Re: [PATCH V5 09/11] scsi: ufs: qcom : Refactor phy_power_on/off calls

Nitin Rawat
2025-05-21T21:41:22Z

On 5/21/2025 7:27 PM, Manivannan Sadhasivam wrote:
> On Thu, May 15, 2025 at 09:57:20PM +0530, Nitin Rawat wrote:
>> Commit 3f6d1767b1a0 ("phy: ufs-qcom: Refactor all init steps into
>> phy_poweron") removes the phy_power_on/off from ufs_qcom_setup_clocks
>
> s/removes/moved

Sure, will address in next patchset.

>
>> to suspend/resume func.
>>
>> To have a better power saving, remove the phy_power_on/off calls from
>> resume/suspend path and put them back to ufs_qcom_setup_clocks, so that
>> PHY regulators & clks can be turned on/off along with UFS's clocks.
>>
>> Since phy phy_power_on is separated out from phy calibrate, make
>> separate calls to phy_power_on and phy_calibrate calls from ufs qcom
>> driver.
>>
>
> This patch is not calling phy_calibrate().

updated commit text to remove phy_Calibrate from commit text

>
>> Co-developed-by: Can Guo <quic_cang@quicinc.com>
>> Signed-off-by: Can Guo <quic_cang@quicinc.com>
>> Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.com>
>> ---
>> drivers/ufs/host/ufs-qcom.c | 61 ++++++++++++++++++-------------------
>> 1 file changed, 29 insertions(+), 32 deletions(-)
>>
>
> [...]
>
>> static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>> enum ufs_notify_change_status status)
>> {
>> struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> + struct phy *phy = host->generic_phy;
>> + int err;
>>
>> /*
>> * In case ufs_qcom_init() is not yet done, simply ignore.
>> @@ -1157,10 +1141,22 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>> /* disable device ref_clk */
>> ufs_qcom_dev_ref_clk_ctrl(host, false);
>> }
>> +
>> + err = phy_power_off(phy);
>> + if (err) {
>> + dev_err(hba->dev, "phy power off failed, ret=%d\n", err);
>> + return err;
>> + }
>> }
>> break;
>> case POST_CHANGE:
>> if (on) {
>> + err = phy_power_on(phy);
>> + if (err) {
>> + dev_err(hba->dev, "phy power on failed, ret = %d\n", err);
>> + return err;
>> + }
>> +
>> /* enable the device ref clock for HS mode*/
>> if (ufshcd_is_hs_mode(&hba->pwr_info))
>> ufs_qcom_dev_ref_clk_ctrl(host, true);
>> @@ -1343,9 +1339,10 @@ static int ufs_qcom_init(struct ufs_hba *hba)
>> static void ufs_qcom_exit(struct ufs_hba *hba)
>> {
>> struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> + struct phy *phy = host->generic_phy;
>>
>> ufs_qcom_disable_lane_clks(host);
>> - phy_power_off(host->generic_phy);
>> + phy_power_off(phy);
>
> This change is not at all needed.

In the current code, PHY resources (clocks and rails) remain active even
when the link is in a hibernate state and all controller clocks are off.
This results in a significant power penalty and can prevent CX power
collapse.

These rails and clocks are only turned off when a system suspend is
triggered, and even then, only at SPM level 5 where the link is turned
off. This approach is not power-efficient.

As part of this series, the code that enables/disables the PHY's
regulators and clocks is now confined to the phy_power_on and
phy_power_off calls, with the rest moved to the calibration phase.

Therefore, we are invoking the phy_power_off and phy_power_on calls from
ufs_qcom_setup_clocks, ensuring that the PHY's regulators and clocks can
be turned on/off along with the UFS clocks, thereby achieving power savings.

Therefore, this patch is the cornerstone of this series.

Regards,
Nitin

>
> - Mani
>