Re: [PATCH] ALSA driver for Yamaa AICA on Sega Dreamcast

[Paul Mundt <lethal@linux-sh.org>]

On Mon, Apr 17, 2006 at 12:52:26PM +0300, Paul Mundt wrote:
> Then the G2 DMA ->get_residue() op needs to be fixed, as it's broken.
> Don't work against the subsystem, it knows what it's doing.
> 
> You might be better off getting rid of it entirely and seeing about
> getting the TEI working, you can check for completion and wake up
> accordingly in this case, which is what you ideally want anyways. The
> busy-loop in the generic dma_wait_for_completion() is a stupid hack for
> people that haven't fixed up their TEI handling yet, it's not intended
> for widespread use..
> 
What about something like this?

diff --git a/arch/sh/drivers/dma/dma-g2.c b/arch/sh/drivers/dma/dma-g2.c
index 5afab6f..277581e 100644
--- a/arch/sh/drivers/dma/dma-g2.c
+++ b/arch/sh/drivers/dma/dma-g2.c
@@ -49,7 +49,14 @@ static volatile struct g2_dma_info *g2_d
 
 static irqreturn_t g2_dma_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 {
-	/* FIXME: Do some meaningful completion work here.. */
+	struct dma_channel *chan = dev_id;
+	unsigned int chan_nr = chan->chan;
+	unsigned int bytes;
+
+	bytes = g2_dma->channel[chan_nr].size - g2_dma->status[chan_nr].size;
+	if (likely(bytes == 0))
+		wake_up(&chan->wait_queue);
+
 	return IRQ_HANDLED;
 }
 
@@ -133,10 +140,17 @@ static int g2_xfer_dma(struct dma_channe
 		 g2_dma->channel[chan_nr].xfer_enable);
 
 	return 0;
+}
+
+static int g2_get_dma_residue(struct dma_channel *chan)
+{
+	unsigned int chan_nr = chan->chan;
+	return g2_dma->channel[chan_nr].size - g2_dma->status[chan_nr].size;
 }
 
 static struct dma_ops g2_dma_ops = {
 	.xfer		= g2_xfer_dma,
+	.get_residue	= g2_get_dma_residue,
 };
 
 static struct dma_info g2_dma_info = {


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