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SubjectRe: [PATCH] DMA: TXx9 Soc DMA Controller driver (v2)
Atsushi Nemoto wrote:
> On Sat, 18 Apr 2009 13:05:15 -0700, Dan Williams <dan.j.williams@intel.com> wrote:
>> Not quite "ackable" yet...
>
> Thank you for review!
>
>>> +#ifdef CONFIG_MACH_TX49XX
>>> +#define TXX9_DMA_MAY_HAVE_64BIT_REGS
>>> +#define TXX9_DMA_HAVE_CCR_LE
>>> +#define TXX9_DMA_HAVE_SMPCHN
>>> +#define TXX9_DMA_HAVE_IRQ_PER_CHAN
>>> +#endif
>>> +
>>> +#ifdef TXX9_DMA_HAVE_SMPCHN
>>> +#define TXX9_DMA_USE_SIMPLE_CHAIN
>>> +#endif
>>> +
>> There seems to be a lot of ifdef magic in the code based on these
>> defines. Can we move this magic and some of the pure definitions to
>> drivers/dma/txx9dmac.h? (See the "#ifdefs are ugly" section of
>> Documentation/SubmittingPatches)
>
> OK, I will try to clean them up. But since I don't want to export
> internal implementation details, some of the magics will be left in
> txx9dmac.c, perhaps.

You only need to hide txx9dmac magic if the header was in
include/linux/, but since it will be in drivers/dma/ you can assume it
is private.
}
>> Is there a reason to keep f'irst' off of the tx_list? It seems like
>> you could simplify this logic and get rid of the scary looking
>> list_splice followed by list_add in txx9dmac_desc_put. It also seems
>> odd that the descriptors on tx_list are not reachable from the
>> dc->queue list after a submit... but maybe I am missing a subtle
>> detail?
>
> Well, I'm not sure what do you mean...
>
> The completion callback handler of the first descriptor should be
> called _after_ the completion of the _last_ child of the descriptor.
> Also I use desc_node for both dc->queue, dc->active_list and
> txd.tx_list. So if I putted all children to dc->queue or
> dc->active_list, txx9dmac_descriptor_complete() (or its caller) will
> be more complex.
>
> Or do you mean adding another list_head to maintain txd.tx_list? Or
> something another at all?

The piece I was missing was that it would make
txx9dmac_descriptor_complete() more complex. So, I am fine with the
leaving the current implementation.

Regards,
Dan


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