[PATCH] usb: gadget: f_midi: Fixing wMaxPacketSize exceeded issue during MIDI bind retries

Selvarasu Ganesan
2024-12-08T15:23:43Z

The current implementation sets the wMaxPacketSize of bulk in/out
endpoints to 1024 bytes at the end of the f_midi_bind function. However,
in cases where there is a failure in the first midi bind attempt,
consider rebinding. This scenario may encounter an f_midi_bind issue due
to the previous bind setting the bulk endpoint's wMaxPacketSize to 1024
bytes, which exceeds the ep->maxpacket_limit where configured TX/RX
FIFO's maxpacket size of 512 bytes for IN/OUT endpoints in support HS
speed only.
This commit addresses this issue by resetting the wMaxPacketSize before
endpoint claim.

Fixes: 46decc82ffd5 ("usb: gadget: unconditionally allocate hs/ss descriptor in bind operation")
Cc: stable@vger.kernel.org
Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
---
drivers/usb/gadget/function/f_midi.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 837fcdfa3840..5caa0e4eb07e 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -907,6 +907,15 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)

status = -ENODEV;

+ /*
+ * Reset wMaxPacketSize with maximum packet size of FS bulk transfer before
+ * endpoint claim. This ensures that the wMaxPacketSize does not exceed the
+ * limit during bind retries where configured TX/RX FIFO's maxpacket size
+ * of 512 bytes for IN/OUT endpoints in support HS speed only.
+ */
+ bulk_in_desc.wMaxPacketSize = cpu_to_le16(64);
+ bulk_out_desc.wMaxPacketSize = cpu_to_le16(64);
+
/* allocate instance-specific endpoints */
midi->in_ep = usb_ep_autoconfig(cdev->gadget, &bulk_in_desc);
if (!midi->in_ep)
--
2.17.1