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Subject: Re: [PATCH v13 2/6] usb: dwc3: core: Host wake up support from system
 suspend
To:     Matthias Kaehlcke <mka@chromium.org>
CC:     Pavan Kondeti <quic_pkondeti@quicinc.com>,
        Rob Herring <robh+dt@kernel.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Felipe Balbi <balbi@kernel.org>,
        Stephen Boyd <swboyd@chromium.org>,
        Doug Anderson <dianders@chromium.org>,
        Mathias Nyman <mathias.nyman@intel.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        <devicetree@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <quic_ppratap@quicinc.com>, <quic_kriskura@quicinc.com>,
        <quic_vpulyala@quicinc.com>
References: <1649704614-31518-1-git-send-email-quic_c_sanm@quicinc.com>
 <1649704614-31518-3-git-send-email-quic_c_sanm@quicinc.com>
 <YlSVec5+SpdMZWCz@google.com>
 <36d22ad7-7f11-2f63-cd68-5d564476161e@quicinc.com>
 <20220412050018.GB2627@hu-pkondeti-hyd.qualcomm.com>
 <259c9e87-a52e-c063-7901-2c6decd42675@quicinc.com>
 <YlXNd5YkAMW7cbYG@google.com>
From:   "Sandeep Maheswaram (Temp)" <quic_c_sanm@quicinc.com>
Message-ID: <ee38105f-e2f4-4e40-3c89-224301f1eb12@quicinc.com>
Date:   Wed, 13 Apr 2022 14:38:33 +0530
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Hi Matthias,

On 4/13/2022 12:35 AM, Matthias Kaehlcke wrote:
> On Tue, Apr 12, 2022 at 12:08:02PM +0530, Sandeep Maheswaram (Temp) wrote:
>> 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.
> Actually it considers hubs:
>
> unsigned usb_wakeup_enabled_descendants(struct usb_device *udev)
> {
> 	struct usb_hub *hub = usb_hub_to_struct_hub(udev);
>
> 	return udev->do_remote_wakeup +
> 		(hub ? hub->wakeup_enabled_descendants : 0);
> }
>
> 'udev' may or may not be a hub, if 'do_remote_wakeup' is set then the
> device is considered a wakeup enabled descendant.
>
> And for system suspebd 'do_remote_wakeup' is set based on the wakeup
> config of the device:
>
> static void choose_wakeup(struct usb_device *udev, pm_message_t msg)
> {
> 	...
> 	w = device_may_wakeup(&udev->dev);
> 	...
> 	udev->do_remote_wakeup = w;
> }
>
> I checked on three systems with different Linux distributions, on all of
> the wakeup flag of a connected hub is 'disabled'. Wakeup still works, so
> apparently that flag doesn't really have an impact for child ports.
>
>> 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.
> I thought I did a basic test when I sent the patch, I did another (?) one
> with v13 of your patch set. In this tests with a hub connected the
> function returns true when an HID device is connected, and false when
> nothing is connected. The wakeup flag of the hub is disabled (default).
>
> Sandeep, are the wakeup flags of the child hub(s) set to 'enabled' on
> the system you tested on?

The wakeup flags of hub is 'disabled' on system I tested.

What is the input param you are giving to device_children_wakeup_capable() function ?

I was passing the dwc->dev like this device_children_wakeup_capable(dwc->dev) .Is it right?

Regards
Sandeep