Re: [RFC PATCH 03/14] ASoC: qcom: Add USB backend ASoC driver for Q6

Wesley Cheng
2022-12-27T21:11:05Z

Hi Greg,

On 12/24/2022 1:02 AM, Greg KH wrote:
> On Fri, Dec 23, 2022 at 03:31:49PM -0800, 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>
>> ---
>> include/sound/q6usboffload.h | 20 +++
>> sound/soc/qcom/Kconfig | 4 +
>> sound/soc/qcom/qdsp6/Makefile | 1 +
>> sound/soc/qcom/qdsp6/q6usb.c | 232 ++++++++++++++++++++++++++++++++++
>> 4 files changed, 257 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..e576808901d9
>> --- /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 Qualcomm Innovation Center, Inc. All rights reserved.
>> + */
>> +
>> +/**
>> + * struct q6usb_offload
>> + * @dev - dev handle to usb be
>
> "be"? What is that?
>
>> + * @sid - streamID for iommu
>> + * @intr_num - usb interrupter number
>> + * @domain - allocated iommu domain
>> + **/
>> +struct q6usb_offload {
>> + struct device *dev;
>
> Do you properly reference count this?
>
>> + u32 sid;
>> + u32 intr_num;
>> + struct iommu_domain *domain;
>> +};
>
> What is the lifetime of this structure? Who owns it? Where is the lock
> for accessing it?
>

Owner of this structure is the USB backend. If the USB backend is
removed, then the qc_audio_offload driver would never receive the QMI
request to enable the audio stream path from the audio dsp. (where this
is referenced) It will exist as long as the USB BE device exists.

One thing I will need to follow up on is if an ASoC backend device is
removed while an audio playback is happening how it would handle it.

>> diff --git a/sound/soc/qcom/Kconfig b/sound/soc/qcom/Kconfig
>> index 8c7398bc1ca8..d65c365116e5 100644
>> --- a/sound/soc/qcom/Kconfig
>> +++ b/sound/soc/qcom/Kconfig
>> @@ -111,6 +111,9 @@ 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
>> @@ -131,6 +134,7 @@ 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..a9da6dec6c6f
>> --- /dev/null
>> +++ b/sound/soc/qcom/qdsp6/q6usb.c
>> @@ -0,0 +1,232 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
>
> All of the code in this patch series is older than 2022 as I know it has
> been in shipping devices for many years. Please use the proper
> copyright year to make your lawyers happy...
>
>> + */
>> +
>> +#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>
>> +
>> +#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"
>> +
>> +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"},
>> +};
>
> No terminating entry? How does this not break? Why do you need to
> specify the size of the array, that feels like a design bug somewhere.
>
>
>> +
>> +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,
>> + },
>> +};
>> +
>> +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_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);
>> +
>> + data->usb->component = component;
>> +
>> + snd_soc_dapm_disable_pin(dapm, "USB_RX_BE");
>> + snd_soc_dapm_sync(dapm);
>> +
>> + return 0;
>> +}
>> +
>> +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,
>> +};
>> +
>> +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;
>> +
>> + if (!usb->component)
>> + return 0;
>
> How can this happen?
>
> Why is this not an error?
>

If the ASoC platform card that this USB BE is a child of, is not yet
registered then the component probe hasn't happened. However, that is
independent of when the USB connect/disconnect events can happen.

>> +
>> + 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_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;
>> + int ret;
>> +
>> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> + if (!data)
>> + return -ENOMEM;
>> +
>> + ret = of_property_read_u32(node, "qcom,usb-audio-stream-id",
>> + &data->priv.sid);
>> + if (ret) {
>> + dev_err(&pdev->dev, "failed to read sid.\n");
>> + return -ENODEV;
>> + }
>> +
>> + 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 -ENODEV;
>> + }
>> +
>> + data->priv.domain = iommu_domain_alloc(pdev->dev.bus);
>> + if (!data->priv.domain) {
>> + dev_err(&pdev->dev, "failed to allocate iommu domain\n");
>> + return -ENODEV;
>> + }
>> +
>> + /* attach to external processor iommu */
>> + ret = iommu_attach_device(data->priv.domain, &pdev->dev);
>> + if (ret) {
>> + dev_err(&pdev->dev, "failed to attach device ret = %d\n", ret);
>> + goto free_domain;
>> + }
>> +
>> + data->usb = snd_soc_usb_add_port(dev, q6usb_alsa_connection_cb);
>> + if (IS_ERR(data->usb)) {
>> + dev_err(&pdev->dev, "failed to add usb port\n");
>> + goto detach_device;
>> + }
>> +
>> + data->priv.dev = dev;
>> + dev_set_drvdata(dev, data);
>> + devm_snd_soc_register_component(dev, &q6usb_dai_component,
>> + q6usb_be_dais, ARRAY_SIZE(q6usb_be_dais));
>
> Very odd indentation. Please do this properly everywhere.
>
>

Got it...will fix everywhere

>> + snd_soc_usb_set_priv_data(&data->priv);
>> +
>> + return 0;
>> +
>> +detach_device:
>> + iommu_detach_device(data->priv.domain, &pdev->dev);
>> +free_domain:
>> + iommu_domain_free(data->priv.domain);
>> +
>> + return ret;
>> +}
>> +
>> +static int q6usb_dai_dev_remove(struct platform_device *pdev)
>> +{
>> + struct q6usb_port_data *data = platform_get_drvdata(pdev);
>> +
>> + iommu_detach_device(data->priv.domain, &pdev->dev);
>> + iommu_domain_free(data->priv.domain);
>> +
>> + snd_soc_usb_remove_port();
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_OF
>
> Is this really needed still?
>

Will remove this

Thanks
Wesley Cheng