| Message ID | 20221223233200.26089-5-quic_wcheng@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce QC USB SND audio offloading support | expand |
Hi, On Sat, 24 Dec 2022 at 01:33, Wesley Cheng <quic_wcheng@quicinc.com> wrote: > > Allow for different vendors to be notified on USB SND connect/disconnect > seqeunces. This allows for vendor USB SND modules to properly initialize > and populate internal structures with references to the USB SND chip > device. The commit message definitely needs some improvement. We do not notify vendors on SND connect/disconnect events. > > Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com> > --- > sound/usb/card.c | 22 ++++++++++++++++++++++ > sound/usb/card.h | 7 +++++++ > 2 files changed, 29 insertions(+) > > diff --git a/sound/usb/card.c b/sound/usb/card.c > index 26268ffb8274..212f55a7683c 100644 > --- a/sound/usb/card.c > +++ b/sound/usb/card.c > @@ -117,6 +117,21 @@ MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no) > static DEFINE_MUTEX(register_mutex); > static struct snd_usb_audio *usb_chip[SNDRV_CARDS]; > static struct usb_driver usb_audio_driver; > +static struct snd_usb_vendor_ops *vendor_ops; > + > +int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops) platform ops? > +{ > + vendor_ops = ops; > + return 0; > +} > +EXPORT_SYMBOL_GPL(snd_usb_register_vendor_ops); What happens if several platforms try to register different ops? I saw from the patch 09/14 that you register these ops unconditionally. If other devices follow your approach there is an obvious conflict. > + > +int snd_usb_unregister_vendor_ops(void) > +{ > + vendor_ops = NULL; > + return 0; > +} > +EXPORT_SYMBOL_GPL(snd_usb_unregister_vendor_ops); > > /* > * disconnect streams > @@ -910,6 +925,10 @@ static int usb_audio_probe(struct usb_interface *intf, > usb_set_intfdata(intf, chip); > atomic_dec(&chip->active); > mutex_unlock(®ister_mutex); > + > + if (vendor_ops->connect_cb) > + vendor_ops->connect_cb(intf, chip); > + > return 0; > > __error: > @@ -943,6 +962,9 @@ static void usb_audio_disconnect(struct usb_interface *intf) > if (chip == USB_AUDIO_IFACE_UNUSED) > return; > > + if (vendor_ops->disconnect_cb) > + vendor_ops->disconnect_cb(intf); > + > card = chip->card; > > mutex_lock(®ister_mutex); > diff --git a/sound/usb/card.h b/sound/usb/card.h > index 40061550105a..a785bb256b0d 100644 > --- a/sound/usb/card.h > +++ b/sound/usb/card.h > @@ -206,4 +206,11 @@ struct snd_usb_stream { > struct list_head list; > }; > > +struct snd_usb_vendor_ops { > + void (*connect_cb)(struct usb_interface *intf, struct snd_usb_audio *chip); > + void (*disconnect_cb)(struct usb_interface *intf); > +}; > + > +int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops); > +int snd_usb_unregister_vendor_ops(void); > #endif /* __USBAUDIO_CARD_H */ -- With best wishes Dmitry
Hi Dmitry, On 12/24/2022 3:03 AM, Dmitry Baryshkov wrote: > Hi, > > On Sat, 24 Dec 2022 at 01:33, Wesley Cheng <quic_wcheng@quicinc.com> wrote: >> >> Allow for different vendors to be notified on USB SND connect/disconnect >> seqeunces. This allows for vendor USB SND modules to properly initialize >> and populate internal structures with references to the USB SND chip >> device. > > The commit message definitely needs some improvement. We do not notify > vendors on SND connect/disconnect events. > > >> >> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com> >> --- >> sound/usb/card.c | 22 ++++++++++++++++++++++ >> sound/usb/card.h | 7 +++++++ >> 2 files changed, 29 insertions(+) >> >> diff --git a/sound/usb/card.c b/sound/usb/card.c >> index 26268ffb8274..212f55a7683c 100644 >> --- a/sound/usb/card.c >> +++ b/sound/usb/card.c >> @@ -117,6 +117,21 @@ MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no) >> static DEFINE_MUTEX(register_mutex); >> static struct snd_usb_audio *usb_chip[SNDRV_CARDS]; >> static struct usb_driver usb_audio_driver; >> +static struct snd_usb_vendor_ops *vendor_ops; >> + >> +int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops) > > platform ops? > Will change it. >> +{ >> + vendor_ops = ops; >> + return 0; >> +} >> +EXPORT_SYMBOL_GPL(snd_usb_register_vendor_ops); > > What happens if several platforms try to register different ops? I saw > from the patch 09/14 that you register these ops unconditionally. If > other devices follow your approach there is an obvious conflict. > Thank you for the review. That is true. I don't think there is a proper need to have multiple vendor ops being registered, so maybe just returning an error for if ops are already registered is sufficient. Thanks Wesley Cheng
On 27/12/2022 23:07, Wesley Cheng wrote: > Hi Dmitry, > > On 12/24/2022 3:03 AM, Dmitry Baryshkov wrote: >> Hi, >> >> On Sat, 24 Dec 2022 at 01:33, Wesley Cheng <quic_wcheng@quicinc.com> >> wrote: >>> >>> Allow for different vendors to be notified on USB SND connect/disconnect >>> seqeunces. This allows for vendor USB SND modules to properly >>> initialize >>> and populate internal structures with references to the USB SND chip >>> device. >> >> The commit message definitely needs some improvement. We do not notify >> vendors on SND connect/disconnect events. >> >> >>> >>> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com> >>> --- >>> sound/usb/card.c | 22 ++++++++++++++++++++++ >>> sound/usb/card.h | 7 +++++++ >>> 2 files changed, 29 insertions(+) >>> >>> diff --git a/sound/usb/card.c b/sound/usb/card.c >>> index 26268ffb8274..212f55a7683c 100644 >>> --- a/sound/usb/card.c >>> +++ b/sound/usb/card.c >>> @@ -117,6 +117,21 @@ MODULE_PARM_DESC(skip_validation, "Skip unit >>> descriptor validation (default: no) >>> static DEFINE_MUTEX(register_mutex); >>> static struct snd_usb_audio *usb_chip[SNDRV_CARDS]; >>> static struct usb_driver usb_audio_driver; >>> +static struct snd_usb_vendor_ops *vendor_ops; >>> + >>> +int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops) >> >> platform ops? >> > > Will change it. > >>> +{ >>> + vendor_ops = ops; >>> + return 0; >>> +} >>> +EXPORT_SYMBOL_GPL(snd_usb_register_vendor_ops); >> >> What happens if several platforms try to register different ops? I saw >> from the patch 09/14 that you register these ops unconditionally. If >> other devices follow your approach there is an obvious conflict. >> > > Thank you for the review. > > That is true. I don't think there is a proper need to have multiple > vendor ops being registered, so maybe just returning an error for if ops > are already registered is sufficient. This would be a required step. And also you have to check the running platform before registering your ops unconditionally. Ideally this should be done as a part of the device's driver, so that we can control registration of the platform ops using the usual interface. > > Thanks > Wesley Cheng
On 24.12.22 00:31, Wesley Cheng wrote: > Allow for different vendors to be notified on USB SND connect/disconnect > seqeunces. This allows for vendor USB SND modules to properly initialize > and populate internal structures with references to the USB SND chip > device. Hi, this raises a design question. If the system is suspending or, worse, hibernating, how do you make sure the offloader and the device are suspended in the correct order? And what happens if you need to go into reset_resume() when resuming? Regards Oliver
On Thu, 29 Dec 2022 14:49:21 +0100, Oliver Neukum wrote: > > > > On 24.12.22 00:31, Wesley Cheng wrote: > > Allow for different vendors to be notified on USB SND connect/disconnect > > seqeunces. This allows for vendor USB SND modules to properly initialize > > and populate internal structures with references to the USB SND chip > > device. > > Hi, > > this raises a design question. If the system is suspending or, worse, > hibernating, how do you make sure the offloader and the device are > suspended in the correct order? > And what happens if you need to go into reset_resume() when resuming? I guess we'd need to establish a device link when the binding from the offload driver is done. Then the PM order will be assured. Takashi
Hi, On 12/29/2022 6:20 AM, Takashi Iwai wrote: > On Thu, 29 Dec 2022 14:49:21 +0100, > Oliver Neukum wrote: >> >> >> >> On 24.12.22 00:31, Wesley Cheng wrote: >>> Allow for different vendors to be notified on USB SND connect/disconnect >>> seqeunces. This allows for vendor USB SND modules to properly initialize >>> and populate internal structures with references to the USB SND chip >>> device. >> >> Hi, >> >> this raises a design question. If the system is suspending or, worse, >> hibernating, how do you make sure the offloader and the device are >> suspended in the correct order? >> And what happens if you need to go into reset_resume() when resuming? It may depend on how the offloading is implemented, but we do have a mechanism to force the audio stream off from the qc_usb_audio_offload. Regardless of if the UDEV is suspended first, or the USB backend, as long as we ensure that the offloading is disabled before entering suspend, I think that should be sufficient. I would need to add some suspend handling in the offload driver to issue the command to stop the offloading. As for the resume path, is there a concern if either device is resumed first? The only scenario where maybe it could cause some mishandling is if the USB backend is resumed before the offload driver is connected/resumed. This means that the userspace ALSA would have access to the platform sound card, and could potentially attempt to route audio streams to it. I think in worst case, if we were going through a reset_resume() we would end up rejecting that request coming from the audio DSP to enable the stream. However, userspace entities would be resumed/unfrozen last, so not sure if that would ever be a problem. The reset_resume() path is fine. Bus reset is going to cause a disconnect() callback in the offload driver, in which we already have the proper handling for ensuring the offload path is halted, and we reject any incoming stream start requests. Thanks Wesley Cheng
On 30.12.22 08:10, Wesley Cheng wrote: > It may depend on how the offloading is implemented, but we do have a mechanism to force the audio stream off from the qc_usb_audio_offload. Regardless of if the UDEV is suspended first, or the USB backend, as long as we ensure that the offloading is disabled before entering suspend, I think that should be sufficient. You would presumably output garbage, if the UDEV is asleep but the backend is not. > The reset_resume() path is fine. Bus reset is going to cause a disconnect() callback in the offload driver, in which we already have the proper handling for ensuring the offload path is halted, and we reject any incoming stream start requests. How? If we go the reset_resume() code path, we find that usb-audio does not make a difference between regular resume() and reset_resume() Regards Oliver
diff --git a/sound/usb/card.c b/sound/usb/card.c index 26268ffb8274..212f55a7683c 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -117,6 +117,21 @@ MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no) static DEFINE_MUTEX(register_mutex); static struct snd_usb_audio *usb_chip[SNDRV_CARDS]; static struct usb_driver usb_audio_driver; +static struct snd_usb_vendor_ops *vendor_ops; + +int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops) +{ + vendor_ops = ops; + return 0; +} +EXPORT_SYMBOL_GPL(snd_usb_register_vendor_ops); + +int snd_usb_unregister_vendor_ops(void) +{ + vendor_ops = NULL; + return 0; +} +EXPORT_SYMBOL_GPL(snd_usb_unregister_vendor_ops); /* * disconnect streams @@ -910,6 +925,10 @@ static int usb_audio_probe(struct usb_interface *intf, usb_set_intfdata(intf, chip); atomic_dec(&chip->active); mutex_unlock(®ister_mutex); + + if (vendor_ops->connect_cb) + vendor_ops->connect_cb(intf, chip); + return 0; __error: @@ -943,6 +962,9 @@ static void usb_audio_disconnect(struct usb_interface *intf) if (chip == USB_AUDIO_IFACE_UNUSED) return; + if (vendor_ops->disconnect_cb) + vendor_ops->disconnect_cb(intf); + card = chip->card; mutex_lock(®ister_mutex); diff --git a/sound/usb/card.h b/sound/usb/card.h index 40061550105a..a785bb256b0d 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -206,4 +206,11 @@ struct snd_usb_stream { struct list_head list; }; +struct snd_usb_vendor_ops { + void (*connect_cb)(struct usb_interface *intf, struct snd_usb_audio *chip); + void (*disconnect_cb)(struct usb_interface *intf); +}; + +int snd_usb_register_vendor_ops(struct snd_usb_vendor_ops *ops); +int snd_usb_unregister_vendor_ops(void); #endif /* __USBAUDIO_CARD_H */
Allow for different vendors to be notified on USB SND connect/disconnect seqeunces. This allows for vendor USB SND modules to properly initialize and populate internal structures with references to the USB SND chip device. Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com> --- sound/usb/card.c | 22 ++++++++++++++++++++++ sound/usb/card.h | 7 +++++++ 2 files changed, 29 insertions(+)