linux-kernel - Re: [PATCH 1/4] interconnect: qcom: Support bcm-voter-specific TCS wait behavior

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Message-ID: <fee03dda-4c17-701b-bb1a-bf9482cc476d@linaro.org>
Date:   Thu, 2 Jul 2020 12:02:23 +0300
From:   Georgi Djakov <georgi.djakov@...aro.org>
To:     Mike Tipton <mdtipton@...eaurora.org>
Cc:     bjorn.andersson@...aro.org, agross@...nel.org,
        linux-pm@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] interconnect: qcom: Support bcm-voter-specific TCS
 wait behavior

Hi Mike,

On 6/23/20 07:08, Mike Tipton wrote:
> Currently, all bcm-voters set tcs_cmd::wait=true for the last VCD
> command in each TCS (AMC, WAKE, and SLEEP). However, some bcm-voters
> don't need the completion and instead need to optimize for latency. For
> instance, disabling wait-for-completion in the WAKE set can decrease
> resume latency and allow for certain operations to occur in parallel
> with the WAKE TCS triggering. This is only safe in very specific
> situations. Keep the default behavior of always waiting, but allow it to
> be overridden in devicetree.
> 
> Signed-off-by: Mike Tipton <mdtipton@...eaurora.org>
> ---
>  drivers/interconnect/qcom/bcm-voter.c | 32 ++++++++++++++++++---------
>  1 file changed, 21 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/bcm-voter.c b/drivers/interconnect/qcom/bcm-voter.c
[..]
> @@ -336,7 +342,11 @@ static int qcom_icc_bcm_voter_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	voter->dev = &pdev->dev;
> -	voter->np = pdev->dev.of_node;
> +	voter->np = np;
> +
> +	if (of_property_read_u32(np, "qcom,tcs-wait", &voter->tcs_wait))

This DT property needs to be documented.

Thanks,
Georgi