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SubjectRe: [PATCH] serial: sh-sci: don't filter on DMA device, use only channel ID
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On Tue, 2011-08-30 at 13:20 +0200, Guennadi Liakhovetski wrote:
> On Tue, 30 Aug 2011, Vinod Koul wrote:
>
> > On Tue, 2011-08-30 at 09:54 +0200, Guennadi Liakhovetski wrote:
> > > On Mon, 29 Aug 2011, Vinod Koul wrote:
> > > > > >> You should not assign chan->private.
> > > > > >> Please move this to dma_slave_control API
> > > > > >
> > > > > > I haven't seen any reply to this comment and this patch seems to still be
> > > > > > outstanding, is there an updated version of this patch that I've missed?
> > > > I don't recall seeing any updated version fixing this
> > >
> > > As a matter of fact, when you say "use dma_slave_control API," you
> > > actually mean the dma_slave_config, right? Then, how is one supposed to
> > > use it in this case? Shall we be issuing a DMA_SLAVE_CONFIG call inside of
> > > the filter and check the return code? The problem is, that not all DMA
> > > controllers on sh-mobile SoCs can service the same slave devices. So, if
> > > we don't check in the filter we might well get an unsuitable DMA channel.
> > Here you are assigning to chan->private your specific values, which
> > should be moved to the dma_slave_config.
> > But here you are removing the checks, and accepting the first channel
> > you got, so how do you find channel is suitable or not.
>
> That's done in the driver's .device_alloc_chan_resources() method. It
> checkx the .private pointer, tries to find a suitable channel, if it fails
> - it returns -EINVAL. See
> drivers/dma/shdma.c::sh_dmae_alloc_chan_resources():
>
> if (param) {
> const struct sh_dmae_slave_config *cfg;
>
> cfg = sh_dmae_find_slave(sh_chan, param);
> if (!cfg) {
> ret = -EINVAL;
> goto efindslave;
> }
Now am doubly confused. Are you saying that you are using
alloc_chan_resources for doing filtering??

--
~Vinod



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