On Mon, Jul 08, 2019 at 04:46:05PM +0200, H. Nikolaus Schaller wrote:
commit 6953c57ab172 "gpio: of: Handle SPI chipselect legacy bindings"
did introduce logic to centrally handle the legacy spi-cs-high property in combination with cs-gpios. This assumes that the polarity of the CS has to be inverted if spi-cs-high is missing, even and especially if non-legacy GPIO_ACTIVE_HIGH is specified.
The DTS for the GTA04 was orginally introduced under the assumption that there is no need for spi-cs-high if the gpio is defined with proper polarity GPIO_ACTIVE_HIGH.
Given that spi-cs-high is called legacy, that would imply that DT's should not have to use spi-cs-high.
This was not a problem until gpiolib changed the interpretation of GPIO_ACTIVE_HIGH and missing spi-cs-high.
Then we should fix gpiolib...
The effect is that the missing spi-cs-high is now interpreted as CS being low (despite GPIO_ACTIVE_HIGH) which turns off the SPI interface when the panel is to be programmed by the panel driver.
Therefore, we have to add the redundant and legacy spi-cs-high property to properly pass through the legacy handler.
Since this is nowhere documented in the bindings, we add some words of WARNING.
Cc: stable@vger.kernel.org Signed-off-by: H. Nikolaus Schaller hns@goldelico.com
Documentation/devicetree/bindings/spi/spi-bus.txt | 6 ++++++ arch/arm/boot/dts/omap3-gta04.dtsi | 1 + 2 files changed, 7 insertions(+)