Jassi Brar Wrote:

Sent: Monday, July 25, 2011 8:52 PM
To: Boojin Kim
Cc: linux-arm-kernel at lists.infradead.org; linux-samsung-
soc at vger.kernel.org; Vinod Koul; Dan Williams; Kukjin Kim; Grant
Likely; Mark Brown
Subject: Re: [PATCH V4 06/14] ARM: SAMSUNG: Add common DMA operations

On Mon, Jul 25, 2011 at 6:58 AM, Boojin Kim [off-list ref]
wrote:

quoted

+
+static bool pl330_filter(struct dma_chan *chan, void *param)
+{
+       struct dma_pl330_peri *peri = (struct dma_pl330_peri *)chan-
private;
+       unsigned dma_ch = (unsigned)param;
+
+       if (peri->peri_id != dma_ch)
+               return false;
+
+       return true;
+}

This is what I meant... if we keep chan_id for paltform assigned IDs,
these filter functions could simply become

static bool pl330_filter(struct dma_chan *chan, void *param)
{
        return chan->chan_id == param
}

And ideally in the long run, we could just drop the filter callback
and add expected channel ID to the request_channel call.

The chan_id is set by dmaengine. So, We don't use it to hold the user specific 
Id.

quoted

+
+static inline int s3c_dma_trigger(unsigned ch)
+{
+       return s3c2410_dma_ctrl(ch, S3C2410_DMAOP_START);
+}
+
+static inline int s3c_dma_started(unsigned ch)
+{
+       return s3c2410_dma_ctrl(ch, S3C2410_DMAOP_STARTED);
+}
+
+static inline int s3c_dma_flush(unsigned ch)
+{
+       return s3c2410_dma_ctrl(ch, S3C2410_DMAOP_FLUSH);
+}
+
+static inline int s3c_dma_stop(unsigned ch)
+{
+       return s3c2410_dma_ctrl(ch, S3C2410_DMAOP_STOP);
+}
+
+static struct samsung_dma_ops s3c_dma_ops = {
+       .request        = s3c_dma_request,
+       .release        = s3c_dma_release,
+       .prepare        = s3c_dma_prepare,
+       .trigger        = s3c_dma_trigger,
+       .started        = s3c_dma_started,
+       .flush          = s3c_dma_flush,
+       .stop           = s3c_dma_stop,

These last 4 should be gnereallized into one callback with OP argument.

I don't have any idea about it. Can you explain it in more detail?