[U-Boot] [PATCH] usb_storage: fix ehci driver max transfer size

[Stefan Herbrechtsmeier]

The commit 5dd95cf93dfffa1d19a1928990852aac9f55b9d9 'usb_storage:
Fix EHCI "out of buffer pointers" with CD-ROM' introduce a bug in
usb_storage as it wrongly assumes that every transfer can use 4k
per qt_buffer. This is wrong if the start address of the data
is not 4k aligned and leads to 'EHCI timed out on TD' messages
because of 'out of buffer pointers' in ehci_td_buffer function.

Cc: Marek Vasut <marex at denx.de>
Signed-off-by: Stefan Herbrechtsmeier <stefan at herbrechtsmeier.net>
---
 common/usb_storage.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/common/usb_storage.c b/common/usb_storage.c
index faad237..612a553 100644
--- a/common/usb_storage.c
+++ b/common/usb_storage.c
@@ -1416,10 +1416,10 @@ int usb_stor_get_info(struct usb_device *dev, struct us_data *ss,
 	USB_STOR_PRINTF("partype: %d\n", dev_desc->part_type);
 
 	/*
-	 * The U-Boot EHCI driver cannot handle more than 4096 * 5 bytes in a
-	 * transfer without running itself out of qt_buffers.
+	 * The U-Boot EHCI driver cannot handle more than 4096 * 4 bytes in a
+	 * unaligned transfer without running itself out of qt_buffers.
 	 */
-	ss->max_xfer_blk = (4096 * 5) / dev_desc->blksz;
+	ss->max_xfer_blk = (4096 * 4) / dev_desc->blksz;
 
 	init_part(dev_desc);
 
-- 
1.7.9.5