linux-kernel - Re: [PATCH] clk: qcom: smd-rpm: conditionally enable scaling before doing handover

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Message-ID: <20bd79c1-6c38-f1ed-1661-6fa4c308c5c5@linaro.org>
Date:   Tue, 16 May 2023 03:27:46 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Luca Weiss <luca@...tu.xyz>, ~postmarketos/upstreaming@...ts.sr.ht,
        phone-devel@...r.kernel.org,
        Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: qcom: smd-rpm: conditionally enable scaling before
 doing handover



On 6.05.2023 22:10, Luca Weiss wrote:
> On older platforms like msm8226, msm8974 and msm8916 the driver in the
> downstream kernel enables scaling first before doing the handover of the
> clocks.
> 
> While this normally doesn't seem to cause noticeable problems, on
> apq8026-asus-sparrow this causes the device to immediately reboot,
> perhaps due to older rpm firmware that becomes unhappy.
> 
> On newer platforms the order has swapped and enabling scaling is done
> after the handover, so let's introduce this behavior only conditionally
> for msm8226 and msm8974 for now.
> 
> Signed-off-by: Luca Weiss <luca@...tu.xyz>
> ---
Did you give this a spin on some 8974? I think hammerhead had
issues around rpmcc in the past..

Konrad
>  drivers/clk/qcom/clk-smd-rpm.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/qcom/clk-smd-rpm.c b/drivers/clk/qcom/clk-smd-rpm.c
> index 887b945a6fb7..6d5476afc4d1 100644
> --- a/drivers/clk/qcom/clk-smd-rpm.c
> +++ b/drivers/clk/qcom/clk-smd-rpm.c
> @@ -178,6 +178,7 @@ struct clk_smd_rpm_req {
>  struct rpm_smd_clk_desc {
>  	struct clk_smd_rpm **clks;
>  	size_t num_clks;
> +	bool scaling_before_handover;
>  };
>  
>  static DEFINE_MUTEX(rpm_smd_clk_lock);
> @@ -693,6 +694,7 @@ static struct clk_smd_rpm *msm8974_clks[] = {
>  static const struct rpm_smd_clk_desc rpm_clk_msm8974 = {
>  	.clks = msm8974_clks,
>  	.num_clks = ARRAY_SIZE(msm8974_clks),
> +	.scaling_before_handover = true,
>  };
>  
>  static struct clk_smd_rpm *msm8976_clks[] = {
> @@ -1318,6 +1320,12 @@ static int rpm_smd_clk_probe(struct platform_device *pdev)
>  	rpm_smd_clks = desc->clks;
>  	num_clks = desc->num_clks;
>  
> +	if (desc->scaling_before_handover) {
> +		ret = clk_smd_rpm_enable_scaling(rpm);
> +		if (ret)
> +			goto err;
> +	}
> +
>  	for (i = 0; i < num_clks; i++) {
>  		if (!rpm_smd_clks[i])
>  			continue;
> @@ -1329,9 +1337,11 @@ static int rpm_smd_clk_probe(struct platform_device *pdev)
>  			goto err;
>  	}
>  
> -	ret = clk_smd_rpm_enable_scaling(rpm);
> -	if (ret)
> -		goto err;
> +	if (!desc->scaling_before_handover) {
> +		ret = clk_smd_rpm_enable_scaling(rpm);
> +		if (ret)
> +			goto err;
> +	}
>  
>  	for (i = 0; i < num_clks; i++) {
>  		if (!rpm_smd_clks[i])
> 
> ---
> base-commit: dd9e11d6477a52ede9ebe575c83285e79e823889
> change-id: 20230506-rpmcc-scaling-handover-a63029ed9d13
> 
> Best regards,