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[v2,3/3] usb: gadgetfs: return USB_GADGET_DELAYED_STATUS from setup()

Message ID a8d2b91f9890dc21daa359183e84879ff4525180.1693237258.git.andreyknvl@gmail.com
State New
Headers show
Series [v2,1/3] usb: gadget: clarify usage of USB_GADGET_DELAYED_STATUS | expand

Commit Message

andrey.konovalov@linux.dev Aug. 28, 2023, 3:43 p.m. UTC 
From: Andrey Konovalov <andreyknvl@gmail.com>

Return USB_GADGET_DELAYED_STATUS from the setup() callback for 0-length
transfers as a workaround to stop some UDC drivers (e.g. dwc3) from
automatically proceeding with the status stage.

This workaround should be removed once all UDC drivers are fixed to
always delay the status stage until a response is queued to EP0.

Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>

---

Changes v1->v2:
- Added comment for composite.h include as suggested by Alan.
- Moved undefs next to composite.h include as suggested by Alan.
---
 drivers/usb/gadget/legacy/inode.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index 28249d0bf062..e71cd591cda1 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -31,6 +31,12 @@ 
 
 #include <linux/usb/gadgetfs.h>
 #include <linux/usb/gadget.h>
+#include <linux/usb/composite.h> /* for USB_GADGET_DELAYED_STATUS */
+
+/* Undef helpers from linux/usb/composite.h as gadgetfs redefines them */
+#undef DBG
+#undef ERROR
+#undef INFO
 
 
 /*
@@ -1511,7 +1517,16 @@  gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 			event->u.setup = *ctrl;
 			ep0_readable (dev);
 			spin_unlock (&dev->lock);
-			return 0;
+			/*
+			 * Return USB_GADGET_DELAYED_STATUS as a workaround to
+			 * stop some UDC drivers (e.g. dwc3) from automatically
+			 * proceeding with the status stage for 0-length
+			 * transfers.
+			 * Should be removed once all UDC drivers are fixed to
+			 * always delay the status stage until a response is
+			 * queued to EP0.
+			 */
+			return w_length == 0 ? USB_GADGET_DELAYED_STATUS : 0;
 		}
 	}