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authorMike Frysinger <vapier@gentoo.org>2011-03-30 22:48:54 -0400
committerFelipe Balbi <balbi@ti.com>2011-04-13 11:51:28 +0300
commit132543074af3cf1e94e3608abf162880edbdcbb3 (patch)
tree498abf639ee20de505593f776756d40fdcbe9d1c /drivers/usb/musb/blackfin.c
parent4f9edd2d7e8dd170d10780532cb76eb5890468b4 (diff)
USB: musb: blackfin: work around anomaly 05000450
DMA mode 1 data corruption anomaly on Blackfin systems. This issue is specific to the Blackfin silicon as the bug appears to be related to the connection of the musb ip to the bus/dma fabric. Data corruption when using USB DMA mode 1. (Issue manager 17-01-0105) DMA mode 1 allows large size transfers to generate a single interrupt at the end of the entire transfer. The transfer is split up in packets of length specified in the Maximum Packet Size field for that endpoint. If the transfer size is not an integer multiple of the Maximum Packet Size, a short packet will be present at the end of the transfer. Under certain conditions this packet may be corrupted in the USB FIFO. Workaround: Use DMA mode 1 to transfer (n* Maximum Packet Size) and schedule DMA mode 0 to transfer the short packet. As an example if your transfer size is 33168 bytes and Maximum Packet Size equals 512, schedule [33168 - (33168 mod 512)] in DMA mode 1 and the remainder (33168 mod 512) in DMA mode 0. Signed-off-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers/usb/musb/blackfin.c')
-rw-r--r--drivers/usb/musb/blackfin.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/usb/musb/blackfin.c b/drivers/usb/musb/blackfin.c
index 52312e8af213..8e2a1ff8a35a 100644
--- a/drivers/usb/musb/blackfin.c
+++ b/drivers/usb/musb/blackfin.c
@@ -21,6 +21,7 @@
#include <asm/cacheflush.h>
#include "musb_core.h"
+#include "musbhsdma.h"
#include "blackfin.h"
struct bfin_glue {
@@ -332,6 +333,27 @@ static int bfin_musb_set_mode(struct musb *musb, u8 musb_mode)
return -EIO;
}
+static int bfin_musb_adjust_channel_params(struct dma_channel *channel,
+ u16 packet_sz, u8 *mode,
+ dma_addr_t *dma_addr, u32 *len)
+{
+ struct musb_dma_channel *musb_channel = channel->private_data;
+
+ /*
+ * Anomaly 05000450 might cause data corruption when using DMA
+ * MODE 1 transmits with short packet. So to work around this,
+ * we truncate all MODE 1 transfers down to a multiple of the
+ * max packet size, and then do the last short packet transfer
+ * (if there is any) using MODE 0.
+ */
+ if (ANOMALY_05000450) {
+ if (musb_channel->transmit && *mode == 1)
+ *len = *len - (*len % packet_sz);
+ }
+
+ return 0;
+}
+
static void bfin_musb_reg_init(struct musb *musb)
{
if (ANOMALY_05000346) {
@@ -430,6 +452,8 @@ static const struct musb_platform_ops bfin_ops = {
.vbus_status = bfin_musb_vbus_status,
.set_vbus = bfin_musb_set_vbus,
+
+ .adjust_channel_params = bfin_musb_adjust_channel_params,
};
static u64 bfin_dmamask = DMA_BIT_MASK(32);