[alsa-devel] [PATCH 1/7] [RFC] OMAP: MCBSP: hwmod database for 2xxx devices
peter.ujfalusi at nokia.com
Fri Oct 15 09:13:49 CEST 2010
On Thursday 14 October 2010 17:51:15 ext Varadarajan, Charulatha wrote:
> > Yes, this need to be fixed, but it can be done later, it does
> > not need to be
> > part of the hwmod series.
This problem there for a long time, and so far no one complained, or fixed it.
Probably there are no users for pollread/write at all, but I would not remove
the functionality. It is better to fix them later.
> > > 2. DMA transfers would also not work as it requires a patch
> > similar to [y].
> > Well, this patch was sent in 2008. nowdays we moved the OMAP
> > audio support to
> > ASoC, and there are no 'legacy' ALSA arm/omap drivers anymore.
> > In ASoC the cpu_dai and the platform drivers are separate things.
> > This allows us to use the same platform driver (omap-pcm) for
> > McBSp, McPDM (and
> > in theory we could have OMAP2 EAC) cpu_dai drivers without
> > duplicating code.
> > As a note: most of the features this patch was trying to
> > implement is already
> > done for the ASoC implementation, but if there is need for
> > new features, it has
> > to be done using the ASoC framework.
> If we do this, would it not contradict the idea of keeping the door
> open for others to use the McBSP ports?
Why? If you add support for different sample formats to ASoC, it will not change
> If other users should be allowed to use McBSP ports, it is good to
> have DMA support in plat-omap/mcbsp.c itself and modify the asoc
> implementation to take advantage of the proposed new mcbsp
> design. If agreed, this shall be addressed later. Please let
> me know your thoughts on this.
What I mean is that later we could add DMA transfer functionality if there is a
need, but at the moment I don't see any reason to do that.
Also moving the DMA functionality to plat-omap/mcbsp.c would require quite a big
change in there, and as well in the ASoC code. On top of that we will broke the
sound/soc/omap/omap-pcm.c to be McBSP independent, and that is one of the main
points here. We are using omap-pcm.c with McBSP and McPDM dai drivers. That has
to remain the same.
In the future we can implement DMA transfer capabilities to mcbsp.
I would not do this as part of hwmod either.
I think such an extension to the current McBSP code is only needed if/when we
have other users for McBSP than audio.
> > > Coming back to the original question. Either we need to fix
> > the broken
> > > legacy mcbsp driver or move the omap-mcbsp driver completely to asoc
> > > layer. What do you say?
> > I would keep the partitioning same as it is now.
> > If there is a reason we can add bus driver functionality to
> > McBSP,
> Can you elaborate? mcbsp driver is already following platform bus
> device model.
I meant adding DMA functionality to McBSP. I would not worry about this at this
> > but at the
> > moment there is no need for that.
> For testing any changes in mcbsp driver (including hwmod), we are
> relying on internal patches (dma/pollmode patches). Instead, if
> mcbsp dma support is available in the driver itself, it would be
> useful for bug fixing/development activities.
You should use audio (ASoC) for verification, for example Beagle, or other
board. I would say that the audio support is solid on OMAP platforms, and that
is the main thing which must work after hwmod conversion.
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