Re: [PATCH 1/4] ARM: dts: imx6dl-alti6p: Fix the SPI chipselect polarity
From: Shawn Guo <shawnguo@kernel.org>
Date: 2021-09-22 03:06:45
On Fri, Jul 16, 2021 at 10:36:56AM -0300, Fabio Estevam wrote:
The conversion of the spi-imx driver to use GPIO descriptors
in commit 8cdcd8aeee28 ("spi: imx/fsl-lpspi: Convert to GPIO descriptors")
helped to detect the following SPI chipselect polarity mismatch on an
imx6q-sabresd for example:
[ 4.854337] m25p80@0 enforce active low on chipselect handle
Prior to the above commit, the chipselect polarity passed via cs-gpios
property was ignored and considered active-low.
The reason for such mismatch is clearly explained in the comments inside
drivers/gpio/gpiolib-of.c:
* SPI children have active low chip selects
* by default. This can be specified negatively
* by just omitting "spi-cs-high" in the
* device node, or actively by tagging on
* GPIO_ACTIVE_LOW as flag in the device
* tree. If the line is simultaneously
* tagged as active low in the device tree
* and has the "spi-cs-high" set, we get a
* conflict and the "spi-cs-high" flag will
* take precedence.
To properly represent the SPI chipselect polarity, change it to active-low
when the "spi-cs-high" property is absent.
Signed-off-by: Fabio Estevam <festevam@gmail.com>Applied all, thanks! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel