Re: [PATCH v13 2/6] usb: dwc3: core: Host wake up support from system suspend

["Sandeep Maheswaram (Temp)" <quic_c_sanm@quicinc.com>]

Hi Pavan,

On 4/12/2022 10:30 AM, Pavan Kondeti wrote:
> Hi Sandeep,
>
> On Tue, Apr 12, 2022 at 10:16:39AM +0530, Sandeep Maheswaram (Temp) wrote:
>> Hi Matthias,
>>
>> On 4/12/2022 2:24 AM, Matthias Kaehlcke wrote:
>>> On Tue, Apr 12, 2022 at 12:46:50AM +0530, Sandeep Maheswaram wrote:
>>>> During suspend read the status of all port and set hs phy mode
>>>> based on current speed. Use this hs phy mode to configure wakeup
>>>> interrupts in qcom glue driver.
>>>>
>>>> Check wakep-source property for dwc3 core node to set the
>>> s/wakep/wakeup/
>> Okay. Will update in next version.
>>>> wakeup capability. Drop the device_init_wakeup call from
>>>> runtime suspend and resume.
>>>>
>>>> Also check during suspend if any wakeup capable devices are
>>>> connected to the controller (directly or through hubs), if there
>>>> are none set a flag to indicate that the PHY is powered
>>>> down during suspend.
>>>>
>>>> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@quicinc.com>
>>>> ---
>>> A per-patch change log would be really helpful for reviewers, even
>>> if it doesn't include older versions.
>> Okay. Will update in next version.
>>>>   drivers/usb/dwc3/core.c | 33 ++++++++++++++++++++-------------
>>>>   drivers/usb/dwc3/core.h |  4 ++++
>>>>   drivers/usb/dwc3/host.c | 25 +++++++++++++++++++++++++
>>>>   3 files changed, 49 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>>> index 1170b80..effaa43 100644
>>>> --- a/drivers/usb/dwc3/core.c
>>>> +++ b/drivers/usb/dwc3/core.c
>>>> @@ -32,6 +32,7 @@
>>>>   #include <linux/usb/gadget.h>
>>>>   #include <linux/usb/of.h>
>>>>   #include <linux/usb/otg.h>
>>>> +#include <linux/usb/hcd.h>
>>>>   #include "core.h"
>>>>   #include "gadget.h"
>>>> @@ -1723,6 +1724,7 @@ static int dwc3_probe(struct platform_device *pdev)
>>>>   	platform_set_drvdata(pdev, dwc);
>>>>   	dwc3_cache_hwparams(dwc);
>>>> +	device_init_wakeup(&pdev->dev, of_property_read_bool(dev->of_node, "wakeup-source"));
>>>>   	spin_lock_init(&dwc->lock);
>>>>   	mutex_init(&dwc->mutex);
>>>> @@ -1865,6 +1867,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>>>   {
>>>>   	unsigned long	flags;
>>>>   	u32 reg;
>>>> +	struct usb_hcd  *hcd = platform_get_drvdata(dwc->xhci);
>>>>   	switch (dwc->current_dr_role) {
>>>>   	case DWC3_GCTL_PRTCAP_DEVICE:
>>>> @@ -1877,10 +1880,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>>>   		dwc3_core_exit(dwc);
>>>>   		break;
>>>>   	case DWC3_GCTL_PRTCAP_HOST:
>>>> -		if (!PMSG_IS_AUTO(msg)) {
>>>> -			dwc3_core_exit(dwc);
>>>> -			break;
>>>> -		}
>>>> +		dwc3_check_phy_speed_mode(dwc);
>>>>   		/* Let controller to suspend HSPHY before PHY driver suspends */
>>>>   		if (dwc->dis_u2_susphy_quirk ||
>>>> @@ -1896,6 +1896,16 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>>>   		phy_pm_runtime_put_sync(dwc->usb2_generic_phy);
>>>>   		phy_pm_runtime_put_sync(dwc->usb3_generic_phy);
>>>> +
>>>> +		if (!PMSG_IS_AUTO(msg)) {
>>>> +			if (device_may_wakeup(dwc->dev) &&
>>>> +			    usb_wakeup_enabled_descendants(hcd->self.root_hub)) {
>>> You did not answer my question on v12, reposting it:
>>>
>>>    Did you ever try whether you could use device_children_wakeup_capable() from
>>>    [1] instead of usb_wakeup_enabled_descendants()?
>>>
>>>    [1] https://patchwork.kernel.org/project/linux-usb/patch/1635753224-23975-2-git-send-email-quic_c_sanm@quicinc.com/#24566065
>> Sorry ..I have replied in mail yesterday but it is not showing up in
>> patchwork link.
>>
>> Tried with  device_children_wakeup_capable(dwc->dev) instead of
>> usb_wakeup_enabled_descendants and it always returns true even
>>
>> when no devices are connected.
>>
> What do you mean by when no devices are connected? There is always
> root hub connected and we should not power down the DWC3 here even
> when remote wakeup for root hub is enabled. Essentially
> usb_wakeup_enabled_descendants() returns true even without any
> physical devices connected.
>
> What does device_children_wakeup_capable() do? Sorry, I could not
> find this function definition.
>
> Thanks,
> Pavan

usb_wakeup_enabled_descendants() doesn't consider hubs. It only returns true if any devices
are connected with wakeup capability apart from hubs. If we consider hubs also dwc3 core exit
and phy exit will never be called.

device_children_wakeup_capable() implementation was shared by Matthias in below thread
https://patchwork.kernel.org/project/linux-usb/patch/1635753224-23975-2-git-send-email-quic_c_sanm@quicinc.com/#24566065

Probably device_children_wakeup_capable() is returning true because it considers hubs also.