linux-kernel - Re: [PATCH V2 3/3] scsi: ufs-qcom: configure VCC voltage level in vendor file

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Date:   Tue, 23 Mar 2021 10:28:34 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Nitin Rawat <nitirawa@...eaurora.org>
Cc:     asutoshd@...eaurora.org, cang@...eaurora.org,
        stummala@...eaurora.org, vbadigan@...eaurora.org,
        alim.akhtar@...sung.com, avri.altman@....com, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, stanley.chu@...iatek.com,
        beanhuo@...ron.com, adrian.hunter@...el.com, bvanassche@....org,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 3/3] scsi: ufs-qcom: configure VCC voltage level in
 vendor file

On Sun 21 Mar 16:57 CDT 2021, Nitin Rawat wrote:

> As a part of vops handler, VCC voltage is updated
> as per the ufs device probed after reading the device
> descriptor. We follow below steps to configure voltage
> level.
> 
> 1. Set the device to SLEEP state.
> 2. Disable the Vcc Regulator.
> 3. Set the vcc voltage according to the device type and reenable
>    the regulator.
> 4. Set the device mode back to ACTIVE.
> 

When we discussed this a while back this was described as a requirement
from the device specification, you only operate on objects "owned" by
ufshcd and you invoke ufshcd operations to perform the actions.

So why is this a ufs-qcom patch and not something in ufshcd?

Regards,
Bjorn

> Signed-off-by: Nitin Rawat <nitirawa@...eaurora.org>
> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
> ---
>  drivers/scsi/ufs/ufs-qcom.c | 51 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index f97d7b0..ca35f5c 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -21,6 +21,17 @@
>  #define UFS_QCOM_DEFAULT_DBG_PRINT_EN	\
>  	(UFS_QCOM_DBG_PRINT_REGS_EN | UFS_QCOM_DBG_PRINT_TEST_BUS_EN)
> 
> +#define	ANDROID_BOOT_DEV_MAX	30
> +static char android_boot_dev[ANDROID_BOOT_DEV_MAX];
> +
> +/* Min and Max VCC voltage values for ufs 2.x and
> + * ufs 3.x devices
> + */
> +#define UFS_3X_VREG_VCC_MIN_UV	2540000 /* uV */
> +#define UFS_3X_VREG_VCC_MAX_UV	2700000 /* uV */
> +#define UFS_2X_VREG_VCC_MIN_UV	2950000 /* uV */
> +#define UFS_2X_VREG_VCC_MAX_UV	2960000 /* uV */
> +
>  enum {
>  	TSTBUS_UAWM,
>  	TSTBUS_UARM,
> @@ -1293,6 +1304,45 @@ static void ufs_qcom_print_hw_debug_reg_all(struct ufs_hba *hba,
>  	print_fn(hba, reg, 9, "UFS_DBG_RD_REG_TMRLUT ", priv);
>  }
> 
> +  /**
> +   * ufs_qcom_setup_vcc_regulators - Update VCC voltage
> +   * @hba: host controller instance
> +   * Update VCC voltage based on UFS device(ufs 2.x or
> +   * ufs 3.x probed)
> +   */
> +static int ufs_qcom_setup_vcc_regulators(struct ufs_hba *hba)
> +{
> +	struct ufs_dev_info *dev_info = &hba->dev_info;
> +	struct ufs_vreg *vreg = hba->vreg_info.vcc;
> +	int ret;
> +
> +	/* Put the device in sleep before lowering VCC level */
> +	ret = ufshcd_set_dev_pwr_mode(hba, UFS_SLEEP_PWR_MODE);
> +
> +	/* Switch off VCC before switching it ON at 2.5v or 2.96v */
> +	ret = ufshcd_disable_vreg(hba->dev, vreg);
> +
> +	/* add ~2ms delay before renabling VCC at lower voltage */
> +	usleep_range(2000, 2100);
> +
> +	/* set VCC min and max voltage according to ufs device type */
> +	if (dev_info->wspecversion >= 0x300) {
> +		vreg->min_uV = UFS_3X_VREG_VCC_MIN_UV;
> +		vreg->max_uV = UFS_3X_VREG_VCC_MAX_UV;
> +	}
> +
> +	else {
> +		vreg->min_uV = UFS_2X_VREG_VCC_MIN_UV;
> +		vreg->max_uV = UFS_2X_VREG_VCC_MAX_UV;
> +	}
> +
> +	ret = ufshcd_enable_vreg(hba->dev, vreg);
> +
> +	/* Bring the device in active now */
> +	ret = ufshcd_set_dev_pwr_mode(hba, UFS_ACTIVE_PWR_MODE);
> +	return ret;
> +}
> +
>  static void ufs_qcom_enable_test_bus(struct ufs_qcom_host *host)
>  {
>  	if (host->dbg_print_en & UFS_QCOM_DBG_PRINT_TEST_BUS_EN) {
> @@ -1490,6 +1540,7 @@ static const struct ufs_hba_variant_ops ufs_hba_qcom_vops = {
>  	.device_reset		= ufs_qcom_device_reset,
>  	.config_scaling_param = ufs_qcom_config_scaling_param,
>  	.program_key		= ufs_qcom_ice_program_key,
> +	.setup_vcc_regulators	= ufs_qcom_setup_vcc_regulators,
>  };
> 
>  /**
> --
> 2.7.4
>