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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>
 <ee38105f-e2f4-4e40-3c89-224301f1eb12@quicinc.com>
 <YlbyptYB/VFUDF0Q@google.com>
From:   "Sandeep Maheswaram (Temp)" <quic_c_sanm@quicinc.com>
Message-ID: <df141dab-c9e6-17f9-43ed-af403db27bcb@quicinc.com>
Date:   Thu, 14 Apr 2022 11:27:31 +0530
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Hi Matthias,

On 4/13/2022 9:26 PM, Matthias Kaehlcke wrote:
> On Wed, Apr 13, 2022 at 02:38:33PM +0530, Sandeep Maheswaram (Temp) wrote:
>> 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 passed '&hcd->self.root_hub->dev'

Thanks. It is working with this change device_children_wakeup_capable 
(&hcd->self.root_hub->dev).

But I am not sure if it is better than usb_wakeup_enabled_descendants. 
Still we are accessing xhci layer

from dwc which Felipe suggested to avoid.

>
>> I was passing the dwc->dev like this device_children_wakeup_capable(dwc->dev) .Is it right?
> The DWC doesn't know anything about the connected USB devices, so this only
> checks wakeup capability/policy of the DWC itself.