linux-kernel - Re: [PATCH v2 13/15] phy: qcom-qmp-pcie: add support for pipediv2 clock

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Date:   Thu, 20 Oct 2022 11:31:35 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Johan Hovold <johan+linaro@...nel.org>,
        Vinod Koul <vkoul@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 13/15] phy: qcom-qmp-pcie: add support for pipediv2
 clock

On 19/10/2022 14:35, Johan Hovold wrote:
> Some QMP PHYs have a second fixed-divider pipe clock that needs to be
> enabled along with the pipe clock.
> 
> Add support for an optional "pipediv2" clock.
> 
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> ---
>   drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 42 ++++++++++++++++++++----
>   1 file changed, 36 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> index 9c8e009033f1..c1d74c06fad1 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> @@ -1379,7 +1379,9 @@ struct qmp_pcie {
>   	void __iomem *rx2;
>   
>   	struct clk *pipe_clk;
> +	struct clk *pipediv2_clk;
>   	struct clk_bulk_data *clks;
> +
>   	struct reset_control_bulk_data *resets;
>   	struct regulator_bulk_data *vregs;
>   
> @@ -1902,6 +1904,36 @@ static int qmp_pcie_exit(struct phy *phy)
>   	return 0;
>   }
>   
> +static int pipe_clk_enable(struct qmp_pcie *qmp)
> +{
> +	int ret;
> +
> +	ret = clk_prepare_enable(qmp->pipe_clk);
> +	if (ret) {
> +		dev_err(qmp->dev, "failed to enable pipe clock: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(qmp->pipediv2_clk);
> +	if (ret) {
> +		dev_err(qmp->dev, "failed to enable pipediv2 clock: %d\n", ret);
> +		goto err_disable_pipe_clk;
> +	}
> +
> +	return 0;
> +
> +err_disable_pipe_clk:
> +	clk_disable_unprepare(qmp->pipe_clk);
> +
> +	return ret;
> +}
> +
> +static void pipe_clk_disable(struct qmp_pcie *qmp)
> +{
> +	clk_disable_unprepare(qmp->pipediv2_clk);
> +	clk_disable_unprepare(qmp->pipe_clk);
> +}
> +
>   static int qmp_pcie_power_on(struct phy *phy)
>   {
>   	struct qmp_pcie *qmp = phy_get_drvdata(phy);
> @@ -1923,11 +1955,9 @@ static int qmp_pcie_power_on(struct phy *phy)
>   	qmp_pcie_init_registers(qmp, &cfg->tables);
>   	qmp_pcie_init_registers(qmp, mode_tables);
>   
> -	ret = clk_prepare_enable(qmp->pipe_clk);
> -	if (ret) {
> -		dev_err(qmp->dev, "pipe_clk enable failed err=%d\n", ret);
> +	ret = pipe_clk_enable(qmp);
> +	if (ret)
>   		return ret;
> -	}
>   
>   	/* Pull PHY out of reset state */
>   	qphy_clrbits(pcs, cfg->regs[QPHY_SW_RESET], SW_RESET);
> @@ -1950,7 +1980,7 @@ static int qmp_pcie_power_on(struct phy *phy)
>   	return 0;
>   
>   err_disable_pipe_clk:
> -	clk_disable_unprepare(qmp->pipe_clk);
> +	pipe_clk_disable(qmp);
>   
>   	return ret;
>   }
> @@ -1960,7 +1990,7 @@ static int qmp_pcie_power_off(struct phy *phy)
>   	struct qmp_pcie *qmp = phy_get_drvdata(phy);
>   	const struct qmp_phy_cfg *cfg = qmp->cfg;
>   
> -	clk_disable_unprepare(qmp->pipe_clk);
> +	pipe_clk_disable(qmp);
>   
>   	/* PHY reset */
>   	qphy_setbits(qmp->pcs, cfg->regs[QPHY_SW_RESET], SW_RESET);

I still think that the attached patch is somewhat simpler. Diffstat 
supports that idea:

$ diffstat /tmp/pipe.diff
  phy-qcom-qmp-pcie.c |   26 ++++++++++++++++----------
  1 file changed, 16 insertions(+), 10 deletions(-)

Yes, I'm speaking this after having cleaned up several open-coded 
versions of clk_bulk_foo from the drm/msm code. It typically starts with 
the 'just another clock' story, and then suddenly they are all over the 
code.

-- 
With best wishes
Dmitry

View attachment "pipe.diff" of type "text/x-patch" (2510 bytes)