According to Synopsys Programming Guide chapter 2.2 Register Resets,
it cannot reset the DCTL register by setting DCTL.CSFTRST for core soft
reset, if DWC3 controller as a slave device and stay connected with a usb
host, then, while rebooting linux, it will fail to reinitialize dwc3 as a
slave device when the DWC3 controller did not power off. because the
connection status is incorrect, so we also need to clear DCTL.RUN_STOP
bit for disabling connect when doing core soft reset.
Fixes: f59dcab176293b6 ("usb: dwc3: core: improve reset sequence")
Signed-off-by: Dejin Zheng <[email protected]>
---
v1 -> v2:
* modify some commit messages by Sergei's suggest, Thanks
very much for Sergei's help!
drivers/usb/dwc3/core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 2eb34c8b4065..239636c454c2 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -256,6 +256,7 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
reg = dwc3_readl(dwc->regs, DWC3_DCTL);
reg |= DWC3_DCTL_CSFTRST;
+ reg &= ~DWC3_DCTL_RUN_STOP;
dwc3_writel(dwc->regs, DWC3_DCTL, reg);
/*
--
2.25.0
Dejin Zheng wrote:
> According to Synopsys Programming Guide chapter 2.2 Register Resets,
> it cannot reset the DCTL register by setting DCTL.CSFTRST for core soft
> reset, if DWC3 controller as a slave device and stay connected with a usb
> host, then, while rebooting linux, it will fail to reinitialize dwc3 as a
> slave device when the DWC3 controller did not power off.
If you reboot the OS, wouldn't it go through the driver tear-down
sequence and clear the run_stop bit anyway?
However, I can see how this can be an issue.
> because the
> connection status is incorrect, so we also need to clear DCTL.RUN_STOP
> bit for disabling connect when doing core soft reset.
>
> Fixes: f59dcab176293b6 ("usb: dwc3: core: improve reset sequence")
> Signed-off-by: Dejin Zheng <[email protected]>
> ---
> v1 -> v2:
> * modify some commit messages by Sergei's suggest, Thanks
> very much for Sergei's help!
>
> drivers/usb/dwc3/core.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 2eb34c8b4065..239636c454c2 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -256,6 +256,7 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
>
> reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> reg |= DWC3_DCTL_CSFTRST;
> + reg &= ~DWC3_DCTL_RUN_STOP;
> dwc3_writel(dwc->regs, DWC3_DCTL, reg);
>
> /*
There will still be other stale configuration in DCTL if you do this. I
think it's better to reset the other fields of DCTL to the default
(should be all 0s) instead of doing register read-modify-write as what
we're doing here. If not, at least we should use
dwc3_gadget_dctl_write_safe().
Thanks,
Thinh
On Mon, Oct 19, 2020 at 10:04:41PM +0000, Thinh Nguyen wrote:
> Dejin Zheng wrote:
Hi Thinh:
> > According to Synopsys Programming Guide chapter 2.2 Register Resets,
> > it cannot reset the DCTL register by setting DCTL.CSFTRST for core soft
> > reset, if DWC3 controller as a slave device and stay connected with a usb
> > host, then, while rebooting linux, it will fail to reinitialize dwc3 as a
> > slave device when the DWC3 controller did not power off.
>
> If you reboot the OS, wouldn't it go through the driver tear-down
> sequence and clear the run_stop bit anyway?
Yes, you are right, this is a point worth checking. and I think it might
still be necessary to reset it.
> However, I can see how this can be an issue.
>
> > because the
> > connection status is incorrect, so we also need to clear DCTL.RUN_STOP
> > bit for disabling connect when doing core soft reset.
> >
> > Fixes: f59dcab176293b6 ("usb: dwc3: core: improve reset sequence")
> > Signed-off-by: Dejin Zheng <[email protected]>
> > ---
> > v1 -> v2:
> > * modify some commit messages by Sergei's suggest, Thanks
> > very much for Sergei's help!
> >
> > drivers/usb/dwc3/core.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index 2eb34c8b4065..239636c454c2 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -256,6 +256,7 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
> >
> > reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> > reg |= DWC3_DCTL_CSFTRST;
> > + reg &= ~DWC3_DCTL_RUN_STOP;
> > dwc3_writel(dwc->regs, DWC3_DCTL, reg);
> >
> > /*
>
> There will still be other stale configuration in DCTL if you do this. I
> think it's better to reset the other fields of DCTL to the default
> (should be all 0s) instead of doing register read-modify-write as what
> we're doing here. If not, at least we should use
> dwc3_gadget_dctl_write_safe().
>
Thinh, thanks very much for your suggestion, I think it might be better
to reset all areas of DCTL register. I tested it on my SOC platform and
it worked.
BR,
Dejin
> Thanks,
> Thinh
>