From mboxrd@z Thu Jan 1 00:00:00 1970 From: stefan.wahren@i2se.com (Stefan Wahren) Date: Tue, 18 Apr 2017 22:25:06 +0200 (CEST) Subject: usb: dwc2: NMI watchdog: BUG: soft lockup - CPU#0 stuck for 146s In-Reply-To: <79b9b35b-0600-771f-4cd2-9e03c5ba3a25@i2se.com> References: <1795308650.27171.9a53158f-312d-40ce-80ce-8bf792d8db34.open-xchange@email.1und1.de> <172093673.40121.1492427140661@email.1und1.de> <79b9b35b-0600-771f-4cd2-9e03c5ba3a25@i2se.com> Message-ID: <186569458.91967.1492547106553@email.1und1.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, [add Johan] > Stefan Wahren hat am 18. April 2017 um 10:07 geschrieben: > > > Am 18.04.2017 um 00:37 schrieb Doug Anderson: > > Hi, > > > > On Mon, Apr 17, 2017 at 4:05 AM, Stefan Wahren wrote: > >> Hi, > >> > >>> Stefan Wahren hat am 31. Oktober 2016 um 21:34 geschrieben: > >>> > >>> > >>> I inspired by this issue [1] i build up a slightly modified setup with a > >>> Raspberry Pi B (mainline kernel 4.9rc3), a powered 7 port USB hub and 5 Prolific > >>> PL2303 USB to serial convertors. I modified the usb_test for dwc2 [2], which > >>> only tries to open all ttyUSB devices one after the other. > >>> > >>> Unfortunately the complete system stuck after opening the first ttyUSB device ( > >>> heartbeat LED stop blinking, no reaction to debug UART). The only way to > >>> reanimate the system is to powerdown the USB hub with the USB to serial > >>> convertors. > >>> > >>> [1] - https://github.com/raspberrypi/linux/issues/1692 > >>> [2] - https://gist.github.com/lategoodbye/dd0d30af27b6f101b03d5923b279dbaa > >> since this issue still exists with 4.11 (even without or with microframe scheduler enabled), i want to ask some additional questions: > >> > >> Is this issue reproducible with other dwc2 platforms than bcm2835? > > +Edmund Szeto, who I seem to remember emailing me about similar > > questions in the past. > > > > > >> Does the soft lockup also occurs after opening the second serial convertor or later? > > I don't have serial converters easily available to me, but back in the > > day when I was stressing things out on rk3288 I never saw anything > > this bad. ...of course, on rk3288 we've got 4 A17 cores running > > really fast, so possibly just being slower is what causes your > > problems here? > > The downstream kernel of the Raspberry Pi foundation with it's > out-of-tree dwc_otg driver is able to handle 8 serial converter on a RPI > B. I would be happy to get at least 2 or 3 working on mainline. > > > > > I will make the following observations: > > > > 1. With dwc2 you often end up in the situation where you need to > > service an interrupt every 125 uS. If servicing that interrupt takes > > anywhere near 125 uS in the common case then you'll be in trouble. > > I will try to measure this with a logic analyzer. > i took GPIO17 to measure _dwc2_hcd_irq and GPIO18 to measure _dwc2_hcd_urb_enqueue (patch against 4.11rc1 below). So i made my observations for 3 test cases: 1) no serial converter connected (idle) 2) 1 FTDI serial converter connected 3) 1 PL2303 serial converter connected case | ksoftirq cpu | mean duration | max duration | max duration | urb_enqueue | | | hcd_irq | hcd_irq | urb_enqueue | within 10 sec| -------+------------------+---------------+---------------+--------------+--------------+ idle | 0.0% | 2 us | 16.5 us | 12 us | 5 | FTDI | 25.0% | 8.5 us | 18.0 us | 31000 us | ~ 400 | PL2303 | top doesn't work | 8.5 us | 22.5 us | 900000 us | 4 | So it seems the serial USB driver has also an impact. In the analyzer trace the FTDI triggers many smaller urb_enqueue calls in the opposite to the PL2303 which only has few but huge calls. Additional notes: After closing the serial connection to the FTDI the system is usable as before. In case of PL2303 i need to disconnect the converter in order to get a usable system. Why do they behave so differently? Are these results of a overload? Doug, can you point me to your timing patch? Thanks Stefan PS: My hacky patches for measuring diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h index 1a7e830..aa490c3 100644 --- a/drivers/usb/dwc2/core.h +++ b/drivers/usb/dwc2/core.h @@ -930,6 +930,9 @@ struct dwc2_hsotg { struct dentry *debug_root; struct debugfs_regset32 *regset; + int gpio_17; + int gpio_18; + /* DWC OTG HW Release versions */ #define DWC2_CORE_REV_2_71a 0x4f54271a #define DWC2_CORE_REV_2_90a 0x4f54290a diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c index a73722e..97271c8 100644 --- a/drivers/usb/dwc2/hcd.c +++ b/drivers/usb/dwc2/hcd.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include #include @@ -4595,13 +4596,17 @@ static int _dwc2_hcd_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, bool qh_allocated = false; struct dwc2_qtd *qtd; + gpio_set_value(hsotg->gpio_18, 1); + if (dbg_urb(urb)) { dev_vdbg(hsotg->dev, "DWC OTG HCD URB Enqueue\n"); dwc2_dump_urb_info(hcd, urb, "urb_enqueue"); } - if (!ep) + if (!ep) { + gpio_set_value(hsotg->gpio_18, 0); return -EINVAL; + } if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS || usb_pipetype(urb->pipe) == PIPE_INTERRUPT) { @@ -4628,8 +4633,10 @@ static int _dwc2_hcd_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, dwc2_urb = dwc2_hcd_urb_alloc(hsotg, urb->number_of_packets, mem_flags); - if (!dwc2_urb) + if (!dwc2_urb) { + gpio_set_value(hsotg->gpio_18, 0); return -ENOMEM; + } dwc2_hcd_urb_set_pipeinfo(hsotg, dwc2_urb, usb_pipedevice(urb->pipe), usb_pipeendpoint(urb->pipe), ep_type, @@ -4705,6 +4712,8 @@ static int _dwc2_hcd_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, spin_unlock_irqrestore(&hsotg->lock, flags); + gpio_set_value(hsotg->gpio_18, 0); + return 0; fail3: @@ -4732,6 +4741,8 @@ static int _dwc2_hcd_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, fail0: kfree(dwc2_urb); + gpio_set_value(hsotg->gpio_18, 0); + return retval; } @@ -4825,8 +4836,15 @@ static void _dwc2_hcd_endpoint_reset(struct usb_hcd *hcd, static irqreturn_t _dwc2_hcd_irq(struct usb_hcd *hcd) { struct dwc2_hsotg *hsotg = dwc2_hcd_to_hsotg(hcd); + irqreturn_t ret; - return dwc2_handle_hcd_intr(hsotg); + gpio_set_value(hsotg->gpio_17, 1); + + ret = dwc2_handle_hcd_intr(hsotg); + + gpio_set_value(hsotg->gpio_17, 0); + + return ret; } /* diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c index 9564bc7..e3f8a8a 100644 --- a/drivers/usb/dwc2/platform.c +++ b/drivers/usb/dwc2/platform.c @@ -35,6 +35,7 @@ */ #include +#include #include #include #include @@ -404,6 +405,16 @@ static int dwc2_driver_probe(struct platform_device *dev) return hsotg->irq; } + hsotg->gpio_17 = 475; + retval = devm_gpio_request_one(hsotg->dev, hsotg->gpio_17, GPIOF_OUT_INIT_LOW, "gpio_17"); + if (retval) + pr_warn("Unable to request GPIO17: %d\n", retval); + + hsotg->gpio_18 = 476; + retval = devm_gpio_request_one(hsotg->dev, hsotg->gpio_18, GPIOF_OUT_INIT_LOW, "gpio_18"); + if (retval) + pr_warn("Unable to request GPIO18: %d\n", retval); + dev_dbg(hsotg->dev, "registering common handler for irq%d\n", hsotg->irq); retval = devm_request_irq(hsotg->dev, hsotg->irq,