On 11/05/2014 03:48 AM, Pratyush Anand wrote: > On Wed, Nov 05, 2014 at 10:53:35AM +0530, Pratyush Anand wrote: >> Hello Joe, >> >> On Wed, Nov 05, 2014 at 06:20:06AM +0800, Joseph Salisbury wrote: >>> Hello Pratyush, >>> >>> A kernel bug report was opened against Ubuntu [0]. After a kernel >>> bisect, it was found that reverting the following commit resolved this bug: >>> >>> commit a40178b2fa6ad87670fb1e5fa4024db00c149629 >>> Author: Pratyush Anand <pratyush.anand@xxxxxx> >>> Date: Fri Jul 18 12:37:10 2014 +0530 >>> >>> USB: Fix persist resume of some SS USB devices >>> >>> The regression was introduced as of v3.17-rc1. The regression still >>> exists in the 3.18-rc3 mainline kernel, and has made it's way into the >>> stable kernels. >> Its strange, as per my understanding patch does not introduce any side >> effect for devices whose resume time is normal. So, if a device is >> connected to the SS port and it was working after resume from >> suspend to ram without this patch, then that device should still work >> with this patch. >> >> Infact this has resolved another bug reported to bugzilla >> https://bugzilla.kernel.org/show_bug.cgi?id=53211 >> >> >>> I was hoping to get your feedback, since you are the patch author. Do >>> you think gathering any additional data will help diagnose this issue, >> Yaa, sure additional info will help to understand the issue. >> -- dmesg log of suspend resume when this patch is not applied and also >> when applied. > I see that you have already provided both log to the buglink. I had a > look on that. > > > When it fails (with this patch): > Oct 22 15:38:59 mana kernel: [ 59.825122] PM: resume of devices > complete after 22223.878 msecs > > When it passed (without this patch): > Oct 22 15:37:19 mana kernel: [ 53.495109] PM: resume of devices > complete after 3641.933 msecs > However, even when patch was not present(and it passed), there is a logical > disconnection of devices, so you would face the issue mentioned in > https://bugzilla.kernel.org/show_bug.cgi?id=53211. > > Looking to the timeout, it seems that wait loop went for full length > (2S) for all the devices, still could not find a connected device. So, > basically SS link between root hub and hub was not up in 2 sec. Not > sure why, but reading further hub port status caused some fatal issue > with xhci host and so it is not able to get new device connection > after logical disconnection. > > Increasing the timeout value may help. But with this long timeout I see a > possibility of sync issue between port_event and usb_port_resume. It > might happen that port_event reads hub port status before > usb_port_resume handles reset_resume. > > Can you try following patch with step increasing varied value of > PORT_ENABLE_WAIT, and then let me know which value of > PORT_ENABLE_WAIT works for you (if it works ;)). > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index 11e80ac31324..6eaf481d3d53 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -3311,13 +3311,14 @@ static int finish_port_resume(struct usb_device *udev) > * This routine should only be called when persist is enabled for a SS > * device. > */ > +#define PORT_ENABLE_WAIT 2000 > static int wait_for_ss_port_enable(struct usb_device *udev, > struct usb_hub *hub, int *port1, > u16 *portchange, u16 *portstatus) > { > int status = 0, delay_ms = 0; > > - while (delay_ms < 2000) { > + while (delay_ms < PORT_ENABLE_WAIT) { > if (status || *portstatus & USB_PORT_STAT_CONNECTION) > break; > msleep(20); > @@ -4881,6 +4882,22 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, > usb_lock_port(port_dev); > } > > +static void wait_for_reset_resume(struct usb_hub *hub, int port) > +{ > + struct usb_device *udev; > + int delay_ms = 0; > + > + udev = hub->ports[port -1]->child; > + if (udev && udev->reset_resume) { > + while (delay_ms < PORT_ENABLE_WAIT) { > + if (!udev->reset_resume) > + break; > + msleep(20); > + delay_ms += 20; > + } > + } > +} > + > static void port_event(struct usb_hub *hub, int port1) > __must_hold(&port_dev->status_lock) > { > @@ -4894,6 +4911,8 @@ static void port_event(struct usb_hub *hub, int port1) > clear_bit(port1, hub->event_bits); > clear_bit(port1, hub->wakeup_bits); > > + wait_for_reset_resume(hub, port1); > + > if (hub_port_status(hub, port1, &portstatus, &portchange) < 0) > return; > > Regards > Pratyush Thanks for the feedback, Pratyush. We'll test your patch and get back to you. > >> -- dmesg log with following additional debug print. >> @@ -3318,6 +3318,7 @@ static int wait_for_ss_port_enable(struct usb_device *udev, >> int status = 0, delay_ms = 0; >> >> while (delay_ms < 2000) { >> + printk("%s:portstatus is %x and portchange is %x\n", __func__, *portstatus, *portchange); >> if (status || *portstatus & USB_PORT_STAT_CONNECTION) >> break; >> >>> or would it be best to submit a revert request? >> Let me see what is the portstatus value and why didn't it break loop in first >> iteration if device was OK. >> >> Regards >> Pratyush >> >>> >>> >>> Thanks, >>> >>> Joe >>> >>> [0] http://pad.lv/1384041 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
