[PATCH 1/5] dmaengine: mxs-dma: add dma support for i.MX23/28

[Shawn Guo]

Hi Lothar,

On Mon, Feb 07, 2011 at 03:13:50PM +0100, Lothar Waßmann wrote:
> Hi,
> 
> Shawn Guo writes:
> [...]
> > diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
> > new file mode 100644
> > index 0000000..8d1e811
> > --- /dev/null
> > +++ b/drivers/dma/mxs-dma.c
> > @@ -0,0 +1,702 @@
> [...]
> > +static irqreturn_t mxs_dma_int_handler(int irq, void *dev_id)
> > +{
> > +	struct mxs_dma_engine *mxs_dma = dev_id;
> > +	u32 stat1, stat2;
> > +
> > +	/* completion status */
> > +	stat1 = __raw_readl(mxs_dma->base + HW_APBHX_CTRL1);
> > +	stat1 &= 0xffff;
> > +	__mxs_clrl(stat1, mxs_dma->base + HW_APBHX_CTRL1);
> > +
> > +	/* error status */
> > +	stat2 = __raw_readl(mxs_dma->base + HW_APBHX_CTRL2);
> > +	__mxs_clrl(stat2, mxs_dma->base + HW_APBHX_CTRL2);
> > +
> > +	/*
> > +	 * When both completion and error of termination bits set at the
> > +	 * same time, we do not take it as an error.  IOW, it only becomes
> > +	 * an error we need to handler here in case of ether it's an bus
> > +	 * error or a termination error with no completion.
> > +	 */
> > +	stat2 = ((stat2 >> 16) & stat2) |	   /* bus error */
> > +		(~(stat2 >> 16) & stat2 & ~stat1); /* termination with no completion */
> > +
> > +	/* combine error and completion status for checking */
> > +	stat1 = (stat2 << 16) | stat1;
> > +	while (stat1) {
> > +		int channel = fls(stat1) - 1;
> > +		struct mxs_dma_chan *mxs_chan =
> > +				&mxs_dma->mxs_chans[channel % 16];
> > +
> > +		if (channel >= 16) {
> > +			dev_dbg(mxs_dma->dev, "%s: error in channel %d\n",
> > +						__func__, channel - 16);
> > +			mxs_dma_reset_chan(mxs_chan);
> > +			mxs_chan->status = DMA_ERROR;
> > +		} else {
> > +			if (mxs_chan->flags & MXS_DMA_SG_LOOP)
> > +				mxs_chan->status = DMA_IN_PROGRESS;
> > +			else
> > +				mxs_chan->status = DMA_SUCCESS;
> > +		}
> > +
> > +		stat1 &= ~(1 << channel);
> > +
> > +		if (mxs_chan->desc.callback)
> > +			mxs_chan->desc.callback(mxs_chan->desc.callback_param);
> > +
> > +		if (mxs_chan->status == DMA_SUCCESS)
> > +			mxs_chan->last_completed = mxs_chan->desc.cookie;
> > +	}
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int mxs_dma_alloc_chan_resources(struct dma_chan *chan)
> > +{
> > +	struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(chan);
> > +	struct mxs_dma_data *data = chan->private;
> > +	struct mxs_dma_engine *mxs_dma = mxs_chan->mxs_dma;
> > +	static unsigned long flags;
> > +	int ret;
> > +
> > +	if (!data)
> > +		return -EINVAL;
> > +
> > +	mxs_chan->chan_irq = data->chan_irq;
> > +
> > +	mxs_chan->ccw = dma_alloc_coherent(NULL, PAGE_SIZE,
> > +				&mxs_chan->ccw_phys, GFP_KERNEL);
> > +	if (!mxs_chan->ccw) {
> > +		ret = -ENOMEM;
> > +		goto err_alloc;
> > +	}
> > +
> > +	memset(mxs_chan->ccw, 0, PAGE_SIZE);
> > +
> > +	ret = request_irq(mxs_chan->chan_irq, mxs_dma_int_handler,
> > +				flags, "mxs-dma", mxs_dma);
> > +	if (ret)
> > +		goto err_irq;
> > +
> > +	flags = IRQF_SHARED;
> > +
> Apart from the fact, that this is initilized after use, the use of
> IRQF_SHARED is wrong here. Shared interrupt handlers are for
> multiple handlers sharing a single interrupt source, not for multiple
> interrupt sources sharing the same handler!
> A shared handler must return IRQ_NONE, if it detects that the
> interrupt was from a source it does not handle.
> 
My bad.  Thanks for pointing this out.

Regards,
Shawn