls, and it's unlikely that we would > change that in future. Ok, I'll write a patch for the documentation make it clearer then :) Do we want to make sure that all the iec958 controls are on the same iface, or is it also left to the driver (or should we just leave the existing drivers as is but encourage a consistent use in the future)? Maxime
On Tue, 25 May 2021 11:23:53 +0200, Maxime Ripard wrote: > > Hi Takashi, > > On Tue, May 25, 2021 at 10:35:14AM +0200, Takashi Iwai wrote: > > On Mon, 24 May 2021 15:39:04 +0200, > > Maxime Ripard wrote: > > > > > > Hi, > > > > > > On Fri, May 07, 2021 at 04:03:23PM +0200, Maxime Ripard wrote: > > > > Hi, > > > > > > > > hdmi-codec allows to have a lot of HDMI-audio related infrastructure in place, > > > > it's missing a few controls to be able to provide HBR passthrough. This series > > > > adds more infrastructure for the drivers, and leverages it in the vc4 HDMI > > > > controller driver. > > > > > > > > One thing that felt a bit weird is that even though > > > > https://www.kernel.org/doc/html/latest/sound/kernel-api/writing-an-alsa-driver.html#iec958-s-pdif > > > > mentions that the iec958 mask control should be a mixer control and the > > > > default control should be a PCM one, it feels a bit weird to have two different > > > > control type for two controls so similar, and other drivers are pretty > > > > inconsistent with this. Should we update the documentation? > > > > > > Any comments on this series? > > > > A patch for updating the documentation is welcome. > > Currently, as de facto standard, we allow both MIXER and PCM ifaces > > for all IEC958-related controls, and it's unlikely that we would > > change that in future. > > Ok, I'll write a patch for the documentation make it clearer then :) > > Do we want to make sure that all the iec958 controls are on the same > iface, or is it also left to the driver (or should we just leave the > existing drivers as is but encourage a consistent use in the future)? I'd leave the existing drivers as-is. Changing the iface is basically an incompatible change, and although most of applications and alsa-lib should look at both ifaces, there can be any surprise by that change. thanks, Takashi