On Sat, Jun 24, 2023, Krishna Kurapati PSSNV wrote:
>
>
> On 6/24/2023 3:57 AM, Thinh Nguyen wrote:
> > On Wed, Jun 21, 2023, Krishna Kurapati wrote:
> > > On some SoC's like SA8295P where the tertiary controller is host-only
> > > capable, GEVTADDRHI/LO, GEVTSIZ, GEVTCOUNT registers are not accessible.
> > > Trying to access them leads to a crash.
> > >
> > > For DRD/Peripheral supported controllers, event buffer setup is done
> > > again in gadget_pullup. Skip setup or cleanup of event buffers if
> > > controller is host-only capable.
> > >
> > > Suggested-by: Johan Hovold <johan@xxxxxxxxxx>
> > > Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
> > > ---
> > > drivers/usb/dwc3/core.c | 11 +++++++++++
> > > 1 file changed, 11 insertions(+)
> > >
> > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > > index 32ec05fc242b..e1ebae54454f 100644
> > > --- a/drivers/usb/dwc3/core.c
> > > +++ b/drivers/usb/dwc3/core.c
> > > @@ -486,6 +486,11 @@ static void dwc3_free_event_buffers(struct dwc3 *dwc)
> > > static int dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned int length)
> > > {
> > > struct dwc3_event_buffer *evt;
> > > + unsigned int hw_mode;
> > > +
> > > + hw_mode = DWC3_GHWPARAMS0_MODE(dwc->hwparams.hwparams0);
> > > + if (hw_mode == DWC3_GHWPARAMS0_MODE_HOST)
> > > + return 0;
> >
> > This is a little awkward. Returning 0 here indicates that this function
> > was successful, and the event buffers were allocated based on the
> > function name. Do this check outside of dwc3_alloc_one_event_buffer()
> > and specifically set dwc->ev_buf = NULL if that's the case.
> >
> Hi Thinh,
>
> Apologies, I didn't understand the comment properly.
>
> I thought we were supposed to return 0 here if we fulfill the goal of this
> function (allocate if we are drd/gadget and don't allocate if we are host
> mode only).
The name of the function implies that it returns 0 if it allocated the
event buffer. If there are multiple conditions to the function returning
0 here, then we should document it.
>
> If we return a non zero error here, probe would fail as this call will be
> done only for host only controllers during probe and nowhere else.
>
> Are you suggesting we move this check to dwc3_alloc_one_event_buffer call
> ?
>
> Regards,
> Krishna,
>
I'm suggesting to move the check to the caller of
dwc3_alloc_one_event_buffer(). Something like this so that it's
self-documented:
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 0beaab932e7d..bba82792bf6f 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1773,6 +1773,7 @@ static int dwc3_probe(struct platform_device *pdev)
struct resource *res, dwc_res;
void __iomem *regs;
struct dwc3 *dwc;
+ unsigned int hw_mode;
int ret;
dwc = devm_kzalloc(dev, sizeof(*dwc), GFP_KERNEL);
@@ -1854,11 +1855,16 @@ static int dwc3_probe(struct platform_device *pdev)
pm_runtime_forbid(dev);
- ret = dwc3_alloc_event_buffers(dwc, DWC3_EVENT_BUFFERS_SIZE);
- if (ret) {
- dev_err(dwc->dev, "failed to allocate event buffers\n");
- ret = -ENOMEM;
- goto err_allow_rpm;
+ hw_mode = DWC3_GHWPARAMS0_MODE(dwc->hwparams.hwparams0);
+ if (hw_mode == DWC3_GHWPARAMS0_MODE_HOST) {
+ dwc->ev_buf = NULL;
+ } else {
+ ret = dwc3_alloc_event_buffers(dwc, DWC3_EVENT_BUFFERS_SIZE);
+ if (ret) {
+ dev_err(dwc->dev, "failed to allocate event buffers\n");
+ ret = -ENOMEM;
+ goto err_allow_rpm;
+ }
}
dwc->edev = dwc3_get_extcon(dwc);
--
Thanks,
Thinh
