firewire: Make sure we wait for DMA to stop before we reprogram it.
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/fw-ohci.c b/drivers/firewire/fw-ohci.c
index 58bc85d..29285f2 100644
--- a/drivers/firewire/fw-ohci.c
+++ b/drivers/firewire/fw-ohci.c
@@ -170,6 +170,8 @@
#define OHCI1394_PCI_HCI_Control 0x40
#define SELF_ID_BUF_SIZE 0x800
+#define MAX_STOP_CONTEXT_LOOPS 1000
+
static char ohci_driver_name[] = KBUILD_MODNAME;
static inline void reg_write(const struct fw_ohci *ohci, int offset, u32 data)
@@ -224,6 +226,13 @@
struct fw_ohci *ohci = ctx->ohci;
struct fw_packet p;
u32 status, length, tcode;
+ int i;
+
+ /* FIXME: We stop and restart the ar context here, what if we
+ * stop while a receive is in progress? Maybe we could just
+ * loop the context back to itself and use it in buffer fill
+ * mode as intended... */
+ reg_write(ctx->ohci, ctx->control_clear, CONTEXT_RUN);
/* FIXME: What to do about evt_* errors? */
length = le16_to_cpu(ctx->descriptor.req_count) -
@@ -287,12 +296,14 @@
dma_sync_single_for_device(ohci->card.device, ctx->descriptor_bus,
sizeof ctx->descriptor_bus, DMA_TO_DEVICE);
- /* FIXME: We stop and restart the ar context here, what if we
- * stop while a receive is in progress? Maybe we could just
- * loop the context back to itself and use it in buffer fill
- * mode as intended... */
+ /* Make sure the active bit is 0 before we reprogram the DMA. */
+ for (i = 0; i < MAX_STOP_CONTEXT_LOOPS; i++)
+ if (!(reg_read(ctx->ohci,
+ ctx->control_clear) & CONTEXT_ACTIVE))
+ break;
+ if (i == MAX_STOP_CONTEXT_LOOPS)
+ fw_error("Failed to stop ar context\n");
- reg_write(ctx->ohci, ctx->control_clear, CONTEXT_RUN);
ar_context_run(ctx);
}