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.
Additionally, the absence of a debug print meant we would never
catch a spurious DMA interrupt in MUSB. So this patch adds a
debug print in the IRQ handler.
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>
Cc: Vikram Pandita <vikram.pandita@xxxxxx>
---
This is a fix for buggy hardware (OMAP3630, OMAP4430).
Please queue this up for the -rc series if possible.
v2: Fix a bug in v1 pointed out by Vikram.
DMA_COUNT is a 32 bit register, while csr is a 16 bit variable
Also, use the wrapper API to read the register.
drivers/usb/musb/musbhsdma.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
Index: linux-2.6/drivers/usb/musb/musbhsdma.c
===================================================================
--- linux-2.6.orig/drivers/usb/musb/musbhsdma.c 2009-12-18 19:53:39.000000000 +0530
+++ linux-2.6/drivers/usb/musb/musbhsdma.c 2009-12-18 19:55:17.000000000 +0530
@@ -250,20 +250,39 @@ static irqreturn_t dma_controller_irq(in
u8 bchannel;
u8 int_hsdma;
- u32 addr;
+ u32 addr, count;
u16 csr;
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) {
+ count = musb_read_hsdma_count(mbase, bchannel);
+
+ if (count == 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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