Thanks Kim for the response.
On 2016-10-06 03:28, Kiwoong Kim wrote:
Hi, Subhash.
Some UFS host controllers may need to call the vendor specific callback
before and after controlling by clock control framework,
regardless of whether available clocks are turned on or off.
Are you suggesting to call ufshcd_vops_setup_clocks() 2 times, one
before the on/off by ufshcd core driver and one after the on/off? If
yes, then we also have add 3rd argument clarifying if this is PRE_CHANGE
or POST_CHANGE.
Is there any special reason to limit to invoke the callback
only when the clocks are turned on or not?
Besides, the callback is acknowledged from core driver
because 2nd argument is whether the clocks are turned on or not.
If you have any other idea, please let me know.
This is my suggestion:
1. Add 3rd argument to setup_clocks ops to let the vendor callback
function know if this is called PRE_CHANGE or POST_CHANGE.
2. If #1 is in place, call setup_clocks 2 times, one with PRE_CHANGE
argument before making any clock changes in core driver, 2nd with
POST_CHANGE argument after making the clock changes to core driver.
Let me know if this would work or not.
Thanks,
Subhash
Thanks
Regards
Vendor specific setup_clocks callback may require the clocks managed
by ufshcd driver to be ON. So if the vendor specific setup_clocks
callback
is called while the required clocks are turned off, it could result
into
unclocked register access.
To prevent possible unclock register access, this change makes sure
that
required clocks remain enabled before calling into vendor specific
setup_clocks callback.
Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
---
Changes from v2:
* Don't call ufshcd_vops_setup_clocks() again for clock off
---
drivers/scsi/ufs/ufshcd.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 05c7456..c1a77d3 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5389,6 +5389,17 @@ static int __ufshcd_setup_clocks(struct ufs_hba
*hba, bool on,
if (!head || list_empty(head))
goto out;
+ /*
+ * vendor specific setup_clocks ops may depend on clocks managed by
+ * this standard driver hence call the vendor specific setup_clocks
+ * before disabling the clocks managed here.
+ */
+ if (!on) {
+ ret = ufshcd_vops_setup_clocks(hba, on);
+ if (ret)
+ return ret;
+ }
+
list_for_each_entry(clki, head, list) {
if (!IS_ERR_OR_NULL(clki->clk)) {
if (skip_ref_clk && !strcmp(clki->name, "ref_clk"))
@@ -5410,7 +5421,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba
*hba, bool on,
}
}
- ret = ufshcd_vops_setup_clocks(hba, on);
+ /*
+ * vendor specific setup_clocks ops may depend on clocks managed by
+ * this standard driver hence call the vendor specific setup_clocks
+ * after enabling the clocks managed here.
+ */
+ if (on) {
+ ret = ufshcd_vops_setup_clocks(hba, on);
+ if (ret)
+ return ret;
+ }
out:
if (ret) {
list_for_each_entry(clki, head, list) {
--
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