USB: musb: add notes for Blackfin anomalies

Add some helpful notes about how the driver works around different
anomalies that exist in the on-chip host controller.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/usb/musb/blackfin.h b/drivers/usb/musb/blackfin.h
index a240c1e53d16..b49a362fb9fa 100644
--- a/drivers/usb/musb/blackfin.h
+++ b/drivers/usb/musb/blackfin.h
@@ -14,6 +14,33 @@
  * Blackfin specific definitions
  */
 
+/* Anomalies notes:
+ *
+ *  05000450 - USB DMA Mode 1 Short Packet Data Corruption:
+ *             MUSB driver is designed to transfer buffer of N * maxpacket size
+ *             in DMA mode 1 and leave the rest of the data to the next
+ *             transfer in DMA mode 0, so we never transmit a short packet in
+ *             DMA mode 1.
+ *
+ *  05000463 - This anomaly doesn't affect this driver since it
+ *             never uses L1 or L2 memory as data destination.
+ *
+ *  05000464 - This anomaly doesn't affect this driver since it
+ *             never uses L1 or L2 memory as data source.
+ *
+ *  05000465 - The anomaly can be seen when SCLK is over 100 MHz, and there is
+ *             no way to workaround for bulk endpoints.  Since the wMaxPackSize
+ *             of bulk is less than or equal to 512, while the fifo size of
+ *             endpoint 5, 6, 7 is 1024, the double buffer mode is enabled
+ *             automatically when these endpoints are used for bulk OUT.
+ *
+ *  05000466 - This anomaly doesn't affect this driver since it never mixes
+ *             concurrent DMA and core accesses to the TX endpoint FIFOs.
+ *
+ *  05000467 - The workaround for this anomaly will introduce another
+ *             anomaly - 05000465.
+ */
+
 #undef DUMP_FIFO_DATA
 #ifdef DUMP_FIFO_DATA
 static void dump_fifo_data(u8 *buf, u16 len)