From: Carlo Caione <carlo@caione.org>
To: Mark Brown <broonie@kernel.org>
Cc: Kamlesh Gurudasani <kamlesh.gurudasani@gmail.com>,
Neil Armstrong <neil.armstrong@linaro.org>,
Jerome Brunet <jbrunet@baylibre.com>,
David Airlie <airlied@gmail.com>,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
Kevin Hilman <khilman@baylibre.com>,
Daniel Vetter <daniel@ffwll.ch>,
linux-arm-kernel@lists.infradead.org,
linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-spi@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 2/3] drm/tiny: ili9486: Do not assume 8-bit only SPI controllers
Date: Fri, 18 Nov 2022 20:02:32 +0100 [thread overview]
Message-ID: <8a3bdd84-2789-1b42-976f-2843320750b6@baylibre.com> (raw)
In-Reply-To: <Y3eoYTZRyRJnze1z@sirena.org.uk>
On 18/11/2022 16:44, Mark Brown wrote:
>> The problem arrives when your controller does support 16-bits, so
>> your data is not swapped, but you still put the data on the bus
>> with 8-bit transfers.
>
> Why would you need to use 8 bit transfers if the controller supports
> 16 bits?
No idea why this driver is forcing 8-bit transfers when the controller
supports 16-bits (this is what this patch is fixing).
My theory is that this driver was written with the Raspberry Pi HATs in
mind and (AFAICT) the RPi has an 8-bit only SPI controller so the driver
author didn't bother with anything different.
--
Carlo Caione
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next prev parent reply other threads:[~2022-11-18 19:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-17 8:47 [PATCH 0/3] Fix SPICC and ILI9486 drivers Carlo Caione
2022-11-17 8:47 ` [PATCH 1/3] drm/tiny: rpi-lcd-35: Enable driver module autoloading Carlo Caione
2022-11-17 8:47 ` [PATCH 2/3] drm/tiny: ili9486: Do not assume 8-bit only SPI controllers Carlo Caione
2022-11-17 11:09 ` Mark Brown
2022-11-17 13:40 ` Carlo Caione
2022-11-17 14:59 ` Mark Brown
2022-11-18 10:36 ` Carlo Caione
2022-11-18 15:44 ` Mark Brown
2022-11-18 19:02 ` Carlo Caione [this message]
2022-11-17 8:47 ` [PATCH 3/3] spi: meson-spicc: Lower CS between bursts Carlo Caione
2022-11-17 8:54 ` Neil Armstrong
2022-11-17 14:05 ` Carlo Caione
2022-11-17 10:59 ` Mark Brown
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