Roger Quadros <rogerq@xxxxxx> writes:
> [ text/plain ]
> The existing workaround of forcing DEVSPD to SUPER_SPEED
> for HIGH_SPEED ports is causing another side effect
> which causes erratic interrupts and delayed gadget
> enumeration of upto 2 seconds.
>
> Work around the run/stop issue by detecting if
> it happened using debug LTSSM state and issuing
> soft reset to the device controller when changing RUN_STOP
> from 0 to 1.
>
> We apply the workaround only if PRTCAP is DEVICE mode
> as we don't yet support this workaround in OTG mode.
>
> Use USB RESET event as exit condition for workaround.
>
> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> ---
> drivers/usb/dwc3/core.h | 1 +
> drivers/usb/dwc3/gadget.c | 175 +++++++++++++++++++++++++++++++++++++---------
> 2 files changed, 144 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 2bea1ac..a724c0d 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -762,6 +762,7 @@ struct dwc3 {
>
> struct usb_gadget gadget;
> struct usb_gadget_driver *gadget_driver;
> + struct completion reset_event; /* used for run/stop workaround */
the fact that you needed a struct completion here already points to the
fact this is really, really bad :-)
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 3ac170f..03418b8 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -35,6 +35,9 @@
> #include "gadget.h"
> #include "io.h"
>
> +static void dwc3_gadget_disable_irq(struct dwc3 *dwc);
> +static int dwc3_gadget_restart(struct dwc3 *dwc);
> +
> /**
> * dwc3_gadget_set_test_mode - Enables USB2 Test Modes
> * @dwc: pointer to our context structure
> @@ -1570,13 +1573,100 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
> struct dwc3 *dwc = gadget_to_dwc(g);
> unsigned long flags;
> int ret;
> + int trys = 0;
>
> is_on = !!is_on;
>
> + if (is_on)
> + reinit_completion(&dwc->reset_event);
> +
> spin_lock_irqsave(&dwc->lock, flags);
> ret = dwc3_gadget_run_stop(dwc, is_on, false);
> spin_unlock_irqrestore(&dwc->lock, flags);
>
> +try:
> + /**
> + * WORKAROUND: DWC3 revision < 2.20a have an issue
> + * which would cause metastability state on Run/Stop
> + * bit if we try to force the IP to USB2-only mode.
> + *
> + * Because of that, we check if we hit that issue and
> + * reset core and retry if we did.
> + *
> + * We only attempt this workaround if we are in
> + * DEVICE mode (i.e. not OTG).
> + *
> + * Refers to:
> + *
> + * STAR#9000525659: Clock Domain Crossing on DCTL in
> + * USB 2.0 Mode
> + */
> + if (is_on && dwc->revision < DWC3_REVISION_220A &&
> + dwc->prtcap_mode == DWC3_GCTL_PRTCAP_DEVICE) {
> + u32 devspd, ltssm;
> + unsigned long t;
> +
> + /* only applicable if devspd != SUPERSPEED */
> + devspd = dwc3_readl(dwc->regs, DWC3_DCFG) & DWC3_DCFG_SPEED_MASK;
> + if (devspd == DWC3_DCFG_SUPERSPEED)
> + goto done;
> +
> + /* get link state */
> + ltssm = dwc3_readl(dwc->regs, DWC3_GDBGLTSSM);
> + ltssm = (ltssm >> 22) & 0xf;
> +
> + /**
> + * Need to wait for 100ms and check if ltssm != 4 to detect
> + * metastability issue. If we got a reset event then we are
> + * safe and can continue.
> + */
> + t = wait_for_completion_timeout(&dwc->reset_event,
> + msecs_to_jiffies(100));
> + if (t)
> + goto done;
> +
> + /**
> + * If link state != 4 we've hit the metastability issue, soft reset.
> + */
> + if (ltssm == 4)
> + goto done;
> +
> + dwc3_trace(trace_dwc3_gadget,
> + "applying metastability workaround\n");
> + trys++;
> + if (trys == 2) {
> + dev_WARN_ONCE(dwc->dev, true,
> + "metastability workaround failed!\n");
> + return -ETIMEDOUT;
> + }
> +
> + spin_lock_irqsave(&dwc->lock, flags);
> + /* stop gadget */
> + dwc3_gadget_disable_irq(dwc);
> + __dwc3_gadget_ep_disable(dwc->eps[0]);
> + __dwc3_gadget_ep_disable(dwc->eps[1]);
> +
> + /* soft reset device and restart */
> + ret = dwc3_device_reinit(dwc);
> + if (ret) {
> + dev_err(dwc->dev, "device reinit failed\n");
> + return ret;
> + }
> +
> + reinit_completion(&dwc->reset_event);
> + /* restart gadget */
> + ret = dwc3_gadget_restart(dwc);
> + if (ret) {
> + dev_err(dwc->dev, "failed to re-init gadget\n");
> + return ret;
> + }
> +
> + spin_unlock_irqrestore(&dwc->lock, flags);
> + goto try;
> + }
holy crap dude ?!? Now ->pullup() has to reinitialize dwc3 completely ?
--
balbi
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