linux-kernel - Re: [alsa-devel] [RFC PATCH] ASoC: Modify check condition of multiple bindings of components

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Message-ID: <1444962713.31246.6.camel@mtksdaap41>
Date:	Fri, 16 Oct 2015 10:31:53 +0800
From:	Koro Chen <koro.chen@...iatek.com>
To:	Lars-Peter Clausen <lars@...afoo.de>
CC:	Mark Brown <broonie@...nel.org>, <alsa-devel@...a-project.org>,
	<srv_heupstream@...iatek.com>, <tiwai@...e.de>,
	<s.hauer@...gutronix.de>, <linux-kernel@...r.kernel.org>,
	<lgirdwood@...il.com>, <linux-mediatek@...ts.infradead.org>,
	<p.zabel@...gutronix.de>, <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [alsa-devel] [RFC PATCH] ASoC: Modify check condition of
 multiple bindings of components

On Thu, 2015-10-15 at 15:26 +0200, Lars-Peter Clausen wrote:
> On 10/15/2015 02:10 PM, Mark Brown wrote:
> > On Wed, Oct 14, 2015 at 11:00:01AM +0200, Lars-Peter Clausen wrote:
> > 
> >> It was never intended that it is possible to bind a component to multiple
> >> cards. That it was possible was a bug that was overlooked and some people
> >> tried to do it which caused apparently random crashes later on, caused by
> >> the data structure corruption. This is why we added the check to catch this
> >> kind of mistake early and to avoid the crashes.
> > 
> > This is true, but I do think it's something that we should have some
> > story on supporting for some of this hardware that has a bunch of
> > channels in one IP block that can't really interact with each other.
> > It's going to make it a lot easier for people to think about the
> > hardware and how to describe it.
> 
> I'm not saying we shouldn't support it, just that we can't support it with
> the current code. And adding support for it will require a fair bit of
> restructuring.
> 
> If a hardware block as multiple independent channels the best approach in my
> opinion is to register multiple components (Which we can't do at the moment,
> because there can only be one component per device). From a framework point
Yes... I have tried to register 2 platforms in my ASoC platform driver
but alsa considered they are the same platform since they are from the
same device.
> of view there is no difference between a single device with multiple
> independent channels and multiple independent devices with one channel each.
> Both have the same logical topology.
> 
Yes, but in my case there is only one HW, one set of registers, and one
set of clocks, it should be a single device node in the device tree. 
> - Lars
> 
> 


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