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Date: Fri, 03 Feb 2017 10:58:08 +0530
From: Satendra Singh Thakur <satendra.t@...sung.com>
To: alsa-devel@...a-project.org
Cc: perex@...ex.cz, tiwai@...e.com, o-takashi@...amocchi.jp,
linux-kernel@...r.kernel.org, hemanshu.s@...sung.com,
nishant.s4@...sung.com,
satendra singh thakur <satendra.t@...sung.com>
Subject: [RFC v2] [ALSA][CONTROL] 1. Added 2 ioctls for reading/writing values
of multiple controls in one go (at once) 2. Restructured the code for
read/write of a single control
From: satendra singh thakur <satendra.t@...sung.com>
1.Added 2 ioctls in alsa driver's control interface
-Added an ioctl to read values of multiple elements at once
-Added an ioctl to write values of multiple elements at once
-In the absence of above ioctls user needs to call N ioctls to
read/write value of N elements which requires N context switches
-Proposed ioctls will allow accessing N elements' values in a single
context switch
-Above mentioned ioctl will be useful for alsa utils such as amixer
which reads all controls of given sound card
2. Restructured/Combined two functions snd_ctl_elem_read_user and
snd_ctl_elem_write_user into a single function snd_ctl_elem_rw_user
-These functions were having most of the code which was similar
to each other
-Thus, there was redundant/duplicate code which was removed
and a single function was formed/defined.
-Removed functions snd_ctl_elem_read_user and snd_ctl_elem_write_user
having redundant/duplicate code
3. This is version 2 of RFC, here we combine previous 2 patches
submitted yesterday (02-Feb) with prefix [RFC] [ALSA][CONTROL]
-Fixed doxygen comments related warnings
-Fixed stack frame related warning
Signed-off-by: Satendra Singh Thakur <satendra.t@...sung.com>
---
include/uapi/sound/asound.h | 8 +++
sound/core/control.c | 130 +++++++++++++++++++++++++++++++++----------
2 files changed, 109 insertions(+), 29 deletions(-)
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index be353a7..a0dcee7 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -948,6 +948,11 @@ struct snd_ctl_tlv {
unsigned int length; /* in bytes aligned to 4 */
unsigned int tlv[0]; /* first TLV */
};
+/*Struct to read/write multiple element values */
+struct snd_ctl_elem_values {
+ unsigned int num_vals;/* Number of values*/
+ struct snd_ctl_elem_value *pvals;/* Pointer to the array of values */
+};
#define SNDRV_CTL_IOCTL_PVERSION _IOR('U', 0x00, int)
#define SNDRV_CTL_IOCTL_CARD_INFO _IOR('U', 0x01, struct snd_ctl_card_info)
@@ -974,6 +979,9 @@ struct snd_ctl_tlv {
#define SNDRV_CTL_IOCTL_RAWMIDI_PREFER_SUBDEVICE _IOW('U', 0x42, int)
#define SNDRV_CTL_IOCTL_POWER _IOWR('U', 0xd0, int)
#define SNDRV_CTL_IOCTL_POWER_STATE _IOR('U', 0xd1, int)
+/*Multipe controls' values read and write*/
+#define SNDRV_CTL_IOCTL_ELEMS_READ _IOWR('U', 0xe0, struct snd_ctl_elem_values)
+#define SNDRV_CTL_IOCTL_ELEMS_WRITE _IOWR('U', 0xe1, struct snd_ctl_elem_values)
/*
* Read interface.
diff --git a/sound/core/control.c b/sound/core/control.c
index fb096cb..980046c 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -920,27 +920,6 @@ static int snd_ctl_elem_read(struct snd_card *card,
return result;
}
-static int snd_ctl_elem_read_user(struct snd_card *card,
- struct snd_ctl_elem_value __user *_control)
-{
- struct snd_ctl_elem_value *control;
- int result;
-
- control = memdup_user(_control, sizeof(*control));
- if (IS_ERR(control))
- return PTR_ERR(control);
-
- snd_power_lock(card);
- result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
- if (result >= 0)
- result = snd_ctl_elem_read(card, control);
- snd_power_unlock(card);
- if (result >= 0)
- if (copy_to_user(_control, control, sizeof(*control)))
- result = -EFAULT;
- kfree(control);
- return result;
-}
static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
struct snd_ctl_elem_value *control)
@@ -976,22 +955,38 @@ static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
return result;
}
-static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
- struct snd_ctl_elem_value __user *_control)
+/**
+ * snd_ctl_elem_rw_user - Read/write value of an element
+ * @file: pointer to control file object
+ * @_control: user pointer to struct snd_ctl_elem_value
+ * @write_flag: flag, true for write, false for read operation
+ *
+ * This function reads the value of controls with the given IDs
+ * of the same card
+ * Return: On success, it returns positive number returned by
+ * snd_ctl_elem_write/snd_ctl_elem_read
+ * On failure, it returns appropriate error
+ */
+
+static int snd_ctl_elem_rw_user(struct snd_ctl_file *file,
+ struct snd_ctl_elem_value __user *_control,
+ bool write_flag)
{
struct snd_ctl_elem_value *control;
struct snd_card *card;
int result;
-
control = memdup_user(_control, sizeof(*control));
if (IS_ERR(control))
return PTR_ERR(control);
-
card = file->card;
snd_power_lock(card);
result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
- if (result >= 0)
- result = snd_ctl_elem_write(card, file, control);
+ if (result >= 0) {
+ if (write_flag == true)
+ result = snd_ctl_elem_write(card, file, control);
+ else
+ result = snd_ctl_elem_read(card, control);
+ }
snd_power_unlock(card);
if (result >= 0)
if (copy_to_user(_control, control, sizeof(*control)))
@@ -1000,6 +995,79 @@ static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
return result;
}
+/**
+ * snd_ctl_elems_rw_user - Read/Write values of more than one element,
+ * one by one
+ * @file: pointer to control file object
+ * @pucontrols: user-space pointer to struct snd_ctl_elem_values
+ * @write_flag: this flag distinguises write or read type request
+ *
+ * This function reads/writes the value of controls with the given IDs
+ * of the same card
+ * Return: On full/partial success, It returns number of successful
+ * controls read/written.
+ * On failure, it returns appropriate error
+ */
+static int snd_ctl_elems_rw_user(struct snd_ctl_file *file,
+ struct snd_ctl_elem_values __user *pucontrols,
+ bool write_flag)
+{
+ struct snd_ctl_elem_values controls;
+ struct snd_ctl_elem_value *pcontrol;
+ struct snd_ctl_elem_value __user *puvals;
+ struct snd_card *card;
+ int result;
+ int vals;
+ int controls_count = 0;
+
+ if (copy_from_user(&controls, pucontrols, sizeof(controls)))
+ return -EFAULT;
+ card = file->card;
+ if (!controls.num_vals || controls.num_vals > card->controls_count)
+ return -EINVAL;
+ /*assign user-space pointer**/
+ puvals = (struct snd_ctl_elem_value __user *) controls.pvals;
+ /**allocate memory to pcontrol*/
+ pcontrol = kmalloc(sizeof(*pcontrol), GFP_KERNEL);
+ if (!pcontrol)
+ return -ENOMEM;
+ for (vals = 0; vals < controls.num_vals; vals++) {
+ if (copy_from_user(pcontrol, puvals + vals, sizeof(*pcontrol)))
+ goto exit_err;
+ snd_power_lock(card);
+ result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
+ if (result >= 0) {
+ if (write_flag == true)
+ result = snd_ctl_elem_write(card, file,
+ pcontrol);
+ else
+ result = snd_ctl_elem_read(card, pcontrol);
+ }
+ snd_power_unlock(card);
+ if (result < 0) {
+ /**If control failed to set/get
+ * inform user by sending back -1 in reserved field
+ * so that one can try again for failed elements
+ */
+ pcontrol->reserved[0] = (unsigned char) -1;
+ pr_err("ALSA: control: snd_ctl_elem_write/read failed\
+ for control name = %s\n", pcontrol->id.name);
+ } else {
+ controls_count++;
+ }
+ if (copy_to_user(puvals + vals, pcontrol, sizeof(*pcontrol)))
+ goto exit_err;
+ }
+ pr_debug("ALSA: control: Num values successfully read/written %u\n",\
+ controls_count);
+ kfree(pcontrol);
+ /**Return successful control count to user**/
+ return controls_count;
+exit_err:
+ kfree(pcontrol);
+ return -EFAULT;
+}
+
static int snd_ctl_elem_lock(struct snd_ctl_file *file,
struct snd_ctl_elem_id __user *_id)
{
@@ -1514,9 +1582,13 @@ static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg
case SNDRV_CTL_IOCTL_ELEM_INFO:
return snd_ctl_elem_info_user(ctl, argp);
case SNDRV_CTL_IOCTL_ELEM_READ:
- return snd_ctl_elem_read_user(card, argp);
+ return snd_ctl_elem_rw_user(ctl, argp, false);
+ case SNDRV_CTL_IOCTL_ELEMS_READ:
+ return snd_ctl_elems_rw_user(ctl, argp, false);
case SNDRV_CTL_IOCTL_ELEM_WRITE:
- return snd_ctl_elem_write_user(ctl, argp);
+ return snd_ctl_elem_rw_user(ctl, argp, true);
+ case SNDRV_CTL_IOCTL_ELEMS_WRITE:
+ return snd_ctl_elems_rw_user(ctl, argp, true);
case SNDRV_CTL_IOCTL_ELEM_LOCK:
return snd_ctl_elem_lock(ctl, argp);
case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
--
1.7.9.5
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