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

Hi Lothar,

On Mon, Feb 07, 2011 at 03:13:50PM +0100, Lothar Wa?mann wrote:

Hi,

Shawn Guo writes:
[...]

quoted

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 @@

[...]

quoted

+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