ALSA: usb-audio: Restrict rates for the shared clocks

commit 4e7cf1fbb34ecb472c073980458cbe413afd4d64 upstream.

When a single clock source is shared among several endpoints, we have
to keep the same rate on all active endpoints as long as the clock is
being used.  For dealing with such a case, this patch adds one more
check in the hw params constraint for the rate to take the shared
clocks into account.  The current rate is evaluated from the endpoint
list that applies the same clock source.

BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1190418
Link: https://lore.kernel.org/r/20210929080844.11583-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/usb/card.h b/sound/usb/card.h
index 860faaf249ea6bc5f7debd7dd2804eefff0385fb..746a765b2437abdcf8798b2a042116814acd4826 100644 (file)
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -137,6 +137,7 @@ struct snd_usb_endpoint {
        unsigned int cur_period_frames;
        unsigned int cur_period_bytes;
        unsigned int cur_buffer_periods;
+       unsigned char cur_clock;
 
        spinlock_t lock;
        struct list_head list;

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index ba2d7e68842075bdc830c7547633702a704a3087..06241568abf7cf2147cfef4fdbd258331ebb2cbc 100644 (file)
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -726,6 +726,7 @@ snd_usb_endpoint_open(struct snd_usb_audio *chip,
                ep->cur_period_frames = params_period_size(params);
                ep->cur_period_bytes = ep->cur_period_frames * ep->cur_frame_bytes;
                ep->cur_buffer_periods = params_periods(params);
+               ep->cur_clock = fp->clock;
 
                if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
                        endpoint_set_syncinterval(chip, ep);
@@ -837,6 +838,7 @@ void snd_usb_endpoint_close(struct snd_usb_audio *chip,
                ep->altsetting = 0;
                ep->cur_audiofmt = NULL;
                ep->cur_rate = 0;
+               ep->cur_clock = 0;
                ep->iface_ref = NULL;
                usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
        }
@@ -1344,6 +1346,25 @@ unlock:
        return err;
 }
 
+/* get the current rate set to the given clock by any endpoint */
+int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock)
+{
+       struct snd_usb_endpoint *ep;
+       int rate = 0;
+
+       if (!clock)
+               return 0;
+       mutex_lock(&chip->mutex);
+       list_for_each_entry(ep, &chip->ep_list, list) {
+               if (ep->cur_clock == clock && ep->cur_rate) {
+                       rate = ep->cur_rate;
+                       break;
+               }
+       }
+       mutex_unlock(&chip->mutex);
+       return rate;
+}
+
 /**
  * snd_usb_endpoint_start: start an snd_usb_endpoint
  *

diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h
index a668f675b52b0faa58b1b3455738415d0639c59a..a1099ec37e1c96e56284c6009e8271aec59914e1 100644 (file)
--- a/sound/usb/endpoint.h
+++ b/sound/usb/endpoint.h
@@ -19,6 +19,7 @@ void snd_usb_endpoint_close(struct snd_usb_audio *chip,
                            struct snd_usb_endpoint *ep);
 int snd_usb_endpoint_configure(struct snd_usb_audio *chip,
                               struct snd_usb_endpoint *ep);
+int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock);
 
 bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
                                 struct snd_usb_endpoint *ep,

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 5dc9266180e379217520100092e7379e722d5bdc..19392117de9e828e7176d2f958e7fa71619231d3 100644 (file)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -734,6 +734,7 @@ static int hw_rule_rate(struct snd_pcm_hw_params *params,
                        struct snd_pcm_hw_rule *rule)
 {
        struct snd_usb_substream *subs = rule->private;
+       struct snd_usb_audio *chip = subs->stream->chip;
        const struct audioformat *fp;
        struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
        unsigned int rmin, rmax, r;
@@ -745,6 +746,14 @@ static int hw_rule_rate(struct snd_pcm_hw_params *params,
        list_for_each_entry(fp, &subs->fmt_list, list) {
                if (!hw_check_valid_format(subs, params, fp))
                        continue;
+               r = snd_usb_endpoint_get_clock_rate(chip, fp->clock);
+               if (r > 0) {
+                       if (!snd_interval_test(it, r))
+                               continue;
+                       rmin = min(rmin, r);
+                       rmax = max(rmax, r);
+                       continue;
+               }
                if (fp->rate_table && fp->nr_rates) {
                        for (i = 0; i < fp->nr_rates; i++) {
                                r = fp->rate_table[i];