Am 20.09.2019 um 10:55 schrieb Linus Walleij linus.walleij@linaro.org:
On Tue, Sep 17, 2019 at 4:26 PM H. Nikolaus Schaller hns@goldelico.com wrote:
Am 17.09.2019 um 00:52 schrieb Linus Walleij linus.walleij@linaro.org: On Mon, Sep 16, 2019 at 12:59 PM H. Nikolaus Schaller hns@goldelico.com wrote:
ping.
Device omap3-gta04 is neither working with v5.3 nor linux-next quite a while and we need a solution.
Can't we just apply the last part of the patch in this thread:
diff --git a/arch/arm/boot/dts/omap3-gta04.dtsi b/arch/arm/boot/dts/omap3-gta04.dtsi index 9a9a29fe88ec..47bab8e1040e 100644 --- a/arch/arm/boot/dts/omap3-gta04.dtsi +++ b/arch/arm/boot/dts/omap3-gta04.dtsi @@ -124,6 +124,7 @@ spi-max-frequency = <100000>; spi-cpol; spi-cpha;
spi-cs-high; backlight= <&backlight>; label = "lcd";Surely this fixes the problem?
yes, it is a workaround, but appears to violate some policies. E.g. the spi-cs-high; is undocumented but DT bindings maintainer seems to be against documenting it as I had proposed in my other patch.
It is documented as a boolean in Documentation/devicetree/bindings/spi/spi-controller.yaml with the following description:
spi-cs-high: $ref: /schemas/types.yaml#/definitions/flag description: The device requires the chip select active high.So I don't think it is about it being undocumented.
Yes, the basic property is documented. But incomplete.
The strange inversion side-effect on the third gpio parameter is undocumented and not understandable from this description alone.
Rather he seems to have proposed a white-list in the driver code. So that the legacy mode is only becoming active for those systems which really need the legacy mode instead of everyone.
Yeah that seems like a plausible way forward if we want to move away from the legacy way of specifying polarity.
Then, we do not need this patch for GTA04.
We don't need to implement the perfect solution up front. We can aim for that in the long run. I usually go by the IETF motto "rough consensus and running code".
So its up to you to decide which way to go. We are happy with any one that makes mainline work again asap...
I suggest to go both way: apply this oneliner and tag for stable so that GTA04 works again.
Then for the next kernel think about a possible more abitious whitelist solution and after adding that remove *all* "spi-cs-high" flags from all device trees in the kernel after fixing them all up.
Ok, that looks like a viable path.
BR and thanks, Nikolaus