linux-kernel - Re: [PATCH 3/7] soundwire: intel: add mutex to prevent concurrent access to SHIM registers

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Date:   Mon, 23 Mar 2020 17:48:17 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
        jank@...ence.com, srinivas.kandagatla@...aro.org,
        slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Hui Wang <hui.wang@...onical.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [PATCH 3/7] soundwire: intel: add mutex to prevent concurrent
 access to SHIM registers

On 20-03-20, 09:07, Pierre-Louis Bossart wrote:
> 
> > > diff --git a/drivers/soundwire/intel.h b/drivers/soundwire/intel.h
> > > index 38b7c125fb10..568c84a80d79 100644
> > > --- a/drivers/soundwire/intel.h
> > > +++ b/drivers/soundwire/intel.h
> > > @@ -15,6 +15,7 @@
> > >    * @irq: Interrupt line
> > >    * @ops: Shim callback ops
> > >    * @dev: device implementing hw_params and free callbacks
> > > + * @shim_lock: mutex to handle access to shared SHIM registers
> > >    */
> > >   struct sdw_intel_link_res {
> > >   	struct platform_device *pdev;
> > > @@ -25,6 +26,7 @@ struct sdw_intel_link_res {
> > >   	int irq;
> > >   	const struct sdw_intel_ops *ops;
> > >   	struct device *dev;
> > > +	struct mutex *shim_lock; /* protect shared registers */
> > 
> > Where is this mutex initialized? Did you test this...
> 
> Dude, we've been testing the heck out of SoundWire.
> 
> If you want to see the actual initialization it's in the intel_init.c code:
> 
> https://github.com/thesofproject/linux/blob/9c7487b33072040ab755d32ca173b75151c0160c/drivers/soundwire/intel_init.c#L231

Which doesn't make much sense. A patch should do complete thing. I don't
see a reason why you cannot pull this single line into this patch.

It belongs here, not anywhere else.

-- 
~Vinod