On 11/11/2013 03:55 PM, Michal Nazarewicz wrote:
On Mon, Nov 11 2013, David Cohen wrote:
Due to USB controllers may have different restrictions, usb gadget layer
needs to provide a generic way to inform gadget functions to complain
with non-standard requirements.
This patch adds 'quirk_ep_out_aligned_size' field to struct usb_gadget
to inform when controller's epout requires buffer size to be aligned to
MaxPacketSize. A helper is also provided to align buffer size when
necessary.
Signed-off-by: David Cohen <david.a.cohen@xxxxxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
---
Michal,
I added prefix 'usb: f_fs: ' to patch's subject. I did not add 'usb: gadget:
f_fs' due to it would be too long.
include/linux/usb/gadget.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 23b3bfd0a842..41e8834af57d 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -441,6 +441,19 @@ static inline void usb_ep_fifo_flush(struct usb_ep *ep)
ep->ops->fifo_flush(ep);
}
+/**
+ * usb_ep_align_maxpacketsize - returns @len aligned to ep's maxpacketsize
+ * @ep: the endpoint whose maxpacketsize is used to align @len
+ * @len: buffer size's length to align to @ep's maxpacketsize
+ *
+ * This helper is used in case it's required for any reason to align buffer's
+ * size to an ep's maxpacketsize.
+ */
+static inline size_t usb_ep_align_maxpacketsize(struct usb_ep *ep, size_t len)
+{
+ return round_up(len, (size_t)ep->desc->wMaxPacketSize);
+}
+
Come to think of it, perhaps even better helper would be:
static inline size_t usb_ep_align_maybe(
struct usb_gadget *gadget, struct usb_ep *ep, size_t len) {
return gadget->quir_ep_out_aligned_size ?
round_up(len, (size_t)ep->desc->wMaxPacketSize) : len;
}
The CPU time to check unsigned:1 and possibly jump is about the same as
round_up() itself. For readability matters, we can round_up() directly.
Br, David
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