linux-kernel - Re: [PATCH V6 6/6] scsi: ufs: qcom: Configure clk HW division based on scaling conditions.

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Message-ID: <20230901161351.GW818859@hu-bjorande-lv.qualcomm.com>
Date:   Fri, 1 Sep 2023 09:13:51 -0700
From:   Bjorn Andersson <quic_bjorande@...cinc.com>
To:     Nitin Rawat <quic_nitirawa@...cinc.com>
CC:     <mani@...nel.org>, <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>, <quic_cang@...cinc.com>,
        <quic_nguyenb@...cinc.com>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        "Naveen Kumar Goud Arepalli" <quic_narepall@...cinc.com>
Subject: Re: [PATCH V6 6/6] scsi: ufs: qcom: Configure clk HW division based
 on scaling conditions.

On Fri, Sep 01, 2023 at 05:13:36PM +0530, Nitin Rawat wrote:
> a) Enable internal HW division of unipro core_clk for scale up condition.
> b) Clear internal HW division of unipro core_clk for scale down condition.
> 

This commit message isn't good.

> Co-developed-by: Naveen Kumar Goud Arepalli <quic_narepall@...cinc.com>
> Signed-off-by: Naveen Kumar Goud Arepalli <quic_narepall@...cinc.com>
> Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
> ---
>  drivers/ufs/host/ufs-qcom.c | 31 +++++++++++++++++--------------
>  drivers/ufs/host/ufs-qcom.h |  2 +-
>  2 files changed, 18 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index c251c98a74f0..2ddda9356abc 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -1389,18 +1389,21 @@ static int ufs_qcom_set_core_clk_ctrl(struct ufs_hba *hba,
>  		core_clk_ctrl_reg |= FIELD_PREP(CLK_1US_CYCLES_MASK, cycles_in_1us);
>  	}
> 
> -	/* Clear CORE_CLK_DIV_EN */
> -	core_clk_ctrl_reg &= ~DME_VS_CORE_CLK_CTRL_CORE_CLK_DIV_EN_BIT;
> +	/* Enable CORE_CLK_DIV_EN for scale up condition */
> +	if (is_max_freq)
> +		core_clk_ctrl_reg |= CORE_CLK_DIV_EN_BIT;
> 
>  	ret = ufshcd_dme_set(hba,
>  			    UIC_ARG_MIB(DME_VS_CORE_CLK_CTRL),
>  			    core_clk_ctrl_reg);
> +	if (ret)
> +		return ret;

Nice, but don't mix logical and stylistic changes in the same patch.

>  	/*
>  	 * UFS host controller V4.0.0 onwards needs to program
>  	 * PA_VS_CORE_CLK_40NS_CYCLES attribute per programmed
>  	 * frequency of unipro core clk of UFS host controller.
>  	 */
> -	if (!ret && (host->hw_ver.major >= 4)) {
> +	if (host->hw_ver.major >= 4) {
>  		if (cycles_in_40ns > PA_VS_CORE_CLK_40NS_CYCLES_MASK)
>  			return -EINVAL;
> 
> @@ -1451,26 +1454,26 @@ static int ufs_qcom_clk_scale_up_post_change(struct ufs_hba *hba)
>  static int ufs_qcom_clk_scale_down_pre_change(struct ufs_hba *hba)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> -	int err;
> -	u32 core_clk_ctrl_reg;
> +	int ret;
> +	u32 reg;

This just obfuscates the logical changes you're making.


Frankly, I've been staring at this for several minutes now. The commit
message says there is a change here (but fails to describe what problem
is solves or what the change is)...but I can't find the change!

Regards,
Bjorn

> 
>  	if (!ufs_qcom_cap_qunipro(host))
>  		return 0;
> 
> -	err = ufshcd_dme_get(hba,
> +	ret = ufshcd_dme_get(hba,
>  			    UIC_ARG_MIB(DME_VS_CORE_CLK_CTRL),
> -			    &core_clk_ctrl_reg);
> +			    &reg);
> +	if (ret)
> +		return ret;
> 
>  	/* make sure CORE_CLK_DIV_EN is cleared */
> -	if (!err &&
> -	    (core_clk_ctrl_reg & DME_VS_CORE_CLK_CTRL_CORE_CLK_DIV_EN_BIT)) {
> -		core_clk_ctrl_reg &= ~DME_VS_CORE_CLK_CTRL_CORE_CLK_DIV_EN_BIT;
> -		err = ufshcd_dme_set(hba,
> +	if (reg & CORE_CLK_DIV_EN_BIT) {
> +		reg &= ~CORE_CLK_DIV_EN_BIT;
> +		ret = ufshcd_dme_set(hba,
>  				    UIC_ARG_MIB(DME_VS_CORE_CLK_CTRL),
> -				    core_clk_ctrl_reg);
> +				    reg);
>  	}
> -
> -	return err;
> +	return ret;
>  }
> 
>  static int ufs_qcom_clk_scale_down_post_change(struct ufs_hba *hba)
> diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
> index bc176ef58e3e..bf0c370c79c7 100644
> --- a/drivers/ufs/host/ufs-qcom.h
> +++ b/drivers/ufs/host/ufs-qcom.h
> @@ -141,7 +141,7 @@ enum {
>  /* bit and mask definitions for DME_VS_CORE_CLK_CTRL attribute */
>  #define CLK_1US_CYCLES_MASK_V4				GENMASK(27, 16)
>  #define CLK_1US_CYCLES_MASK				GENMASK(7, 0)
> -#define DME_VS_CORE_CLK_CTRL_CORE_CLK_DIV_EN_BIT	BIT(8)
> +#define CORE_CLK_DIV_EN_BIT				BIT(8)
>  #define PA_VS_CORE_CLK_40NS_CYCLES			0x9007
>  #define PA_VS_CORE_CLK_40NS_CYCLES_MASK			GENMASK(6, 0)
> 
> --
> 2.17.1
>