linux-kernel - Re: [PATCH v5 02/18] platform/x86: intel_scu_ipc: Log more information if SCU IPC command fails

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Date:   Wed, 12 Feb 2020 13:36:49 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Darren Hart <dvhart@...radead.org>,
        Lee Jones <lee.jones@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Zha Qipeng <qipeng.zha@...el.com>,
        "David E . Box" <david.e.box@...ux.intel.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 02/18] platform/x86: intel_scu_ipc: Log more
 information if SCU IPC command fails

On Tue, Feb 11, 2020 at 05:41:38PM +0200, Andy Shevchenko wrote:
> On Tue, Feb 11, 2020 at 04:25:47PM +0300, Mika Westerberg wrote:
> > Currently we only log an error if the command times out which makes it
> > hard to figure out the failing command. This changes the driver to log
> > command and subcommand with the error code which should make debugging
> > easier. This also allows us to simplify the callers as they don't need
> > to log these errors themselves.
> > 
> 
> Thanks, my comments below.
> 
> ...
> 
> >  	scu = ipcdev;
> > -	ipc_command(scu, sub << 12 | cmd);
> > +	cmdval = sub << 12 | cmd;
> > +	ipc_command(scu, cmdval);
> >  	err = intel_scu_ipc_check_status(scu);
> 
> > +	if (err)
> > +		dev_err(&scu->dev, "IPC command %#x failed with %d\n", cmdval,
> > +			err);
> 
> We may move it out of the mutex, right? Also, please keep it one line.

Yup.

> >  	mutex_unlock(&ipclock);
> >  	return err;
> 
> ...
> 
> >  	mutex_lock(&ipclock);
> 
> > +	cmdval = (inlen << 16) | (sub << 12) | cmd;
> > +	ipc_command(scu, cmdval);
> >  	err = intel_scu_ipc_check_status(scu);
> > -
> > -	if (!err) {
> > +	if (err) {
> > +		dev_err(&scu->dev, "IPC command %#x failed with %d\n", cmdval,
> > +			err);
> > +	} else {
> >  		for (i = 0; i < outlen; i++)
> >  			*out++ = ipc_data_readl(scu, 4 * i);
> >  	}
> 
> It's not visible in this context but it looks like above applies here as well.

You mean move outside of the lock? This one calls ipc_data_readl()
which should be under the lock.