[PATCH v3 5/8] scsi: ufs: core: Enable multi-level gear scaling

Ziqi Chen
2025-02-03T08:13:04Z

From: Can Guo <quic_cang@quicinc.com>

With OPP V2 enabled, devfreq can scale clocks amongst multiple frequency
plans. However, the gear speed is only toggled between min and max during
clock scaling. Enable multi-level gear scaling by mapping clock frequencies
to gear speeds, so that when devfreq scales clock frequencies we can put
the UFS link at the appropraite gear speeds accordingly.

Signed-off-by: Can Guo <quic_cang@quicinc.com>
Co-developed-by: Ziqi Chen <quic_ziqichen@quicinc.com>
Signed-off-by: Ziqi Chen <quic_ziqichen@quicinc.com>
---

v1 -> v2:
Rename the lable "do_pmc" to "config_pwr_mode".

v2 -> v3:
Use assignment instead memcpy() in function ufshcd_scale_gear().
---
drivers/ufs/core/ufshcd.c | 51 +++++++++++++++++++++++++++++++--------
1 file changed, 41 insertions(+), 10 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 8d295cc827cc..ebab897080a6 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1308,16 +1308,26 @@ static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
/**
* ufshcd_scale_gear - scale up/down UFS gear
* @hba: per adapter instance
+ * @target_gear: target gear to scale to
* @scale_up: True for scaling up gear and false for scaling down
*
* Return: 0 for success; -EBUSY if scaling can't happen at this time;
* non-zero for any other errors.
*/
-static int ufshcd_scale_gear(struct ufs_hba *hba, bool scale_up)
+static int ufshcd_scale_gear(struct ufs_hba *hba, u32 target_gear, bool scale_up)
{
int ret = 0;
struct ufs_pa_layer_attr new_pwr_info;

+ if (target_gear) {
+ new_pwr_info = hba->pwr_info;
+ new_pwr_info.gear_tx = target_gear;
+ new_pwr_info.gear_rx = target_gear;
+
+ goto config_pwr_mode;
+ }
+
+ /* Legacy gear scaling, in case vops_freq_to_gear_speed() is not implemented */
if (scale_up) {
memcpy(&new_pwr_info, &hba->clk_scaling.saved_pwr_info,
sizeof(struct ufs_pa_layer_attr));
@@ -1338,6 +1348,7 @@ static int ufshcd_scale_gear(struct ufs_hba *hba, bool scale_up)
}
}

+config_pwr_mode:
/* check if the power mode needs to be changed or not? */
ret = ufshcd_config_pwr_mode(hba, &new_pwr_info);
if (ret)
@@ -1408,15 +1419,26 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int err, bool sc
static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
bool scale_up)
{
+ u32 old_gear = hba->pwr_info.gear_rx;
+ int new_gear = 0;
int ret = 0;

+ new_gear = ufshcd_vops_freq_to_gear_speed(hba, freq);
+ if (new_gear < 0)
+ /*
+ * return negative value means that the vops_freq_to_gear_speed() is not
+ * implemented or didn't find matched gear speed, assign '0' to new_gear
+ * to switch to legacy gear scaling sequence in ufshcd_scale_gear().
+ */
+ new_gear = 0;
+
ret = ufshcd_clock_scaling_prepare(hba, 1 * USEC_PER_SEC);
if (ret)
return ret;

/* scale down the gear before scaling down clocks */
if (!scale_up) {
- ret = ufshcd_scale_gear(hba, false);
+ ret = ufshcd_scale_gear(hba, (u32)new_gear, false);
if (ret)
goto out_unprepare;
}
@@ -1424,13 +1446,13 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
ret = ufshcd_scale_clks(hba, freq, scale_up);
if (ret) {
if (!scale_up)
- ufshcd_scale_gear(hba, true);
+ ufshcd_scale_gear(hba, old_gear, true);
goto out_unprepare;
}

/* scale up the gear after scaling up clocks */
if (scale_up) {
- ret = ufshcd_scale_gear(hba, true);
+ ret = ufshcd_scale_gear(hba, (u32)new_gear, true);
if (ret) {
ufshcd_scale_clks(hba, hba->devfreq->previous_freq,
false);
@@ -1723,6 +1745,8 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct ufs_hba *hba = dev_get_drvdata(dev);
+ struct ufs_clk_info *clki;
+ unsigned long freq;
u32 value;
int err = 0;

@@ -1746,14 +1770,21 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,

if (value) {
ufshcd_resume_clkscaling(hba);
- } else {
- ufshcd_suspend_clkscaling(hba);
- err = ufshcd_devfreq_scale(hba, ULONG_MAX, true);
- if (err)
- dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
- __func__, err);
+ goto out_rel;
}

+ clki = list_first_entry(&hba->clk_list_head, struct ufs_clk_info, list);
+ freq = clki->max_freq;
+
+ ufshcd_suspend_clkscaling(hba);
+ err = ufshcd_devfreq_scale(hba, freq, true);
+ if (err)
+ dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
+ __func__, err);
+ else
+ hba->clk_scaling.target_freq = freq;
+
+out_rel:
ufshcd_release(hba);
ufshcd_rpm_put_sync(hba);
out:
--
2.34.1