Hi,

* Shilimkar, Santosh <[email protected]> [081216 14:05]:
> Tony,
> Here is the patch for DMA to ease the chaining usage. OMAP mcbsp drivers 
> makes use of this chaining feature but it's not pushed on mainline yet. It's 
> available on zoom tree. Link for the same driver. 
> http://git.omapzoom.org/?p=omapkernel.git;a=blob;f=arch/arm/mach-omap2/mcbsp.c;h=ce726c5d27eedb678ad3f981e2f5e08134e44e27;hb=2af15d1d7931a7c928d84057ed4494b77769de12

Hmm, the omap2_mcbsp_rx_dma_callback() and omap2_mcbsp_tx_dma_callback()
don't even use the lch parameter passed to them in the example above.

And can't you just use the data->chain_id to get the chain in the
callback function?

Tony



> 
> 
> From: Santosh Shilimkar <[email protected]>
> 
> This patch reverts back the change done on OMAP dma library. It corrects the 
> chaining callback and reduces the complexity for the DMA users in chaining. 
> So with this patch, drivers making use of OMAP DMA chaining feature need not 
> built any intelligence for chain related transfers in their callback using 
> private data. 
> 
> Signed-off-by: Santosh Shilimkar <[email protected]>
> Acked By : Nishant kamat <[email protected]>
> ---
> --- omapkernel.orig/arch/arm/plat-omap/dma.c  2008-12-04 11:11:07.000000000 
> +0530
> +++ omapkernel/arch/arm/plat-omap/dma.c       2008-12-16 16:59:42.066118383 
> +0530
> @@ -1936,7 +1936,11 @@ static int omap2_dma_handle_ch(int ch)
>       }
>  
>       if (likely(dma_chan[ch].callback != NULL))
> -             dma_chan[ch].callback(ch, status, dma_chan[ch].data);
> +             if (dma_chan[ch].chain_id != -1)
> +                     dma_chan[ch].callback(dma_chan[ch].chain_id, status,
> +                                           dma_chan[ch].data);
> +             else
> +                     dma_chan[ch].callback(ch, status, dma_chan[ch].data);
>  
>       dma_write(status, CSR(ch));
--
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