linux-kernel - Re: [PATCH 0/2] spi: spi-qcom-qspi: Avoid some per-transfer overhead

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Date:   Wed, 8 Jul 2020 14:09:42 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     Douglas Anderson <dianders@...omium.org>,
        Mark Brown <broonie@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     mka@...omium.org, Akash Asthana <akashast@...eaurora.org>,
        swboyd@...omium.org, linux-arm-msm@...r.kernel.org,
        georgi.djakov@...aro.org, ctheegal@...eaurora.org,
        mkshah@...eaurora.org, linux-kernel@...r.kernel.org,
        linux-spi@...r.kernel.org
Subject: Re: [PATCH 0/2] spi: spi-qcom-qspi: Avoid some per-transfer overhead


On 7/8/2020 1:46 AM, Douglas Anderson wrote:
> 
> Not to be confused with the similar series I posed for the _other_
> Qualcomm SPI controller (spi-geni-qcom) [1], this one avoids the
> overhead on the Quad SPI controller.
> 
> It's based atop the current Qualcomm tree including Rajendra's ("spi:
> spi-qcom-qspi: Use OPP API to set clk/perf state").  As discussed in
> individual patches, these could ideally land through the Qualcomm tree
> with Mark's Ack.
> 
> Measuring:
> * Before OPP / Interconnect patches reading all flash takes: ~3.4 seconds
> * After OPP / Interconnect patches reading all flash takes: ~4.7 seconds
> * After this patch reading all flash takes: ~3.3 seconds

Thanks Doug, I saw similar benefit on my setup with these patches. They do help
reduce the (unnecessary) additional overhead so it makes sense to merge these
along with the OPP/Interconnect patches in-order to avoid the regression.

Reviewed-by: Rajendra Nayak <rnayak@...eaurora.org>
Tested-by: Rajendra Nayak <rnayak@...eaurora.org>

> 
> [1] https://lore.kernel.org/r/20200702004509.2333554-1-dianders@chromium.org
> [2] https://lore.kernel.org/r/1593769293-6354-2-git-send-email-rnayak@codeaurora.org
> 
> 
> Douglas Anderson (2):
>    spi: spi-qcom-qspi: Avoid clock setting if not needed
>    spi: spi-qcom-qspi: Set an autosuspend delay of 250 ms
> 
>   drivers/spi/spi-qcom-qspi.c | 45 ++++++++++++++++++++++++++++---------
>   1 file changed, 35 insertions(+), 10 deletions(-)
> 

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