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

On 5/16/2023 5:47 PM, Johan Hovold wrote:

On Sun, May 14, 2023 at 11:19:12AM +0530, Krishna Kurapati wrote:

quoted

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 <redacted>
---
  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,