MUSB DMA_INTR register may sometimes read zero when infact there
was a pending interrupt. Workaround this by reading the DMA_COUNT
values for all enabled channels when this condition occurs.
Flag these channels as the ones needing to be serviced.
Signed-off-by: Anand Gadiyar <gadiyar@xxxxxx>
Cc: Ajay Kumar Gupta <ajay.gupta@xxxxxx>
Cc: Felipe Balbi <felipe.balbi@xxxxxxxxx>
Cc: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Cc: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
---
This issue exists on versions of the controller newer than 1.8.
The first version of this patch checked for this version
before acting. However to keep the code clean, I felt that
it is acceptable to do this unconditionally on all versions.
Also, the absence of the debug print meant that we would
never catch a spurious DMA interrupt on the older versions,
so adding the prints helps there.
drivers/usb/musb/musbhsdma.c | 24 ++++++++++++++++++++++--
1 files changed, 22 insertions(+), 2 deletions(-)
Index: linux-omap-2.6/drivers/usb/musb/musbhsdma.c
===================================================================
--- linux-omap-2.6.orig/drivers/usb/musb/musbhsdma.c
+++ linux-omap-2.6/drivers/usb/musb/musbhsdma.c
@@ -256,14 +256,34 @@ static irqreturn_t dma_controller_irq(in
spin_lock_irqsave(&musb->lock, flags);
int_hsdma = musb_readb(mbase, MUSB_HSDMA_INTR);
- if (!int_hsdma)
- goto done;
#ifdef CONFIG_BLACKFIN
/* Clear DMA interrupt flags */
musb_writeb(mbase, MUSB_HSDMA_INTR, int_hsdma);
#endif
+ if (!int_hsdma) {
+ DBG(2, "spurious DMA irq\n");
+
+ for (bchannel = 0; bchannel < MUSB_HSDMA_CHANNELS; bchannel++) {
+ musb_channel = (struct musb_dma_channel *)
+ &(controller->channel[bchannel]);
+ channel = &musb_channel->channel;
+ if (channel->status == MUSB_DMA_STATUS_BUSY) {
+ csr = musb_readw(mbase,
+ MUSB_HSDMA_CHANNEL_OFFSET(bchannel,
+ MUSB_HSDMA_COUNT));
+ if (csr == 0)
+ int_hsdma |= (1 << bchannel);
+ }
+ }
+
+ DBG(2, "int_hsdma = 0x%x\n", int_hsdma);
+
+ if (!int_hsdma)
+ goto done;
+ }
+
for (bchannel = 0; bchannel < MUSB_HSDMA_CHANNELS; bchannel++) {
if (int_hsdma & (1 << bchannel)) {
musb_channel = (struct musb_dma_channel *)
--
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