Re: [PATCH v3 2/4] arm64: dts: qcom: sc7180: revert "arm64: dts: qcom: sc7180: Avoid glitching SPI CS at bootup on trogdor"

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 19/10/2022 11:48, Doug Anderson wrote:
> Hi,
> 
> On Tue, Oct 18, 2022 at 5:14 PM Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>>
>> This reverts commit e440e30e26dd6b0424002ad0ddcbbcea783efd85 because it
>> is not a reliable way of fixing SPI CS glitch and it depends on specific
>> Linux kernel pin controller driver behavior.
>>
>> This behavior of kernel driver was changed in commit b991f8c3622c
>> ("pinctrl: core: Handling pinmux and pinconf separately") thus
>> effectively the DTS fix stopped being effective.
>>
>> Proper solution for the glitching SPI chip select must be implemented in
>> the drivers, not via ordering of entries in DTS.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>
>> ---
>>
>> Changes since v2:
>> 1. New patch
>>
>> Not tested on hardware.
>>
>> Cc: Doug Anderson <dianders@chromium.org>
>> ---
>>  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 27 +++-----------------
>>  1 file changed, 3 insertions(+), 24 deletions(-)
> 
> It would have been nice for the commit message to mention the fix in
> the driver, which has already landed as commit d21f4b7ffc22 ("pinctrl:
> qcom: Avoid glitching lines when we first mux to output").

I'll add it.

> 
> In any case:
> 
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
> 
> I've confirmed that this patch is fine after taking the pinctrl fix.
> 
> Tested-by: Douglas Anderson <dianders@chromium.org>

Awesome!

Best regards,
Krzysztof