ALSA: usb-audio - Cache mixer values

Cache mixer values in usb-audio driver to reduce too excessive
accesses to the hardware.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 70 insertions, 52 deletions

diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c
index 00397c8a765b..c07b3f8485e3 100644
--- a/sound/usb/usbmixer.c
+++ b/sound/usb/usbmixer.c
@@ -110,6 +110,8 @@ struct mixer_build {
         const struct usbmix_selector_map *selector_map;
 };
 
+#define MAX_CHANNELS    10      /* max logical channels */
+
 struct usb_mixer_elem_info {
         struct usb_mixer_interface *mixer;
         struct usb_mixer_elem_info *next_id_elem; /* list of controls with same id */
@@ -120,6 +122,8 @@ struct usb_mixer_elem_info {
         int channels;
         int val_type;
         int min, max, res;
+        int cached;
+        int cache_val[MAX_CHANNELS];
         u8 initialized;
 };
 
@@ -181,8 +185,6 @@ enum {
         USB_PROC_DCR_RELEASE = 6,
 };
 
-#define MAX_CHANNELS    10      /* max logical channels */
-
 
 /*
  * manual mapping of mixer names
@@ -376,11 +378,35 @@ static int get_cur_ctl_value(struct usb_mixer_elem_info *cval, int validx, int *
 }
 
 /* channel = 0: master, 1 = first channel */
-static inline int get_cur_mix_value(struct usb_mixer_elem_info *cval, int channel, int *value)
+static inline int get_cur_mix_raw(struct usb_mixer_elem_info *cval,
+                                  int channel, int *value)
 {
         return get_ctl_value(cval, GET_CUR, (cval->control << 8) | channel, value);
 }
 
+static int get_cur_mix_value(struct usb_mixer_elem_info *cval,
+                             int channel, int index, int *value)
+{
+        int err;
+
+        if (cval->cached & (1 << channel)) {
+                *value = cval->cache_val[index];
+                return 0;
+        }
+        err = get_cur_mix_raw(cval, channel, value);
+        if (err < 0) {
+                if (!cval->mixer->ignore_ctl_error)
+                        snd_printd(KERN_ERR "cannot get current value for "
+                                   "control %d ch %d: err = %d\n",
+                                   cval->control, channel, err);
+                return err;
+        }
+        cval->cached |= 1 << channel;
+        cval->cache_val[index] = *value;
+        return 0;
+}
+
+
 /*
  * set a mixer value
  */
@@ -412,9 +438,17 @@ static int set_cur_ctl_value(struct usb_mixer_elem_info *cval, int validx, int v
         return set_ctl_value(cval, SET_CUR, validx, value);
 }
 
-static inline int set_cur_mix_value(struct usb_mixer_elem_info *cval, int channel, int value)
+static int set_cur_mix_value(struct usb_mixer_elem_info *cval, int channel,
+                             int index, int value)
 {
-        return set_ctl_value(cval, SET_CUR, (cval->control << 8) | channel, value);
+        int err;
+        err = set_ctl_value(cval, SET_CUR, (cval->control << 8) | channel,
+                            value);
+        if (err < 0)
+                return err;
+        cval->cached |= 1 << channel;
+        cval->cache_val[index] = value;
+        return 0;
 }
 
 /*
@@ -718,7 +752,7 @@ static int get_min_max(struct usb_mixer_elem_info *cval, int default_min)
                 if (cval->min + cval->res < cval->max) {
                         int last_valid_res = cval->res;
                         int saved, test, check;
-                        get_cur_mix_value(cval, minchn, &saved);
+                        get_cur_mix_raw(cval, minchn, &saved);
                         for (;;) {
                                 test = saved;
                                 if (test < cval->max)
@@ -726,8 +760,8 @@ static int get_min_max(struct usb_mixer_elem_info *cval, int default_min)
                                 else
                                         test -= cval->res;
                                 if (test < cval->min || test > cval->max ||
-                                    set_cur_mix_value(cval, minchn, test) ||
-                                    get_cur_mix_value(cval, minchn, &check)) {
+                                    set_cur_mix_value(cval, minchn, 0, test) ||
+                                    get_cur_mix_raw(cval, minchn, &check)) {
                                         cval->res = last_valid_res;
                                         break;
                                 }
@@ -735,7 +769,7 @@ static int get_min_max(struct usb_mixer_elem_info *cval, int default_min)
                                         break;
                                 cval->res *= 2;
                         }
-                        set_cur_mix_value(cval, minchn, saved);
+                        set_cur_mix_value(cval, minchn, 0, saved);
                 }
 
                 cval->initialized = 1;
@@ -775,35 +809,25 @@ static int mixer_ctl_feature_get(struct snd_kcontrol *kcontrol, struct snd_ctl_e
         struct usb_mixer_elem_info *cval = kcontrol->private_data;
         int c, cnt, val, err;
 
+        ucontrol->value.integer.value[0] = cval->min;
         if (cval->cmask) {
                 cnt = 0;
                 for (c = 0; c < MAX_CHANNELS; c++) {
-                        if (cval->cmask & (1 << c)) {
-                                err = get_cur_mix_value(cval, c + 1, &val);
-                                if (err < 0) {
-                                        if (cval->mixer->ignore_ctl_error) {
-                                                ucontrol->value.integer.value[0] = cval->min;
-                                                return 0;
-                                        }
-                                        snd_printd(KERN_ERR "cannot get current value for control %d ch %d: err = %d\n", cval->control, c + 1, err);
-                                        return err;
-                                }
-                                val = get_relative_value(cval, val);
-                                ucontrol->value.integer.value[cnt] = val;
-                                cnt++;
-                        }
+                        if (!(cval->cmask & (1 << c)))
+                                continue;
+                        err = get_cur_mix_value(cval, c + 1, cnt, &val);
+                        if (err < 0)
+                                return cval->mixer->ignore_ctl_error ? 0 : err;
+                        val = get_relative_value(cval, val);
+                        ucontrol->value.integer.value[cnt] = val;
+                        cnt++;
                 }
+                return 0;
         } else {
                 /* master channel */
-                err = get_cur_mix_value(cval, 0, &val);
-                if (err < 0) {
-                        if (cval->mixer->ignore_ctl_error) {
-                                ucontrol->value.integer.value[0] = cval->min;
-                                return 0;
-                        }
-                        snd_printd(KERN_ERR "cannot get current value for control %d master ch: err = %d\n", cval->control, err);
-                        return err;
-                }
+                err = get_cur_mix_value(cval, 0, 0, &val);
+                if (err < 0)
+                        return cval->mixer->ignore_ctl_error ? 0 : err;
                 val = get_relative_value(cval, val);
                 ucontrol->value.integer.value[0] = val;
         }
@@ -820,34 +844,28 @@ static int mixer_ctl_feature_put(struct snd_kcontrol *kcontrol, struct snd_ctl_e
         if (cval->cmask) {
                 cnt = 0;
                 for (c = 0; c < MAX_CHANNELS; c++) {
-                        if (cval->cmask & (1 << c)) {
-                                err = get_cur_mix_value(cval, c + 1, &oval);
-                                if (err < 0) {
-                                        if (cval->mixer->ignore_ctl_error)
-                                                return 0;
-                                        return err;
-                                }
-                                val = ucontrol->value.integer.value[cnt];
-                                val = get_abs_value(cval, val);
-                                if (oval != val) {
-                                        set_cur_mix_value(cval, c + 1, val);
-                                        changed = 1;
-                                }
-                                get_cur_mix_value(cval, c + 1, &val);
-                                cnt++;
+                        if (!(cval->cmask & (1 << c)))
+                                continue;
+                        err = get_cur_mix_value(cval, c + 1, cnt, &oval);
+                        if (err < 0)
+                                return cval->mixer->ignore_ctl_error ? 0 : err;
+                        val = ucontrol->value.integer.value[cnt];
+                        val = get_abs_value(cval, val);
+                        if (oval != val) {
+                                set_cur_mix_value(cval, c + 1, cnt, val);
+                                changed = 1;
                         }
+                        cnt++;
                 }
         } else {
                 /* master channel */
-                err = get_cur_mix_value(cval, 0, &oval);
-                if (err < 0 && cval->mixer->ignore_ctl_error)
-                        return 0;
+                err = get_cur_mix_value(cval, 0, 0, &oval);
                 if (err < 0)
-                        return err;
+                        return cval->mixer->ignore_ctl_error ? 0 : err;
                 val = ucontrol->value.integer.value[0];
                 val = get_abs_value(cval, val);
                 if (val != oval) {
-                        set_cur_mix_value(cval, 0, val);
+                        set_cur_mix_value(cval, 0, 0, val);
                         changed = 1;
                 }
         }