linux-kernel - Re: [PATCH 4/7] dmaengine: sprd: Add device validation to support multiple controllers

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Date:   Mon, 29 Apr 2019 20:20:26 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Dan Williams <dan.j.williams@...el.com>, eric.long@...soc.com,
        Orson Zhai <orsonzhai@...il.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Mark Brown <broonie@...nel.org>, dmaengine@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/7] dmaengine: sprd: Add device validation to support
 multiple controllers

On Mon, 29 Apr 2019 at 19:57, Vinod Koul <vkoul@...nel.org> wrote:
>
> On 15-04-19, 20:14, Baolin Wang wrote:
> > From: Eric Long <eric.long@...soc.com>
> >
> > Since we can support multiple DMA engine controllers, we should add
> > device validation in filter function to check if the correct controller
> > to be requested.
> >
> > Signed-off-by: Eric Long <eric.long@...soc.com>
> > Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> > ---
> >  drivers/dma/sprd-dma.c |    5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/dma/sprd-dma.c b/drivers/dma/sprd-dma.c
> > index 0f92e60..9f99d4b 100644
> > --- a/drivers/dma/sprd-dma.c
> > +++ b/drivers/dma/sprd-dma.c
> > @@ -1020,8 +1020,13 @@ static void sprd_dma_free_desc(struct virt_dma_desc *vd)
> >  static bool sprd_dma_filter_fn(struct dma_chan *chan, void *param)
> >  {
> >       struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
> > +     struct of_phandle_args *dma_spec =
> > +             container_of(param, struct of_phandle_args, args[0]);
> >       u32 slave_id = *(u32 *)param;
> >
> > +     if (chan->device->dev->of_node != dma_spec->np)
>
> Are you not using of_dma_find_controller() that does this, so this would
> be useless!

Yes, we can use of_dma_find_controller(), but that will be a little
complicated than current solution. Since we need introduce one
structure to save the node to validate in the filter function like
below, which seems make things complicated. But if you still like to
use of_dma_find_controller(), I can change to use it in next version.
Thank.

struct sprd_dma_filter_param {
     struct device_node *np;
};

static struct dma_chan* sprd_dma_xlate(struct of_phandle_args
*dma_spec, struct of_dma *of_dma)
{
    param.np = dma_spec->node;

    return dma_request_channel(xxx);
}

of_dma_controller_register(np, sprd_dma_xlate, sdev);

-- 
Baolin Wang
Best Regards