Re: [PATCH 3/3] clk: qcom: gcc-sc7280: Update the .pwrsts for usb gdsc

Krishna Kurapati PSSNV
2022-09-14T08:42:27Z

On 9/14/2022 12:39 PM, Johan Hovold wrote:
> On Thu, Sep 01, 2022 at 03:47:56PM +0530, Rajendra Nayak wrote:
>> USB on sc7280 cannot support wakeups from low power states
>> if the GDSC is turned OFF. Update the .pwrsts for usb GDSC so it
>> only transitions to RET in low power.
>
> It seems this isn't just needed for wakeup to work. On both sc7280 and
> sc8280xp the controller doesn't resume properly if the domain has been
> powered off (i.e. regardless of whether wakeup is enabled or not).
>
Hi Johan,

I believe you are referring to the reinit that happens in xhci resume
path after wakeup happens:

[ 48.675839] xhci-hcd xhci-hcd.14.auto: xHC error in resume, USBSTS
0x411, Reinit

I see that when USB GDSC is not in retention, we don't retain controller
state and go for reinit and re-enum of connected devices. We are seeing
an additional delay of around ~0.7 sec (in chromebooks running on
SC7280) in the wakeup path for re-enumeration of connected USB devices.
To avoid this, we wanted to put GDSC in retention during PM suspend.

> Are you sure there's no state that needs to be retained regardless of
> the wakeup setting?
>
>> Signed-off-by: Rajendra Nayak <quic_rjendra@quicinc.com>
>> ---
>> drivers/clk/qcom/gcc-sc7280.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/qcom/gcc-sc7280.c b/drivers/clk/qcom/gcc-sc7280.c
>> index 7ff64d4d5920..de29a034e725 100644
>> --- a/drivers/clk/qcom/gcc-sc7280.c
>> +++ b/drivers/clk/qcom/gcc-sc7280.c
>> @@ -3126,7 +3126,7 @@ static struct gdsc gcc_usb30_prim_gdsc = {
>> .pd = {
>> .name = "gcc_usb30_prim_gdsc",
>> },
>> - .pwrsts = PWRSTS_OFF_ON,
>> + .pwrsts = PWRSTS_RET_ON,
>> .flags = VOTABLE,
>> };
>
> And what about gcc_usb30_sec_gdsc?

Currently wakeup is not enabled on secondary controller as its not
required for end product platform (herobrine variant). So leaving the
usb30_sec_gdsc as it is for now.

Regards,
Krishna,