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@xxxxxxxxxxxxxxx > Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> > --- > Documentation/devicetree/bindings/spi/spi-bus.txt | 6 ++++++ > arch/arm/boot/dts/omap3-gta04.dtsi | 1 + > 2 files changed, 7 insertions(+)
