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Subject[RFC/PATCH 2/2] usb: ffs/dwc3: pad epout buffer size when not aligned to maxpacketsize
Date
DWC3 requires buffer size to be aligned to maxpacketsize of an out
endpoint. ffs_epfile_io() needs to pad epout buffer to match above
condition if DWC3 controller is used.

This patch solves an specific situation but a more generic solution
should be found.

Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
---
drivers/usb/gadget/f_fs.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 75e4b78..33880e6 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -27,6 +27,7 @@
#include <linux/usb/composite.h>
#include <linux/usb/functionfs.h>

+#include "gadget_chips.h"

#define FUNCTIONFS_MAGIC 0xa647361 /* Chosen by a honest dice roll ;) */

@@ -755,10 +756,12 @@ static ssize_t ffs_epfile_io(struct file *file,
char __user *buf, size_t len, int read)
{
struct ffs_epfile *epfile = file->private_data;
+ struct usb_gadget *gadget = epfile->ffs->gadget;
struct ffs_ep *ep;
char *data = NULL;
ssize_t ret;
int halt;
+ size_t orig_len = len;

goto first_try;
do {
@@ -794,6 +797,22 @@ first_try:
goto error;
}

+ /*
+ * DWC3 requires buffer size to be aligned to maxpacketsize
+ * of an out endpoint.
+ * FIXME: a more generic solution might be necessary.
+ */
+ if (gadget_is_dwc3(gadget) && read &&
+ !IS_ALIGNED(len, ep->ep->desc->wMaxPacketSize)) {
+ size_t old_len = len;
+ len = roundup(orig_len,
+ (size_t)ep->ep->desc->wMaxPacketSize);
+ if (unlikely(data) && len > old_len) {
+ kfree(data);
+ data = NULL;
+ }
+ }
+
/* Allocate & copy */
if (!halt && !data) {
data = kzalloc(len, GFP_KERNEL);
--
1.8.4.rc3


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