Re: [PATCH v8 4/9] usb: dwc3: core: Skip setting event buffers for host only controllers

[Krishna Kurapati PSSNV]

On 5/16/2023 5:47 PM, Johan Hovold wrote:
> On Sun, May 14, 2023 at 11:19:12AM +0530, 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 setup them up during core_init 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.
> >
> > Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
> > ---
> >   drivers/usb/dwc3/core.c | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index e983aef1fb93..46192d08d1b6 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -505,6 +505,11 @@ static int dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned int length)
> >   int dwc3_event_buffers_setup(struct dwc3 *dwc)
> >   {
> >   	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;
> >   
> >   	evt = dwc->ev_buf;
>
> How about adding this check to dwc3_alloc_event_buffers() instead as
> there should be no need to allocate buffer that you never use?
>
> Then you can just check dwc->ev_buf here and elsewhere.

Thanks for this idea. We can save 4096 bytes from being allocated this 
way. Will get this in next version.

Regards,
Krishna,