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

[Doug Anderson]

Hi,

On Tue, Oct 18, 2022 at 5:14 PM Krzysztof Kozlowski
<krzysztof.kozlowski@xxxxxxxxxx> 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@xxxxxxxxxx>
>
> ---
>
> Changes since v2:
> 1. New patch
>
> Not tested on hardware.
>
> Cc: Doug Anderson <dianders@xxxxxxxxxxxx>
> ---
>  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").

In any case:

Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>

I've confirmed that this patch is fine after taking the pinctrl fix.

Tested-by: Douglas Anderson <dianders@xxxxxxxxxxxx>