Re: [PATCH] backlight: corgi: Fix gpio numbers for backlight controls

From: Lee Jones <lee.jones@linaro.org>
To: Laurence de Bruxelles <lfdebrux@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Robert Jarzmik <robert.jarzmik@free.fr>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] backlight: corgi: Fix gpio numbers for backlight controls
Date: Mon, 27 Jun 2022 08:43:33 +0100	[thread overview]
Message-ID: <YrlfpdrhPg08gySA@google.com> (raw)
In-Reply-To: <20220617212037.28118-1-lfdebrux@gmail.com>

On Fri, 17 Jun 2022, Laurence de Bruxelles wrote:

> With recent stable kernels on my Zaurus Akita I am unable to change the
> backlight brightness, as the necessary files are not in the sys
> filesystem, and at startup I get the following errors:
> 
> corgi-lcd spi2.1: requested GPIO 0 (207) is out of range [0..120] for
> chip gpio-pxa
> corgi-lcd: probe of spi2.1 failed with error -22
> 
> Looking at recent changes to the Corgi backlight driver, I found that
> commit ee0c8e494cc3 ("backlight: corgi: Convert to use GPIO
> descriptors") replaced the use of the deprecated integer-based GPIO
> interface, but didn't convert the GPIO numbers in the platform header
> to match this. I think this is what causes the error, as the GPIOs for
> the backlight are part of an expander chip with a GPIO base number
> larger than the number of GPIOs for the gpio-pxa device.
> 
> This patch fixes things by updating the GPIO numbers for the backlight,
> simply by dropping the GPIO base. It also updates the GPIO lookups to
> look in the table for the appropriate expander. For the Akita platform
> the expander with i2c address 0-0018 is used, for Spitz and Borzoi
> the second Sharp SCOOP expander is used.
> 
> I've tested this patch with real Akita and Spitz handhelds, as well as
> with QEMU.
> 
> Signed-off-by: Laurence de Bruxelles <lfdebrux@gmail.com>
> Fixes: ee0c8e494cc3 ("backlight: corgi: Convert to use GPIO descriptors")
> ---
>  arch/arm/mach-pxa/spitz.c |  8 ++++----
>  arch/arm/mach-pxa/spitz.h | 34 +++++++++++++++++-----------------
>  2 files changed, 21 insertions(+), 21 deletions(-)

Subject line should not be "backlight: ".

Try "ARM: pxa: " instead please.

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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