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SubjectRe: [RESEND PATCH v2 14/15] ASoC: qcom: apq8096: Add db820c machine driver
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On 04/01/18 12:02, Mark Brown wrote:
> On Wed, Jan 03, 2018 at 09:20:45AM -0800, Stephen Boyd wrote:
>> On 12/14/2017 09:34 AM, srinivas.kandagatla@linaro.org wrote:
>
>>> uThis patch adds support to DB820c machine driver.
>
>>> + ret = dma_coerce_mask_and_coherent(card->dev, DMA_BIT_MASK(32));
>
>> Why do we need to do this? Can you add some sort of comment in the code
>> about why?
>
> And why are we applying DMA restrictions in a machine driver?

Initially I had this in pcm driver, but looking at example usage of
snd_dma_alloc_pages, most of them use card->dev and some of them use pcm
device for allocating dma memory.

Also, as I moved most dsp static services and dais out of DT, except
codec and sound card, sound card device was the only choice I had for
binding with iommu and enforcing iova range restrictions.

This call will be replaced by dma-ranges property in DT either way.


--srini
>

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