[v3,08/28] ASoC: qcom: Add USB backend ASoC driver for Q6

  Create a USB BE component that will register a new USB port to the ASoC USB
framework.  This will handle determination on if the requested audio
profile is supported by the USB device currently selected.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
 include/sound/q6usboffload.h  |  20 ++++
 sound/soc/qcom/Kconfig        |   4 +
 sound/soc/qcom/qdsp6/Makefile |   1 +
 sound/soc/qcom/qdsp6/q6usb.c  | 208 ++++++++++++++++++++++++++++++++++
 4 files changed, 233 insertions(+)
 create mode 100644 include/sound/q6usboffload.h
 create mode 100644 sound/soc/qcom/qdsp6/q6usb.c
  

On 08/03/2023 23:57, Wesley Cheng wrote:
> Create a USB BE component that will register a new USB port to the ASoC USB
> framework.  This will handle determination on if the requested audio
> profile is supported by the USB device currently selected.
> 
> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>

Thanks Wesley for the patch, I have few minor comments.

> ---
>   include/sound/q6usboffload.h  |  20 ++++
>   sound/soc/qcom/Kconfig        |   4 +
>   sound/soc/qcom/qdsp6/Makefile |   1 +
>   sound/soc/qcom/qdsp6/q6usb.c  | 208 ++++++++++++++++++++++++++++++++++
>   4 files changed, 233 insertions(+)
>   create mode 100644 include/sound/q6usboffload.h
>   create mode 100644 sound/soc/qcom/qdsp6/q6usb.c
> 
> diff --git a/include/sound/q6usboffload.h b/include/sound/q6usboffload.h
> new file mode 100644
> index 000000000000..4fb1912d9f55
> --- /dev/null
> +++ b/include/sound/q6usboffload.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0
> + *
> + * linux/sound/q6usboffload.h -- QDSP6 USB offload
> + *
> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +/**
> + * struct q6usb_offload
> + * @dev - dev handle to usb be
> + * @sid - streamID for iommu
> + * @intr_num - usb interrupter number
> + * @domain - allocated iommu domain
> + **/
> +struct q6usb_offload {
> +	struct device *dev;
> +	long long sid;
> +	u32 intr_num;
> +	struct iommu_domain *domain;
Why do we need to store this domain, You can remove this along with the 
one line that gets domain in probe function.

> +};
> diff --git a/sound/soc/qcom/Kconfig b/sound/soc/qcom/Kconfig
> index e7b00d1d9e99..bb285af6bb04 100644
> --- a/sound/soc/qcom/Kconfig
> +++ b/sound/soc/qcom/Kconfig
> @@ -114,6 +114,9 @@ config SND_SOC_QDSP6_APM
>   config SND_SOC_QDSP6_PRM_LPASS_CLOCKS
>   	tristate
>   
> +config SND_SOC_QDSP6_USB
> +	tristate
> +
>   config SND_SOC_QDSP6_PRM
>   	tristate
>   	select SND_SOC_QDSP6_PRM_LPASS_CLOCKS
> @@ -134,6 +137,7 @@ config SND_SOC_QDSP6
>   	select SND_SOC_TOPOLOGY
>   	select SND_SOC_QDSP6_APM
>   	select SND_SOC_QDSP6_PRM
> +	select SND_SOC_QDSP6_USB
>   	help
>   	 To add support for MSM QDSP6 Soc Audio.
>   	 This will enable sound soc platform specific
> diff --git a/sound/soc/qcom/qdsp6/Makefile b/sound/soc/qcom/qdsp6/Makefile
> index 3963bf234664..c9457ee898d0 100644
> --- a/sound/soc/qcom/qdsp6/Makefile
> +++ b/sound/soc/qcom/qdsp6/Makefile
> @@ -17,3 +17,4 @@ obj-$(CONFIG_SND_SOC_QDSP6_APM_DAI) += q6apm-dai.o
>   obj-$(CONFIG_SND_SOC_QDSP6_APM_LPASS_DAI) += q6apm-lpass-dais.o
>   obj-$(CONFIG_SND_SOC_QDSP6_PRM) += q6prm.o
>   obj-$(CONFIG_SND_SOC_QDSP6_PRM_LPASS_CLOCKS) += q6prm-clocks.o
> +obj-$(CONFIG_SND_SOC_QDSP6_USB) += q6usb.o
> diff --git a/sound/soc/qcom/qdsp6/q6usb.c b/sound/soc/qcom/qdsp6/q6usb.c
> new file mode 100644
> index 000000000000..3d480550b3f3
> --- /dev/null
> +++ b/sound/soc/qcom/qdsp6/q6usb.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/iommu.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dma-map-ops.h>

you would not need these 3 includes aswell.

> +
> +#include <sound/pcm.h>
> +#include <sound/soc.h>
> +#include <sound/soc-usb.h>
> +#include <sound/pcm_params.h>
> +#include <sound/asound.h>
> +#include <sound/q6usboffload.h>
> +
> +#include "q6dsp-lpass-ports.h"
> +#include "q6afe.h"
> +
> +#define SID_MASK	0xF
> +
> +struct q6usb_port_data {
> +	struct q6afe_usb_cfg usb_cfg;
> +	struct snd_soc_usb *usb;
> +	struct q6usb_offload priv;
> +	int active_idx;
> +};
> +
> +static const struct snd_soc_dapm_widget q6usb_dai_widgets[] = {
> +	SND_SOC_DAPM_HP("USB_RX_BE", NULL),
> +};
> +
> +static const struct snd_soc_dapm_route q6usb_dapm_routes[] = {
> +	{"USB Playback", NULL, "USB_RX_BE"},
> +};
> +
> +static int q6usb_hw_params(struct snd_pcm_substream *substream,
> +			   struct snd_pcm_hw_params *params,
> +			   struct snd_soc_dai *dai)
> +{
> +	return 0;
> +}
> +static const struct snd_soc_dai_ops q6usb_ops = {
> +	.hw_params = q6usb_hw_params,
> +};
> +
> +static struct snd_soc_dai_driver q6usb_be_dais[] = {
> +	{
> +		.playback = {
> +			.stream_name = "USB BE RX",
> +			.rates = SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_11025 |
> +				SNDRV_PCM_RATE_16000 | SNDRV_PCM_RATE_22050 |
> +				SNDRV_PCM_RATE_32000 | SNDRV_PCM_RATE_44100 |
> +				SNDRV_PCM_RATE_48000 | SNDRV_PCM_RATE_96000 |
> +				SNDRV_PCM_RATE_192000,
> +			.formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
> +				SNDRV_PCM_FMTBIT_U16_LE | SNDRV_PCM_FMTBIT_U16_BE |
> +				SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
> +				SNDRV_PCM_FMTBIT_U24_LE | SNDRV_PCM_FMTBIT_U24_BE,
> +			.channels_min = 1,
> +			.channels_max = 2,
> +			.rate_max =     192000,
> +			.rate_min =	8000,
> +		},
> +		.id = USB_RX,
> +		.name = "USB_RX_BE",
> +		.ops = &q6usb_ops,
> +	},
> +};
> +
> +static int q6usb_audio_ports_of_xlate_dai_name(struct snd_soc_component *component,
> +					const struct of_phandle_args *args,
> +					const char **dai_name)
> +{
> +	int id = args->args[0];
> +	int ret = -EINVAL;
> +	int i;
> +
> +	for (i = 0; i  < ARRAY_SIZE(q6usb_be_dais); i++) {
> +		if (q6usb_be_dais[i].id == id) {
> +			*dai_name = q6usb_be_dais[i].name;
> +			ret = 0;
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static int q6usb_alsa_connection_cb(struct snd_soc_usb *usb, int card_idx,
> +			int connected)
> +{
> +	struct snd_soc_dapm_context *dapm;
> +	struct q6usb_port_data *data;
> +
> +	dapm = snd_soc_component_get_dapm(usb->component);
> +	data = dev_get_drvdata(usb->component->dev);
> +
> +	if (connected) {
> +		snd_soc_dapm_enable_pin(dapm, "USB_RX_BE");
> +		/* We only track the latest USB headset plugged in */
> +		data->active_idx = card_idx;
> +	} else {
> +		snd_soc_dapm_disable_pin(dapm, "USB_RX_BE");
> +	}
> +	snd_soc_dapm_sync(dapm);
> +
> +	return 0;
> +}
> +
> +static int q6usb_component_probe(struct snd_soc_component *component)
> +{
> +	struct q6usb_port_data *data = dev_get_drvdata(component->dev);
> +	struct snd_soc_dapm_context *dapm = snd_soc_component_get_dapm(component);
> +
> +	snd_soc_dapm_disable_pin(dapm, "USB_RX_BE");
> +	snd_soc_dapm_sync(dapm);
> +
> +	data->usb = snd_soc_usb_add_port(component->dev, &data->priv, q6usb_alsa_connection_cb);
> +	if (IS_ERR(data->usb)) {
> +		dev_err(component->dev, "failed to add usb port\n");
> +		return -ENODEV;
> +	}
> +
> +	data->usb->component = component;
> +
> +	return 0;
> +}
> +


snd_soc_usb_remove_port should be part of component remove rather than 
platform device remove.

static void q6usb_component_remove(struct snd_soc_component *component)
{
	snd_soc_usb_remove_port(component->dev);
}

and delete q6usb_dai_dev_remove()

> +static const struct snd_soc_component_driver q6usb_dai_component = {
> +	.probe = q6usb_component_probe,
> +	.name = "q6usb-dai-component",
> +	.dapm_widgets = q6usb_dai_widgets,
> +	.num_dapm_widgets = ARRAY_SIZE(q6usb_dai_widgets),
> +	.dapm_routes = q6usb_dapm_routes,
> +	.num_dapm_routes = ARRAY_SIZE(q6usb_dapm_routes),
> +	.of_xlate_dai_name = q6usb_audio_ports_of_xlate_dai_name,
> +};
> +
> +static int q6usb_dai_dev_probe(struct platform_device *pdev)
> +{
> +	struct device_node *node = pdev->dev.of_node;
> +	struct q6usb_port_data *data;
> +	struct device *dev = &pdev->dev;
> +	struct of_phandle_args args;
> +	int ret;
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u32(node, "qcom,usb-audio-intr-num",
> +				&data->priv.intr_num);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to read intr num.\n");
> +		return ret;
> +	}
> +
> +	ret = of_parse_phandle_with_fixed_args(node, "iommus", 1, 0, &args);
> +	if (ret < 0)
> +		data->priv.sid = -1;
> +	else
> +		data->priv.sid = args.args[0] & SID_MASK;
> +
> +	data->priv.domain = iommu_get_domain_for_dev(&pdev->dev);
> +
> +	data->priv.dev = dev;
> +	dev_set_drvdata(dev, data);
> +
> +	ret = devm_snd_soc_register_component(dev, &q6usb_dai_component,
> +					q6usb_be_dais, ARRAY_SIZE(q6usb_be_dais));
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int q6usb_dai_dev_remove(struct platform_device *pdev)
> +{
> +	snd_soc_usb_remove_port(&pdev->dev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id q6usb_dai_device_id[] = {
> +	{ .compatible = "qcom,q6usb-dais" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, q6usb_dai_device_id);
> +
> +static struct platform_driver q6usb_dai_platform_driver = {
> +	.driver = {
> +		.name = "q6usb-dai",
> +		.of_match_table = of_match_ptr(q6usb_dai_device_id),
> +	},
> +	.probe = q6usb_dai_dev_probe,
> +	.remove = q6usb_dai_dev_remove,
> +};
> +module_platform_driver(q6usb_dai_platform_driver);
> +
> +MODULE_DESCRIPTION("Q6 USB backend dai driver");
> +MODULE_LICENSE("GPL");
  

Hi Srinivas,

On 3/9/2023 1:01 AM, Srinivas Kandagatla wrote:
> 
> 
> On 08/03/2023 23:57, Wesley Cheng wrote:
>> Create a USB BE component that will register a new USB port to the 
>> ASoC USB
>> framework.  This will handle determination on if the requested audio
>> profile is supported by the USB device currently selected.
>>
>> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
> 
> Thanks Wesley for the patch, I have few minor comments.
> 

Thanks for the review!

>> ---
>>   include/sound/q6usboffload.h  |  20 ++++
>>   sound/soc/qcom/Kconfig        |   4 +
>>   sound/soc/qcom/qdsp6/Makefile |   1 +
>>   sound/soc/qcom/qdsp6/q6usb.c  | 208 ++++++++++++++++++++++++++++++++++
>>   4 files changed, 233 insertions(+)
>>   create mode 100644 include/sound/q6usboffload.h
>>   create mode 100644 sound/soc/qcom/qdsp6/q6usb.c
>>
>> diff --git a/include/sound/q6usboffload.h b/include/sound/q6usboffload.h
>> new file mode 100644
>> index 000000000000..4fb1912d9f55
>> --- /dev/null
>> +++ b/include/sound/q6usboffload.h
>> @@ -0,0 +1,20 @@
>> +/* SPDX-License-Identifier: GPL-2.0
>> + *
>> + * linux/sound/q6usboffload.h -- QDSP6 USB offload
>> + *
>> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All 
>> rights reserved.
>> + */
>> +
>> +/**
>> + * struct q6usb_offload
>> + * @dev - dev handle to usb be
>> + * @sid - streamID for iommu
>> + * @intr_num - usb interrupter number
>> + * @domain - allocated iommu domain
>> + **/
>> +struct q6usb_offload {
>> +    struct device *dev;
>> +    long long sid;
>> +    u32 intr_num;
>> +    struct iommu_domain *domain;
> Why do we need to store this domain, You can remove this along with the 
> one line that gets domain in probe function.
> 

We'll need a reference to the iommu domain, because the QC USB offload 
driver will be the one that is going to map the XHCI interrupter and 
transfer ring regions for the audio DSP.  This happens when a USB QMI 
enable stream request is received in the USB offload driver.  Please 
refer to:

static int prepare_qmi_response(struct snd_usb_substream *subs,
		struct qmi_uaudio_stream_req_msg_v01 *req_msg,
		struct qmi_uaudio_stream_resp_msg_v01 *resp, int info_idx)
{
...
	xhci_pa = xhci_get_ir_resource(subs->dev, ir);
	if (!xhci_pa) {
		dev_err(uaudio_qdev->dev,
			"failed to get sec event ring address\n");
		ret = -ENODEV;
		goto free_sec_ring;
	}
...
	va = uaudio_iommu_map(MEM_EVENT_RING, dma_coherent, xhci_pa, PAGE_SIZE,
			NULL);
	if (!va) {
		ret = -ENOMEM;
		goto free_sec_ring;
	}

This is just an example for mapping the XHCI secondary interrupter.  We 
will also do the same for the transfer ring.

Thanks
Wesley Cheng
  

On 09/03/2023 19:38, Wesley Cheng wrote:
> Hi Srinivas,
> 
> On 3/9/2023 1:01 AM, Srinivas Kandagatla wrote:
>>
>>
>> On 08/03/2023 23:57, Wesley Cheng wrote:
>>> Create a USB BE component that will register a new USB port to the 
>>> ASoC USB
>>> framework.  This will handle determination on if the requested audio
>>> profile is supported by the USB device currently selected.
>>>
>>> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
>>
>> Thanks Wesley for the patch, I have few minor comments.
>>
> 
> Thanks for the review!
> 
>>> ---
>>>   include/sound/q6usboffload.h  |  20 ++++
>>>   sound/soc/qcom/Kconfig        |   4 +
>>>   sound/soc/qcom/qdsp6/Makefile |   1 +
>>>   sound/soc/qcom/qdsp6/q6usb.c  | 208 ++++++++++++++++++++++++++++++++++
>>>   4 files changed, 233 insertions(+)
>>>   create mode 100644 include/sound/q6usboffload.h
>>>   create mode 100644 sound/soc/qcom/qdsp6/q6usb.c
>>>
>>> diff --git a/include/sound/q6usboffload.h b/include/sound/q6usboffload.h
>>> new file mode 100644
>>> index 000000000000..4fb1912d9f55
>>> --- /dev/null
>>> +++ b/include/sound/q6usboffload.h
>>> @@ -0,0 +1,20 @@
>>> +/* SPDX-License-Identifier: GPL-2.0
>>> + *
>>> + * linux/sound/q6usboffload.h -- QDSP6 USB offload
>>> + *
>>> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All 
>>> rights reserved.
>>> + */
>>> +
>>> +/**
>>> + * struct q6usb_offload
>>> + * @dev - dev handle to usb be
>>> + * @sid - streamID for iommu
>>> + * @intr_num - usb interrupter number
>>> + * @domain - allocated iommu domain
>>> + **/
>>> +struct q6usb_offload {
>>> +    struct device *dev;
>>> +    long long sid;
>>> +    u32 intr_num;
>>> +    struct iommu_domain *domain;
>> Why do we need to store this domain, You can remove this along with 
>> the one line that gets domain in probe function.
>>
> 
> We'll need a reference to the iommu domain, because the QC USB offload 
> driver will be the one that is going to map the XHCI interrupter and 
> transfer ring regions for the audio DSP.  This happens when a USB QMI 

this is okay, AFAIU, as long as uaudio_qdev->dev pointer is used in dma 
alloc apis like dma_map*, dma_alloc_* you would not need to handle 
iommu_domain directly like this in drivers.


--srini

> enable stream request is received in the USB offload driver.  Please 
> refer to:
> 
> static int prepare_qmi_response(struct snd_usb_substream *subs,
>          struct qmi_uaudio_stream_req_msg_v01 *req_msg,
>          struct qmi_uaudio_stream_resp_msg_v01 *resp, int info_idx)
> {
> ...
>      xhci_pa = xhci_get_ir_resource(subs->dev, ir);
>      if (!xhci_pa) {
>          dev_err(uaudio_qdev->dev,
>              "failed to get sec event ring address\n");
>          ret = -ENODEV;
>          goto free_sec_ring;
>      }
> ...
>      va = uaudio_iommu_map(MEM_EVENT_RING, dma_coherent, xhci_pa, 
> PAGE_SIZE,
>              NULL);
>      if (!va) {
>          ret = -ENOMEM;
>          goto free_sec_ring;
>      }
> 
> This is just an example for mapping the XHCI secondary interrupter.  We 
> will also do the same for the transfer ring.
> 
> Thanks
> Wesley Cheng
  

On 09.03.2023 01:57, Wesley Cheng wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Create a USB BE component that will register a new USB port to the ASoC USB
> framework.  This will handle determination on if the requested audio
> profile is supported by the USB device currently selected.
> 
> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
> ---
>  include/sound/q6usboffload.h  |  20 ++++
>  sound/soc/qcom/Kconfig        |   4 +
>  sound/soc/qcom/qdsp6/Makefile |   1 +
>  sound/soc/qcom/qdsp6/q6usb.c  | 208 ++++++++++++++++++++++++++++++++++
>  4 files changed, 233 insertions(+)
>  create mode 100644 include/sound/q6usboffload.h
>  create mode 100644 sound/soc/qcom/qdsp6/q6usb.c
> 

[ ... ]

> +static int q6usb_audio_ports_of_xlate_dai_name(struct snd_soc_component *component,
> +                                       const struct of_phandle_args *args,
> +                                       const char **dai_name)
> +{
> +       int id = args->args[0];
> +       int ret = -EINVAL;
> +       int i;
> +
> +       for (i = 0; i  < ARRAY_SIZE(q6usb_be_dais); i++) {

One extra space here   ^

[ ... ]
  

Hi Srini,

On 3/9/2023 11:21 PM, Srinivas Kandagatla wrote:
> 
> 
> On 09/03/2023 19:38, Wesley Cheng wrote:
>> Hi Srinivas,
>>
>> On 3/9/2023 1:01 AM, Srinivas Kandagatla wrote:
>>>
>>>
>>> On 08/03/2023 23:57, Wesley Cheng wrote:
>>>> Create a USB BE component that will register a new USB port to the 
>>>> ASoC USB
>>>> framework.  This will handle determination on if the requested audio
>>>> profile is supported by the USB device currently selected.
>>>>
>>>> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
>>>
>>> Thanks Wesley for the patch, I have few minor comments.
>>>
>>
>> Thanks for the review!
>>
>>>> ---
>>>>   include/sound/q6usboffload.h  |  20 ++++
>>>>   sound/soc/qcom/Kconfig        |   4 +
>>>>   sound/soc/qcom/qdsp6/Makefile |   1 +
>>>>   sound/soc/qcom/qdsp6/q6usb.c  | 208 
>>>> ++++++++++++++++++++++++++++++++++
>>>>   4 files changed, 233 insertions(+)
>>>>   create mode 100644 include/sound/q6usboffload.h
>>>>   create mode 100644 sound/soc/qcom/qdsp6/q6usb.c
>>>>
>>>> diff --git a/include/sound/q6usboffload.h 
>>>> b/include/sound/q6usboffload.h
>>>> new file mode 100644
>>>> index 000000000000..4fb1912d9f55
>>>> --- /dev/null
>>>> +++ b/include/sound/q6usboffload.h
>>>> @@ -0,0 +1,20 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0
>>>> + *
>>>> + * linux/sound/q6usboffload.h -- QDSP6 USB offload
>>>> + *
>>>> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All 
>>>> rights reserved.
>>>> + */
>>>> +
>>>> +/**
>>>> + * struct q6usb_offload
>>>> + * @dev - dev handle to usb be
>>>> + * @sid - streamID for iommu
>>>> + * @intr_num - usb interrupter number
>>>> + * @domain - allocated iommu domain
>>>> + **/
>>>> +struct q6usb_offload {
>>>> +    struct device *dev;
>>>> +    long long sid;
>>>> +    u32 intr_num;
>>>> +    struct iommu_domain *domain;
>>> Why do we need to store this domain, You can remove this along with 
>>> the one line that gets domain in probe function.
>>>
>>
>> We'll need a reference to the iommu domain, because the QC USB offload 
>> driver will be the one that is going to map the XHCI interrupter and 
>> transfer ring regions for the audio DSP.  This happens when a USB QMI 
> 
> this is okay, AFAIU, as long as uaudio_qdev->dev pointer is used in dma 
> alloc apis like dma_map*, dma_alloc_* you would not need to handle 
> iommu_domain directly like this in drivers.
> 

Was looking into this a bit more, but couldn't figure out the proper DMA 
API that would achieve what we're attempting to do.  So we are trying to 
map the PA of the memory allocated by the XHCI driver, for say...the 
xfer buffers being used for the ISOC ep.

If I call the DMA MAP variants, ie dma_map_single_attrs, we pass in a 
virtual address only, and the DMA map api will map to a PA that it 
derives from that.  However, we're trying to map to memory accessible by 
the audio DSP, which is the virtual address we're passing into 
iommu_map(), and the PA mapping to is the XHCI xfer buffer.  There 
wasn't a similar API that achieved this.  Please clarify if there might 
be something I'm missing.

Thanks
Wesley Cheng