Re: [PATCH] usb/dwc3: Correct cache sync issue in case of ep0 bounced

[Pratyush Anand]

On 8/10/2012 1:07 PM, Felipe Balbi wrote:

Hi,

On Fri, Aug 10, 2012 at 12:54:52PM +0530, Pratyush Anand wrote:

In case of ep0 out, if length is not aligned to maxpacket size then we
use dwc->ep_bounce_addr for dma transfer and not request->dma. Since, we
have alreday done memcpy from dwc->ep_bounce to request->buf, so we do
not need to issue cache sync function. Infact, cache sync function will
bring wrong data in request->buf from request->dma in this scenario.

So, cache sync function must not be executed in case of ep0 bounced.

Signed-off-by: Pratyush Anand <pratyush.an...@st.com>

this is very nice fix, but ...

---
  drivers/usb/dwc3/ep0.c    |    1 -
  drivers/usb/dwc3/gadget.c |    7 +++++--
  2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 7b99c5a..1e88de8 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -804,7 +804,6 @@ static void dwc3_ep0_complete_data(struct dwc3 *dwc,
                transferred = min_t(u32, ur->length,
                                transfer_size - length);
                memcpy(ur->buf, dwc->ep0_bounce, transferred);
-               dwc->ep0_bounced = false;
        } else {
                transferred = ur->length - length;
        }
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 800944f..4205a6c 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -263,8 +263,11 @@ void dwc3_gadget_giveback(struct dwc3_ep *dep, struct 
dwc3_request *req,
        if (req->request.status == -EINPROGRESS)
                req->request.status = status;

-       usb_gadget_unmap_request(&dwc->gadget, &req->request,
-                       req->direction);
+       if (!dwc->ep0_bounced)
+               usb_gadget_unmap_request(&dwc->gadget, &req->request,
+                               req->direction);
+       else
+               dwc->ep0_bounced = false;

I'm not sure this will work always, though. What if we have unaligned
ep0 out PLUS some started transfers on non-ep0/1 and those complete
before the unaligned ep0out transfer ?

Yes , I think you are correct. In such scenario it might fail.

You will be preventing cache sync on the non-ep0out transfer. I think
you need to check for ep0, something like:

if ((dep->number == 0 && !dwc->ep0_bounced) ||
        dep->number > 0)
        usb_gadget_unmap_request();
else
        dwc->ep0_bounced = false;

or something similar.

if (dep->number == 0 && dwc->ep0_bounced)
        dwc->ep0_bounced = false;
else
        usb_gadget_unmap_request();

would be fine.

Regards
Pratyush


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