Hi Guennadi-san,

2012/01/27 17:48, Guennadi Liakhovetski wrote:

Hi Shimoda-san

On Fri, 27 Jan 2012, Shimoda, Yoshihiro wrote:

[ snip ]

quoted

quoted

1. switch from using a tasklet to threaded IRQ, which allowed to

I tested this driver on 2 environment, but it could not work correctly.
 - renesas_usbhs driver with shdma driver on the mackerel board
 - renesas_usbhs driver with experimental SUDMAC driver

In this case, should we modify the renesas_usbhs driver?

Yes, you do. Please, see the respective version of the shdma patch. It 
doesn't request channel IRQs any more directly, instead, it uses a 
dma-simple wrapper function. Also operations change a bit.

Thank you for your comment.

I investigaed the issue. I found out the renesas_usbhs driver may
call tx_submit() in the callback() of the dma-simple finally.
In this case, the value of power_up in the simple_tx_submit is 0,
the start_xfer() is not called. And then, even if the ld_queue is
not empty, the DMA doesn't start.


So, if I add codes like the following in the dma-simple.c,
the renesas_usbhs driver can work correctly without the driver changes.
If you think the code is good, would you merge it to your code?
======= chan_irqt() =======
	simple_chan_ld_cleanup(schan, false);

+	spin_lock_irq(&schan->chan_lock);
+	/* Next desc */
+	simple_chan_xfer_ld_queue(schan);
+	spin_unlock_irq(&schan->chan_lock);

	return IRQ_HANDLED;
==============

Best regards,
Yoshihiro Shimoda

Thanks
Guennadi

quoted

For reference, if I changed the threaded IRQ to tasklet,
the 2 environment worked correctly:
==============

diff --git a/drivers/dma/dma-simple.c b/drivers/dma/dma-simple.c
index 49d8f7d..65a5170 100644
--- a/drivers/dma/dma-simple.c
+++ b/drivers/dma/dma-simple.c

@@ -715,16 +715,18 @@ static irqreturn_t chan_irq(int irq, void *dev)

 	spin_lock(&schan->chan_lock);

-	ret = ops->chan_irq(schan, irq) ? IRQ_WAKE_THREAD : IRQ_NONE;
+	ret = ops->chan_irq(schan, irq) ? IRQ_HANDLED : IRQ_NONE;
+	if (ret == IRQ_HANDLED)
+		tasklet_schedule(&schan->tasklet);

 	spin_unlock(&schan->chan_lock);

 	return ret;
 }

-static irqreturn_t chan_irqt(int irq, void *dev)
+static void chan_irqt(unsigned long dev)
 {
-	struct dma_simple_chan *schan = dev;
+	struct dma_simple_chan *schan = (struct dma_simple_chan *)dev;
 	const struct dma_simple_ops *ops =
 		to_simple_dev(schan->dma_chan.device)->ops;
 	struct dma_simple_desc *sdesc;

@@ -744,15 +746,13 @@ static irqreturn_t chan_irqt(int irq, void *dev)
 	spin_unlock_irq(&schan->chan_lock);

 	simple_chan_ld_cleanup(schan, false);
-
-	return IRQ_HANDLED;
 }

 int dma_simple_request_irq(struct dma_simple_chan *schan, int irq,
 			   unsigned long flags, const char *name)
 {
-	int ret = request_threaded_irq(irq, chan_irq, chan_irqt,
-				       flags, name, schan);
+	int ret = request_irq(irq, chan_irq, flags, name, schan);
+	tasklet_init(&schan->tasklet, chan_irqt, (unsigned long)schan);

 	schan->irq = ret < 0 ? ret : irq;

diff --git a/include/linux/dma-simple.h b/include/linux/dma-simple.h
index 5336674..beb1489 100644
--- a/include/linux/dma-simple.h
+++ b/include/linux/dma-simple.h

@@ -68,6 +68,7 @@ struct dma_simple_chan {
 	int id;				/* Raw id of this channel */
 	int irq;			/* Channel IRQ */
 	enum dma_simple_pm_state pm_state;
+	struct tasklet_struct tasklet;
 };

 /**

==============

Best regards,
Yoshihiro Shimoda

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

-- 
Yoshihiro Shimoda [off-list ref]
EC No.