Hi Shimoda-san

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

Hello Guennadi-san,

2012/01/26 23:56, Guennadi Liakhovetski wrote:

...

This patch adds a library of functions, helping to implement dmaengine drivers for hardware, unable to handle scatter-gather lists natively. The first version of this driver only supports memcpy and slave DMA operation.

Signed-off-by: Guennadi Liakhovetski g.liakhovetski@gmx.de

v2:

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.

Thanks Guennadi

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/