linux-kernel - Re: [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right

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Message-ID: <CAD=FV=ULboyqRb1-1o1dq9Z7FGQ2gwb3oJi2bWLwZsXu6cybpw@mail.gmail.com>
Date:   Mon, 29 Jun 2020 16:45:30 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Dilip Kota <dkota@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-spi <linux-spi@...r.kernel.org>
Subject: Re: [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right

Hi,

On Mon, Jun 29, 2020 at 4:53 AM Mark Brown <broonie@...nel.org> wrote:
>
> On Fri, Jun 26, 2020 at 03:19:50PM -0700, Douglas Anderson wrote:
> > Setting the chip select on the Qualcomm geni SPI controller isn't
> > exactly cheap.  Let's cache the current setting and avoid setting the
> > chip select if it's already right.
>
> Seems like it'd be worth pushing this up to the core - if we're
> constantly setting the same CS value then perhaps we ought to just stop
> doing that?

Posted:

spi: Avoid setting the chip select if we don't need to
https://lore.kernel.org/r/20200629164103.1.Ied8e8ad8bbb2df7f947e3bc5ea1c315e041785a2@changeid

I see that you applied my patch to "spi-geni-qcom".  If the patch to
the core looks OK to you and lands, I think the one for the driver can
be reverted (though it doesn't hurt).

-Doug