linux-kernel - Re: [PATCH 3/3] soundwire: bus: clear parity interrupt before the mask is enabled

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Date:   Tue, 2 Feb 2021 10:14:00 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     Bard Liao <yung-chuan.liao@...ux.intel.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, rander.wang@...ux.intel.com,
        ranjani.sridharan@...ux.intel.com, hui.wang@...onical.com,
        sanyog.r.kale@...el.com, bard.liao@...el.com
Subject: Re: [PATCH 3/3] soundwire: bus: clear parity interrupt before the
 mask is enabled

On 01-02-21, 10:29, Pierre-Louis Bossart wrote:
> 
> > >   	 * Set SCP_INT1_MASK register, typically bus clash and
> > > diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
> > > index f7ba1a77a1df..c1fdc85d0a74 100644
> > > --- a/drivers/soundwire/intel.c
> > > +++ b/drivers/soundwire/intel.c
> > > @@ -1286,7 +1286,8 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
> > >   	if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
> > >   		prop->hw_disabled = true;
> > > -	prop->quirks = SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH;
> > > +	prop->quirks = SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH |
> > > +		SDW_MASTER_QUIRKS_CLEAR_INITIAL_PARITY;
> > 
> > move this to intel patch please..
> > 
> > >   	return 0;
> > >   }
> > > diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
> > > index a2766c3b603d..30415354d419 100644
> > > --- a/include/linux/soundwire/sdw.h
> > > +++ b/include/linux/soundwire/sdw.h
> > > @@ -426,6 +426,7 @@ struct sdw_master_prop {
> > >   };
> > >   #define SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH	BIT(0)
> > > +#define SDW_MASTER_QUIRKS_CLEAR_INITIAL_PARITY	BIT(1)
> > 
> > Why not add this quirk in patch 1..?
> 
> There is an element of history here. We first found out about the bus clash
> on multiple devices and dealt with a specific bug number. Then we spend
> weeks on the parity issue on a new platform and ultimately showed we needed
> a similar work-around.
> 
> All these problems are not typical from a user perspective; they appear when
> loading/unloading modules in loops, at some point it seems some hardware
> devices don't always reset properly or there's something problematic in
> power delivery.
> 
> I don't think it's an issue if we refactor the code to add the quirks first,
> and add the intel.c patches later. We probably want 2 intel changes to keep
> the references to the bugs though and the detailed explanations.

Yes I would like to see that. Explanations are always welcome including
development/debug notes.. Changelogs are very important documentation for
kernel, so relevant details are always good to add.
> 
> > Also add comments about each quirk, hopefully it wont be a big table
> 
> Sounds fine.

-- 
~Vinod