linux-kernel - Re: [PATCH v2] mfd: da9052-spi: change read-mask to write-mask

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Message-ID: <aN4oad5e7YUNaR8w@gmail.com>
Date: Thu, 2 Oct 2025 09:23:21 +0200
From: Marcus Folkesson <marcus.folkesson@...il.com>
To: Ian Ray <ian.ray@...ealthcare.com>
Cc: Support Opensource <support.opensource@...semi.com>,
	Lee Jones <lee@...nel.org>, Axel Lin <axel.lin@...ics.com>,
	Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mfd: da9052-spi: change read-mask to write-mask

Hello Ian,

On Wed, Oct 01, 2025 at 04:03:37PM +0300, Ian Ray wrote:
> Hello Marcus,
> 
> On Wed, Sep 25, 2024 at 12:19:53PM +0200, Marcus Folkesson wrote:
> > Driver has mixed up the R/W bit.
> > The LSB bit is set on write rather than read.
> > Change it to avoid nasty things to happen.
> > 
> > Fixes: e9e9d3973594 ("mfd: da9052: Avoid setting read_flag_mask for da9052-i2c driver")
> > Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
> 
> Your patch breaks DA9053 SPI communication (for me, at least) on the
> 6.1.y branch (I have not tested on master).
> 
> The datasheets [1] and [2] both refer to R/Wn in the SPI signalling.
> 
> What led to the assertion that "The LSB bit is set on write rather
> than read."?
> 
> In the original code "config.read_flag_mask = 1;", is OR'd into the
> buffer in regmap_set_work_buf_flag_mask.  This sets the "R" bit as
> expected.

Hrm.

I follow you and agree with what you say.
Could you please read out R19 INTERFACE register?
Bit 3, R/W POL, deviates from the default value (1) in my setup, which
is probably the reason why it doesn't work for me without the patch.

Your datasheet revision is later than mine, could you plese verify that
the default value is still 1 for DA9052 in your revision?

If that is the case, either the datasheet is wrong or my chips must
somehow been preloaded with some values.

As nobody else has reported any issue I guess it is safer to revert
this patch.

> 
> [1] DA9052 CFR0011-120-00 Rev 5, Revision 2.5, 13-Feb-2017, page 67.
> [2] DA9053 DA9053-00-IDS2n_131017, page 54.
> 
> Blue skies,
> Ian


Best regards,
Marcus Folkesson

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