usb: ci_udc: don't assume QTDs are adjacent when transmitting ZLPs

Fix ci_ep_submit_next_request()'s ZLP transmission code to explicitly call ci_get_qtd() to find the address of the other QTD to use. This will allow us to correctly align each QTD individually in the future, which may involve leaving a gap between the QTDs. Signed-off-by: Stephen Warren <swarren@nvidia.com>

usb: ci_udc: don't assume QTDs are adjacent when transmitting ZLPs
Fix ci_ep_submit_next_request()'s ZLP transmission code to explicitly call ci_get_qtd() to find the address of the other QTD to use. This will allow us to correctly align each QTD individually in the future, which may involve leaving a gap between the QTDs. Signed-off-by: Stephen Warren <swarren@nvidia.com>
Stephen Warren · Marek Vasut
1 parent d7beeb9358
Showing 1 changed file with 4 additions and 3 deletions Side-by-side Diff
drivers/usb/gadget/ci_udc.c
@@ -404,10 +404,11 @@
 		 * only 1 is used at a time since either an IN or an OUT but
 		 * not both is queued. For an IN transaction, item currently
 		 * points at the second of these items, so we know that we
-		 * can use (item - 1) to transmit the extra zero-length packet
+		 * can use the other to transmit the extra zero-length packet.
 		 */
-		item->next = (unsigned)(item - 1);
-		item--;
+		struct ept_queue_item *other_item = ci_get_qtd(num, 0);
+		item->next = (unsigned)other_item;
+		item = other_item;
 		item->info = INFO_ACTIVE;
 	}
...	...	@@ -404,10 +404,11 @@
404	404	* only 1 is used at a time since either an IN or an OUT but
405	405	* not both is queued. For an IN transaction, item currently
406	406	* points at the second of these items, so we know that we
407		- * can use (item - 1) to transmit the extra zero-length packet
	407	+ * can use the other to transmit the extra zero-length packet.
408	408	*/
409		- item->next = (unsigned)(item - 1);
410		- item--;
	409	+ struct ept_queue_item *other_item = ci_get_qtd(num, 0);
	410	+ item->next = (unsigned)other_item;
	411	+ item = other_item;
411	412	item->info = INFO_ACTIVE;
412	413	}
413	414