[PATCH v3 7/8] scsi: ufs: core: Toggle Write Booster during clock scaling base on gear speed

Ziqi Chen
2025-02-03T08:13:15Z

From: Can Guo <quic_cang@quicinc.com>

During clock scaling, Write Booster is toggled on or off based on
whether the clock is scaled up or down. However, with OPP V2 powered
multi-level gear scaling, the gear can be scaled amongst multiple gear
speeds, e.g., it may scale down from G5 to G4, or from G4 to G2. To provide
flexibilities, add a new field for clock scaling such that during clock
scaling Write Booster can be enabled or disabled based on gear speeds but
not based on scaling up or down.

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:
Initialize the local variables "wb_en" as "false".
---
drivers/ufs/core/ufshcd.c | 17 ++++++++++++-----
include/ufs/ufshcd.h | 3 +++
2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index bd93119a177d..83fd38c78467 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1393,13 +1393,17 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba, u64 timeout_us)
return ret;
}

-static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int err, bool scale_up)
+static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int err)
{
up_write(&hba->clk_scaling_lock);

- /* Enable Write Booster if we have scaled up else disable it */
- if (ufshcd_enable_wb_if_scaling_up(hba) && !err)
- ufshcd_wb_toggle(hba, scale_up);
+ /* Enable Write Booster if current gear requires it else disable it */
+ if (ufshcd_enable_wb_if_scaling_up(hba) && !err) {
+ bool wb_en = false;
+
+ wb_en = hba->pwr_info.gear_rx >= hba->clk_scaling.wb_gear ? true : false;
+ ufshcd_wb_toggle(hba, wb_en);
+ }

mutex_unlock(&hba->wb_mutex);

@@ -1461,7 +1465,7 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
}

out_unprepare:
- ufshcd_clock_scaling_unprepare(hba, ret, scale_up);
+ ufshcd_clock_scaling_unprepare(hba, ret);
return ret;
}

@@ -1821,6 +1825,9 @@ static void ufshcd_init_clk_scaling(struct ufs_hba *hba)
if (!hba->clk_scaling.min_gear)
hba->clk_scaling.min_gear = UFS_HS_G1;

+ if (!hba->clk_scaling.wb_gear)
+ hba->clk_scaling.wb_gear = UFS_HS_G3;
+
INIT_WORK(&hba->clk_scaling.suspend_work,
ufshcd_clk_scaling_suspend_work);
INIT_WORK(&hba->clk_scaling.resume_work,
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index cdb853f5b871..efca700d0520 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -447,6 +447,8 @@ struct ufs_clk_gating {
* @resume_work: worker to resume devfreq
* @target_freq: frequency requested by devfreq framework
* @min_gear: lowest HS gear to scale down to
+ * @wb_gear: enable Write Booster when HS gear scales above or equal to it, else
+ * disable Write Booster
* @is_enabled: tracks if scaling is currently enabled or not, controlled by
* clkscale_enable sysfs node
* @is_allowed: tracks if scaling is currently allowed or not, used to block
@@ -467,6 +469,7 @@ struct ufs_clk_scaling {
struct work_struct resume_work;
unsigned long target_freq;
u32 min_gear;
+ u32 wb_gear;
bool is_enabled;
bool is_allowed;
bool is_initialized;
--
2.34.1