Re: [U-Boot] [PATCH] fastboot: Fix OUT transaction length alignment

On Wed, Apr 13, 2016 at 3:01 PM, Semen Protsenko semen.protsenko@linaro.org wrote:

From: Sam Protsenko semen.protsenko@linaro.org

Some UDC controllers may require buffer size to be aligned to wMaxPacketSize. It's indicated by gadget->quirk_ep_out_aligned_size field being set to "true" (in UDC driver code). In that case rx_bytes_expected must be aligned to wMaxPacket size, otherwise stuck on transaction will happen. For example, it's required by DWC3 controller data manual:

section 8.2.3.3 Buffer Size Rules and Zero-Length Packets:

For OUT endpoints, the following rules apply:
- The BUFSIZ field must be ≥ 1 byte.
- The total size of a Buffer Descriptor must be a multiple of
  MaxPacketSize
- A received zero-length packet still requires a MaxPacketSize buffer.
  Therefore, if the expected amount of data to be received is a multiple
  of MaxPacketSize, software should add MaxPacketSize bytes to the buffer
  to sink a possible zero-length packet at the end of the transfer.

But other UDC controllers don't need such alignment, so mentioned field is set to "false". If buffer size is aligned to wMaxPacketSize, those controllers may stuck on transaction. The example is DWC2.

This patch checks gadget->quirk_ep_out_aligned_size field and aligns rx_bytes_expected to wMaxPacketSize only when it's needed.

Signed-off-by: Sam Protsenko semen.protsenko@linaro.org

drivers/usb/gadget/f_fastboot.c | 9 +++++++++ 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/gadget/f_fastboot.c b/drivers/usb/gadget/f_fastboot.c index 2e87fee..54dcce0 100644 --- a/drivers/usb/gadget/f_fastboot.c +++ b/drivers/usb/gadget/f_fastboot.c @@ -58,6 +58,7 @@ static unsigned int fastboot_flash_session_id; static unsigned int download_size; static unsigned int download_bytes; static bool is_high_speed; +static bool quirk_ep_out_aligned_size;

static struct usb_endpoint_descriptor fs_ep_in = { .bLength = USB_DT_ENDPOINT_SIZE, @@ -240,6 +241,8 @@ static int fastboot_set_alt(struct usb_function *f, debug("%s: func: %s intf: %d alt: %d\n", __func__, f->name, interface, alt);

•   quirk_ep_out_aligned_size = gadget->quirk_ep_out_aligned_size;
  

•   /* make sure we don't enable the ep twice */
    if (gadget->speed == USB_SPEED_HIGH) {
            ret = usb_ep_enable(f_fb->out_ep, &hs_ep_out);
  

@@ -435,12 +438,18 @@ static unsigned int rx_bytes_expected(unsigned int maxpacket) return 0; if (rx_remain > EP_BUFFER_SIZE) return EP_BUFFER_SIZE;

•   if (!quirk_ep_out_aligned_size)
  

•           goto out;
  

•   if (rx_remain < maxpacket) {
            rx_remain = maxpacket;
    } else if (rx_remain % maxpacket != 0) {
            rem = rx_remain % maxpacket;
            rx_remain = rx_remain + (maxpacket - rem);
    }
  

+out: return rx_remain; }

-- 2.8.0.rc3

Steve,

Can you please check if it fixes "fastboot flash" on your boards?

Thanks.