[PATCH V4 06/14] ARM: SAMSUNG: Add common DMA operations

[Boojin Kim]

Jassi Brar wrote:
> Sent: Wednesday, July 27, 2011 10:34 AM
> 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 Tue, Jul 26, 2011 at 3:05 PM, Boojin Kim <boojin.kim at samsung.com>
> wrote:
> > 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
> <boojin.kim at samsung.com>
> >> wrote:
> >>
> >> > +
> >> > +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.
> Not for long.
> See  https://lkml.org/lkml/2011/7/26/245
>
>
> >> > +
> >> > +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?
>
> static int s3c_dma_control(unsigned ch, enum s3c2410_chan_op/*or
> similar*/ op)
>  {
>         return s3c2410_dma_ctrl(ch, op);
>  }
>
> static struct samsung_dma_ops s3c_dma_ops = {
>         .request        = s3c_dma_request,
>         .release        = s3c_dma_release,
>         .prepare        = s3c_dma_prepare,
>         .control        = s3c_dma_control,
'Struct samsung_dma_ops' is used for both 'S3C-DMA-OPS' for 's3c dma' and 
'DMA-OPS' for 'dmaengine'.
If I modify "Struct samsung_dma_ops" as your guide, It gives un-expectable 
effect to DMA-OPS.
Actually, We don't want the client with 'DMA-OPS' uses 'enum s3c2410_chan_op' 
operation anymore.