[Letux-kernel] [PATCH v2] DTS: ARM: gta04: introduce legacy spi-cs-high to make display work again

Tony Lindgren tony at atomide.com
Mon Sep 23 19:34:41 CEST 2019


* H. Nikolaus Schaller <hns at goldelico.com> [190920 09:12]:
> 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.
> 
> This was not a problem until gpiolib changed the interpretation of
> GPIO_ACTIVE_HIGH and missing spi-cs-high.
> 
> 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 activate CS.

Thanks applying into fixes.

Tony


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