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Commit f933a0c0 authored by Anand Gadiyar's avatar Anand Gadiyar Committed by Greg Kroah-Hartman
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usb: musb: workaround MUSB DMA_INTR sometimes reads zero 



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: default avatarAnand Gadiyar <gadiyar@ti.com>
Cc: Ajay Kumar Gupta <ajay.gupta@ti.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: default avatarFelipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 452f0394

drivers/usb/musb/musbhsdma.c

+22 −3
Original line number Diff line number Diff line
@@ -250,20 +250,39 @@ static irqreturn_t dma_controller_irq(int irq, void *private_data) 
	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 *)