linux-kernel - Re: [PATCHv2 2/2] PCAP regulator driver (for 2.6.32)

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Date:	Fri, 26 Jun 2009 23:14:43 -0300
From:	Daniel Ribeiro <drwyrm@...il.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Liam Girdwood <lrg@...mlogic.co.uk>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Eric Miao <eric.y.miao@...il.com>,
	David Brownell <david-b@...bell.net>,
	Pierre Ossman <pierre@...man.eu>,
	openezx-devel <openezx-devel@...ts.openezx.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.arm.linux.org.uk>
Subject: Re: [PATCHv2 2/2] PCAP regulator driver (for 2.6.32)

Em Sáb, 2009-06-27 às 02:04 +0100, Mark Brown escreveu:
> > +	if (vreg->n_voltages == 1)
> > +		return -EINVAL;
> 
> It'd be a little more friendly to check if the supported voltage is in
> the requested range.  However, that'd only be an issue if constraints
> allowed voltage changes which is obviously broken so a comment to that
> effect would be enough.  I wouldn't have mentioned it but...

Ok, I will add a comment.

> > +	ezx_pcap_read(pcap, vreg->reg, &tmp);
> > +	tmp |= (1 << vreg->en);
> > +	ezx_pcap_write(pcap, vreg->reg, tmp);
> 
> This read/modify/write cycle is racy; the individual regulator is locked
> by the core but this register is shared between all regulators on the
> chip so if two are being updated at once things will go wrong.  Most of
> the MFDs have a set_bits() function that does an atomic read/modify/write
> cycle for cases like this.

Good point, thanks! :)

-- 
Daniel Ribeiro

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