Messages in this thread | | | Date | Wed, 3 Jan 2018 11:41:51 -0800 | From | Stephen Boyd <> | Subject | Re: [RESEND PATCH v2 14/15] ASoC: qcom: apq8096: Add db820c machine driver |
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On 01/03, Srinivas Kandagatla wrote: > Thanks for your review comments, > > On 03/01/18 17:20, Stephen Boyd wrote: > >>+ > >>+ return ret; > >>+} > >>+ > >>+static int msm_snd_apq8096_probe(struct platform_device *pdev) > >>+{ > >>+ int ret; > >>+ struct snd_soc_card *card; > >>+ > >>+ card = devm_kzalloc(&pdev->dev, sizeof(*card), GFP_KERNEL); > >>+ if (!card) > >>+ return -ENOMEM; > >>+ > >>+ card->dev = &pdev->dev; > >>+ > >>+ 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? > > Even though dsp supports 64 bit addresses, but the sid sits at > offset of 32, which brings this restriction of supporting only 32 > bit iova. >
Doesn't the dsp have an iommu in place to make the address translation from 64 to 32 bits transparent? I thought this was what dma-ranges and iommu binding was for, but I'm not well versed on all the details here.
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