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From: Ben Wolsieffer <ben.wolsieffer@hefring.com>
To: Mark Brown <broonie@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Ben Whitten <ben.whitten@gmail.com>
Subject: Re: [PATCH] regmap: prevent noinc writes from clobbering cache
Date: Wed, 1 Nov 2023 16:20:08 -0400	[thread overview]
Message-ID: <ZUKy-ETSbM7yNvNK@dell-precision-5540> (raw)
In-Reply-To: <b0e8c9f5-7aff-4adc-b5bc-d61c6107c07f@sirena.org.uk>

Hi Mark,

On Wed, Nov 01, 2023 at 05:05:39PM +0000, Mark Brown wrote:
> On Wed, Nov 01, 2023 at 10:29:27AM -0400, Ben Wolsieffer wrote:
> > Currently, noinc writes are cached as if they were standard incrementing
> > writes, overwriting unrelated register values in the cache. Instead, we
> > want to cache the last value written to the register, as is done in the
> > accelerated noinc handler (regmap_noinc_readwrite).
> 
> Could you please add a kunit test for this?

I started to look into this, but it is not currently possible to test
noinc behavior with regmap_[raw_]ram. The same bulk write operation is
used by both incrementing and non-incrementing writes, and the difference
in behavior is due to how the hardware handles the bulk write to a
particular register.

To test this behavior, regmap_raw_ram (raw because it supports bulk
writes) would have to be told that certain of its registers should
implement noinc semantics.

Is this something I should implement?

Thanks, Ben

  reply	other threads:[~2023-11-01 20:20 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-01 14:29 [PATCH] regmap: prevent noinc writes from clobbering cache Ben Wolsieffer
2023-11-01 17:05 ` Mark Brown
2023-11-01 20:20   ` Ben Wolsieffer [this message]
2023-11-01 20:24     ` Mark Brown
2023-11-01 18:06 ` Greg Kroah-Hartman
2023-11-02 11:52 ` Mark Brown

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