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

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Date:   Thu, 25 Mar 2021 03:25:19 +0530
From:   nitirawa@...eaurora.org
To:     Bjorn Andersson <bjorn.andersson@...aro.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 2021-03-23 20:58, Bjorn Andersson wrote:
> 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
>> 

Hi Bjorn,
Thanks for your review.
But As per the earlier discussion regarding handling of vcc voltage
for platform supporting both ufs 2.x and ufs 3.x , it was finally 
concluded to
use "vops and let vendors handle it, until specs or someone
has a better suggestion". Please correct me in case i am wrong.

https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2399116.html

Regards,
Nitin