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Date: Wed, 18 Aug 2021 14:44:13 +0530
From: Sandeep Maheswaram <sanm@...eaurora.org>
To: Felipe Balbi <balbi@...nel.org>,
Matthias Kaehlcke <mka@...omium.org>
Cc: Andy Gross <agross@...nel.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Stephen Boyd <swboyd@...omium.org>,
Doug Anderson <dianders@...omium.org>,
Mathias Nyman <mathias.nyman@...el.com>,
linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org,
Pratham Pratap <prathampratap@...eaurora.org>
Subject: Re: [PATCH v8 6/6] usb: dwc3: qcom: Keep power domain on to support
wakeup
Hi Felipe,
On 7/12/2021 3:12 PM, Felipe Balbi wrote:
> Hi,
>
> Matthias Kaehlcke <mka@...omium.org> writes:
>> On Mon, Jun 28, 2021 at 05:38:17PM +0530, Sandeep Maheswaram wrote:
>>> If wakeup capable devices are connected to the controller (directly
>>> or through hubs) at suspend time keep the power domain on in order
>>> to support wakeup from these devices.
>>>
>>> Signed-off-by: Sandeep Maheswaram <sanm@...eaurora.org>
>>> ---
>>> Checking phy_power_off flag instead of usb_wakeup_enabled_descendants
>>> to keep gdsc active.
>>>
>>> drivers/usb/dwc3/dwc3-qcom.c | 13 +++++++++++++
>>> 1 file changed, 13 insertions(+)
>>>
>>> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
>>> index 82125bc..ba31aa3 100644
>>> --- a/drivers/usb/dwc3/dwc3-qcom.c
>>> +++ b/drivers/usb/dwc3/dwc3-qcom.c
>>> @@ -17,6 +17,7 @@
>>> #include <linux/of_platform.h>
>>> #include <linux/platform_device.h>
>>> #include <linux/phy/phy.h>
>>> +#include <linux/pm_domain.h>
>>> #include <linux/usb/of.h>
>>> #include <linux/reset.h>
>>> #include <linux/iopoll.h>
>>> @@ -355,9 +356,15 @@ static int dwc3_qcom_suspend(struct dwc3_qcom *qcom)
>>> u32 val;
>>> int i, ret;
>>>
>>> + struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
>>> + struct generic_pm_domain *genpd = pd_to_genpd(qcom->dev->pm_domain);
>>> +
>>> if (qcom->is_suspended)
>>> return 0;
>>>
>>> + if (!dwc->phy_power_off && dwc->xhci)
>>> + genpd->flags |= GENPD_FLAG_ACTIVE_WAKEUP;
>>> +
>>> val = readl(qcom->qscratch_base + PWR_EVNT_IRQ_STAT_REG);
>>> if (!(val & PWR_EVNT_LPM_IN_L2_MASK))
>>> dev_err(qcom->dev, "HS-PHY not in L2\n");
>>> @@ -382,9 +389,15 @@ static int dwc3_qcom_resume(struct dwc3_qcom *qcom)
>>> int ret;
>>> int i;
>>>
>>> + struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
>>> + struct generic_pm_domain *genpd = pd_to_genpd(qcom->dev->pm_domain);
>>> +
>>> if (!qcom->is_suspended)
>>> return 0;
>>>
>>> + if (dwc->xhci)
>>> + genpd->flags &= ~GENPD_FLAG_ACTIVE_WAKEUP;
>>> +
>>> if (device_may_wakeup(qcom->dev))
>>> dwc3_qcom_disable_interrupts(qcom);
>>>
>> This is essentially the same as v7, which Felipe NAKed
>> (https://patchwork.kernel.org/project/linux-arm-msm/patch/1619586716-8687-6-git-send-email-sanm@codeaurora.org/)
>>
>> I think Felipe wants to see the handling of the power domain in the
>> xhci-plat driver. One problem here is that the power domain is owned
> this is not exactly what I meant to say, though. I want drivers to be
> self-contained. I.e. dwc3 doesn't modify xhci data and vice-versa. There
> are a few assummpmtions that we can make, though. The structure is
> usually like this:
>
> glue {
> dwc3 {
> xhci
> };
> };
>
> This means that in order for glue_suspend() to run, dwc3 has to suspend
> first and xhci has to suspend before dwc3.
>
> For example, in the suspend call above, qcom (the glue) is directly
> accessing dwc3 core data, which is incorrect. It looks like we want to
> know if the PHY is not powered off and if it isn't, then we want to
> change the power domain ACTIVE_WAKEUP flag. Now, phy_power_off is false
> whenever any of xHCI's children enable USB wakeup.
>
> It seems like we need to way to generically propagate that knowledge up
> the parent tree. I.e., a parent needs to know if its child is wakeup
> capable, then dwc3 could, in its suspend routine:
>
> static int dwc3_suspend(struct device *dev)
> {
> /* ... */
>
> if (device_children_wakeup_capable(dev))
> device_enable_wakeup(dev);
>
> /* ... */
> }
Can we use like this device_may_wakeup(&dwc->xhci->dev) to check if
children is wakeup capable like below ?
static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
{
/* ... */
if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(&dwc->xhci->dev)) {
dwc3_core_exit(dwc);
break;
}
/* ... */
}
> and similarly for qcom glue:
>
> static int dwc3_qcom_suspend(struct device *dev)
> {
> /* ... */
>
>
> if (device_children_wakeup_capable(dev)) {
> device_enable_wakeup(dev);
> genpd->flags |= GENPD_FLAG_ACTIVE_WAKEUP;
> }
>
> /* ... */
> }
>
> It also seems plausible that this could be done at driver core and
> completely hidden away from drivers.
And in qcom glue like this
static int dwc3_qcom_suspend(struct dwc3_qcom *qcom)
{
/* ... */
struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
if (device_may_wakeup(&dwc->xhci->dev) && dwc->xhci)
genpd->flags |= GENPD_FLAG_ACTIVE_WAKEUP;
/* ... */
}
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