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

From: Sandeep Maheswaram (Temp)
Date: Thu Apr 14 2022 - 01:57:49 EST

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@xxxxxxxxxxx>
---
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@xxxxxxxxxxx/#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@xxxxxxxxxxx/#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.