Groups > linux.kernel > #1542081

Re: [PATCH v2 2/2] mfd: axp20x: Fix AXP806 access errors on cold boot

From	Mark Brown <broonie@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/2] mfd: axp20x: Fix AXP806 access errors on cold boot
Date	2016-12-14 18:50 +0100
Message-ID	<sOlQJ-12U-5@gated-at.bofh.it> (permalink)
References	<sGwgh-7L8-3@gated-at.bofh.it> <sGwgh-7L8-1@gated-at.bofh.it> <sMrnz-2zR-11@gated-at.bofh.it> <sNYr7-3vi-7@gated-at.bofh.it> <sOig9-77w-17@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

On Wed, Dec 14, 2016 at 09:52:31PM +0800, Chen-Yu Tsai wrote:

> What this patch does is make sure the registers match, to guarantee
> access, and then reinitialize the regmap cache to get rid of any
> stale data.

So what you're saying is that previous writes may have been ignored?

> > If the chip has been reset then you'd want to reset the cache too.  I've
> > no idea if that's needed here or not though, it depends what happens to
> > the global state of the chip when this reconfiguration happens.

> It is not a reset in the general sense. I suppose a better way would
> be to do an explicit write to the register first, then initialize
> the regmap. I'd have to export the write function from the RSB bus
> driver first though.

Surely just doing a write immediately after initializing the regmap
would have the same effect?  That'd ensure that the hardware has the
desired value before there are any other writes.  But I might be missing
something here.

Thread

Re: [PATCH v2 2/2] mfd: axp20x: Fix AXP806 access errors on cold boot Mark Brown <broonie@kernel.org> - 2016-12-13 17:50 +0100
  Re: [PATCH v2 2/2] mfd: axp20x: Fix AXP806 access errors on cold boot Chen-Yu Tsai <wens@csie.org> - 2016-12-14 15:00 +0100
    Re: [PATCH v2 2/2] mfd: axp20x: Fix AXP806 access errors on cold boot Mark Brown <broonie@kernel.org> - 2016-12-14 18:50 +0100
      Re: [PATCH v2 2/2] mfd: axp20x: Fix AXP806 access errors on cold boot Chen-Yu Tsai <wens@csie.org> - 2017-01-03 05:00 +0100

csiph-web