Re: [PATCH] serial: sh-sci: don't filter on DMA device, use only channel ID

[Vinod Koul <vinod.koul@linux.intel.com>]

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