Thread (66 messages) 66 messages, 6 authors, 2018-02-07

Re: [RESEND PATCH v2 14/15] ASoC: qcom: apq8096: Add db820c machine driver

From: Stephen Boyd <hidden>
Date: 2018-01-03 19:41:55
Also in: alsa-devel, linux-arm-kernel, linux-arm-msm, lkml

On 01/03, Srinivas Kandagatla wrote:
Thanks for your review comments,

On 03/01/18 17:20, Stephen Boyd wrote:
quoted
quoted
+
+	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.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
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