linux-kernel - Re: [RFC PATCH 1/2] soundwire: add support for static port mapping

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20210201102709.GT2771@vkoul-mobl>
Date:   Mon, 1 Feb 2021 15:57:09 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        yung-chuan.liao@...ux.intel.com, gregkh@...uxfoundation.org,
        sanyog.r.kale@...el.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/2] soundwire: add support for static port mapping

On 25-01-21, 16:23, Srinivas Kandagatla wrote:
> 
> 
> On 22/01/2021 16:42, Pierre-Louis Bossart wrote:
> > > > 
> > > > if you completely remove the stream and re-add it with updated
> > > > configuration things should work.
> > > 
> > > That's exactly what we do currently!
> > > 
> > > The updated ports due to new configuration ex: for "mic capture"
> > > dailink needs to be communicated from slave(codec) to master so that
> > > it can allocate correct ports. That is what this patch is trying to
> > > do (share current port map information).
> > 
> > .. we have a disconnect on how to do this configuration update.
> > 
> > The 'stream' support was designed so that a stream can be split across
> > multiple devices (both masters and slaves). With this design we need to
> > have a central configuration and distribute the information to all
> > devices taking part of the stream.

That is correct, but in this case a stream consists of one master and
one or more slave devices. This is not a multi-master design. The adding
of multiple masters should not be done here... that does not seem
logically right in this situation

> > It seems you are in a different solution-space, where the codec driver
> > needs to notify the master of which ports it needs to use?
> 
> Correct! As Codec is the place where we have mixer controls ant it can
> clearly tell which master ports should be used for that particular
> configuration.

And that should come from firmware (DT etc) and driver should pass on
this info

> > I also don't see where the mapping is actually set. Patch 2 uses a
> > mapping but there's no codec driver change that defines the mapping?
> > 
> > Do you actually call sdw_stream_add_slave() with a new mapping?
> > 
> Yes, currently am working on a codec driver for WCD938x Codec, which I will
> posting very soon!
> 
> > It feels we are missing the codec part to really see what you are trying
> > to do?
> My WIP code is at https://git.linaro.org/people/srinivas.kandagatla/linux.git/tree/sound/soc/codecs/wcd938x.c?h=wcd938x/wip#n4526
> 
> Currently the master ports are hardcoded in the driver for now, but these
> will come from DT.
> 
> --srini

-- 
~Vinod