[lkml]   [2018]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v3 1/6] phy: qcom-qmp: Enable pipe_clk before checking USB3 PHY_STATUS
Hi Doug,

On 3/27/2018 9:56 AM, Doug Anderson wrote:
> Manu
> On Thu, Mar 22, 2018 at 11:11 PM, Manu Gautam <> wrote:
>> QMP PHY for USB mode requires pipe_clk for calibration and PLL lock
>> to take place. This clock is output from PHY to GCC clock_ctl and then
>> fed back to QMP PHY and is available from PHY only after PHY is reset
>> and initialized, hence it can't be enabled too early in initialization
>> sequence.
>> Signed-off-by: Manu Gautam <>
>> ---
>> drivers/phy/qualcomm/phy-qcom-qmp.c | 33 ++++++++++++++++++++++++++++++++-
>> 1 file changed, 32 insertions(+), 1 deletion(-)
> So it's now new with this patch, but it's more obvious with this
> patch. It seems like "UFS/PCIE" is kinda broken w/ respect to how it
> controls its clock. Specifically:
> * If you init the PHY but don't power it on, then you "exit" the PHY:
> you'll disable/unprepare "pipe_clk" even though you never
> prepare/enabled it.
> * If you init the PHY, power it on, power it off, power it on, and
> exit the PHY: you'll leave the clock prepared one extra time.
> Specifically I'd expect: for UFS/PCIE the disable/unprepare should be
> symmetric with the enable/prepare and should be in "power off", not in
> exit.
> ...or did I miss something?
> Interestingly, your patch fixes this problem for USB3 (where init/exit
> are now symmetric), but leaves the problem there for UFS/PCIE.

Thanks for review.
One of the reason why pipe_clk is disabled as part of phy_exit is that
halt_check from clk_disable reports error if called after PHY has been
powered down or phy_exit.
I believe that warning should be ignored in qcom gcc-clock driver
(for applicable platforms) by using BRANCH_HALT_DELAY as halt_check
for pipe_clk and performing clk_disable from power_off for UFS/PCIE.

I can implement that as separate patch once dependent gcc driver
patch(es) gets in. Would that be ok?


The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

 \ /
  Last update: 2018-03-27 07:07    [W:0.096 / U:0.196 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site