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Subject: Re: [PATCH 1/3] spi: spi-geni-qcom: Avoid clock setting if not needed
To:     Douglas Anderson <dianders@chromium.org>,
        Mark Brown <broonie@kernel.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>
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        swboyd@chromium.org, georgi.djakov@linaro.org,
        ctheegal@codeaurora.org, mka@chromium.org,
        linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org
References: <20200702004509.2333554-1-dianders@chromium.org>
 <20200701174506.1.Icfdcee14649fc0a6c38e87477b28523d4e60bab3@changeid>
From:   Akash Asthana <akashast@codeaurora.org>
Message-ID: <1b9f0313-0e8f-0a75-b0a5-b6a768af0a7a@codeaurora.org>
Date:   Tue, 7 Jul 2020 15:46:22 +0530
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On 7/2/2020 6:15 AM, Douglas Anderson wrote:
> Every SPI transfer could have a different clock rate.  The
> spi-geni-qcom controller code to deal with this was never very well
> optimized and has always had a lot of code plus some calls into the
> clk framework which, at the very least, would grab a mutex.  However,
> until recently, the overhead wasn't _too_ much.  That changed with
> commit 0e3b8a81f5df ("spi: spi-geni-qcom: Add interconnect support")
> we're now calling geni_icc_set_bw(), which leads to a bunch of math
> plus:
>    geni_icc_set_bw()
>      icc_set_bw()
>        apply_constraints()
>          qcom_icc_set()
>            qcom_icc_bcm_voter_commit()
>              rpmh_invalidate()
>              rpmh_write_batch()
> ...and those rpmh commands can be a bit beefy if you call them too
> often.

Reviewed-by: Akash Asthana<akashast@codeaurora.org>

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