On 2020-02-07 04:33, Bjorn Andersson wrote:
On Thu 06 Feb 00:33 PST 2020, Can Guo wrote:
After enter hibern8, as UFS JEDEC ver 3.0 requires, a specific gating
wait
time is required before disable the device reference clock. If it is
not
specified, use the old delay.
Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
Reviewed-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
Reviewed-by: Hongwu Su <hongwus@xxxxxxxxxxxxxx>
---
drivers/scsi/ufs/ufs-qcom.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index 85d7c17..39eefa4 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -833,6 +833,8 @@ static int ufs_qcom_bus_register(struct
ufs_qcom_host *host)
static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host,
bool enable)
{
+ unsigned long gating_wait;
+
if (host->dev_ref_clk_ctrl_mmio &&
(enable ^ host->is_dev_ref_clk_enabled)) {
u32 temp = readl_relaxed(host->dev_ref_clk_ctrl_mmio);
@@ -845,11 +847,25 @@ static void ufs_qcom_dev_ref_clk_ctrl(struct
ufs_qcom_host *host, bool enable)
/*
* If we are here to disable this clock it might be immediately
* after entering into hibern8 in which case we need to make
- * sure that device ref_clk is active at least 1us after the
+ * sure that device ref_clk is active for specific time after
* hibern8 enter.
*/
- if (!enable)
- udelay(1);
+ if (!enable) {
+ gating_wait = host->hba->dev_info.clk_gating_wait_us;
+ if (!gating_wait) {
Afaict this can't happen, because in patch 6 you check for gating_wait
being 0 and if so set it to 0xff.
Sorry, I was intended to give clk_gating_wait_us values only if it is
a UFS3.0 device. I will revise patch 6/8.
+ udelay(1);
+ } else {
+ /*
+ * bRefClkGatingWaitTime defines the minimum
+ * time for which the reference clock is
+ * required by device during transition from
+ * HS-MODE to LS-MODE or HIBERN8 state. Give it
+ * more time to be on the safe side.
+ */
+ gating_wait += 10;
+ usleep_range(gating_wait, gating_wait + 10);
I presume there's no strong requirement on the max, so how about using
a
substantially larger max - say 1k, or 10k - to allow the usleep_range()
to do it's job?
PS. Please include linux-arm-msm@ on all the patches in the series, not
just two of them.
Regards,
Bjorn
bRefClkGatingWaitTime, as vendor defined in their device attribute is
usually
around 50~100, 1k or 10k delay makes it too large. usleep_range() works
well
so long as the delay is within (10us - 20ms), so I added 10 to make sure
it is
above 10us.
SLEEPING FOR ~USECS OR SMALL MSECS ( 10us - 20ms):
* Use usleep_range
https://www.kernel.org/doc/Documentation/timers/timers-howto.txt
Thanks,
Can Guo.
+ }
+ }
writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio);
--
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