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 58bc85dd7917edc02fd15fb4e67db9fdceab0fd2..29285f209dcf818d12b4fdc612c910cbc0a31c68 100644 (file)
--- a/drivers/firewire/fw-ohci.c
+++ b/drivers/firewire/fw-ohci.c
@@ -170,6 +170,8 @@ static inline struct fw_ohci *fw_ohci(struct fw_card *card)
 #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 @@ static void ar_context_tasklet(unsigned long data)
        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 @@ static void ar_context_tasklet(unsigned long data)
        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);
 }