linux-kernel - [RFC PATCH 0/2] gpio: regmap: Ensure writes for aliased data values

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Message-ID: <20251020115636.55417-1-sander@svanheule.net>
Date: Mon, 20 Oct 2025 13:56:34 +0200
From: Sander Vanheule <sander@...nheule.net>
To: Michael Walle <mwalle@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	linux-gpio@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Sander Vanheule <sander@...nheule.net>
Subject: [RFC PATCH 0/2] gpio: regmap: Ensure writes for aliased data values

These patches aim to fix an issue with aliased data registers, where the
input values are read from an offset and the output values are written
to the same offset. The current use of regmap_update_bits() may cause an
input value to be used to decide not to write a new output value.

The first patch in this RFC aims to fix the above issue. The second
patch is optional, but allows to recover some performance by leveraging
the regmap cache.

I am currently revisiting an older patch series of mine [1]. I am
submitting these as an RFC to see if they are acceptable, but would
include the patch(es) in the respin of the series.

[1] https://lore.kernel.org/linux-gpio/cover.1623532208.git.sander@svanheule.net/

Sander Vanheule (2):
  gpio: regmap: Force writes for aliased data regs
  gpio: regmap: Bypass cache for aliased outputs

 drivers/gpio/gpio-regmap.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

-- 
2.51.0