@@ -96,6 +96,22 @@ config USB_GADGET_VBUS_DRAW
This value will be used except for system-specific gadget
drivers that have more specific information.
+config USB_GADGET_STORAGE_NUM_BUFFERS
+ int "Number of storage pipeline buffers"
+ range 2 4
+ default 2
+ help
+ Usually 2 buffers are enough to establish a good buffering
+ pipeline. The number may be increased in order to compensate
+ for a bursty VFS behaviour. For instance there may be cpu wake up
+ latencies that makes the VFS to appear bursty in a system with
+ an cpu on-demand governor. Especially if DMA is doing IO to
+ offload the CPU. In this case the CPU will go into power
+ save often and spin up occasionally to move data within VFS.
+ If selecting USB_DEBUG this value may be set by a module
+ parameter as well.
+ If unsure, say 2.
+
#
# USB Peripheral Controller Support
#
@@ -363,7 +363,6 @@ struct fsg_common {
struct fsg_buffhd *next_buffhd_to_fill;
struct fsg_buffhd *next_buffhd_to_drain;
- struct fsg_buffhd buffhds[FSG_NUM_BUFFERS];
int cmnd_size;
u8 cmnd[MAX_COMMAND_SIZE];
@@ -407,6 +406,8 @@ struct fsg_common {
char inquiry_string[8 + 16 + 4 + 1];
struct kref ref;
+ /* Must be the last entry */
+ struct fsg_buffhd buffhds[0];
};
struct fsg_config {
@@ -2728,12 +2729,15 @@ static struct fsg_common *fsg_common_init(struct fsg_common *common,
/* Allocate? */
if (!common) {
- common = kzalloc(sizeof *common, GFP_KERNEL);
+ common = kzalloc(sizeof(struct fsg_common) +
+ sizeof(struct fsg_buffhd) * FSG_NUM_BUFFERS,
+ GFP_KERNEL);
if (!common)
return ERR_PTR(-ENOMEM);
common->free_storage_on_release = 1;
} else {
- memset(common, 0, sizeof *common);
+ memset(common, 0, sizeof(struct fsg_common) +
+ sizeof(struct fsg_buffhd) * FSG_NUM_BUFFERS);
common->free_storage_on_release = 0;
}
@@ -461,7 +461,6 @@ struct fsg_dev {
struct fsg_buffhd *next_buffhd_to_fill;
struct fsg_buffhd *next_buffhd_to_drain;
- struct fsg_buffhd buffhds[FSG_NUM_BUFFERS];
int thread_wakeup_needed;
struct completion thread_notifier;
@@ -488,6 +487,8 @@ struct fsg_dev {
unsigned int nluns;
struct fsg_lun *luns;
struct fsg_lun *curlun;
+ /* Must be the last entry */
+ struct fsg_buffhd buffhds[0];
};
typedef void (*fsg_routine_t)(struct fsg_dev *);
@@ -3587,7 +3588,9 @@ static int __init fsg_alloc(void)
{
struct fsg_dev *fsg;
- fsg = kzalloc(sizeof *fsg, GFP_KERNEL);
+ fsg = kzalloc(sizeof(struct fsg_dev) +
+ sizeof(struct fsg_buffhd) * FSG_NUM_BUFFERS, GFP_KERNEL);
+
if (!fsg)
return -ENOMEM;
spin_lock_init(&fsg->lock);
@@ -3605,6 +3608,9 @@ static int __init fsg_init(void)
int rc;
struct fsg_dev *fsg;
+ if (!FSG_NUM_BUFFERS_IS_VALID(FSG_NUM_BUFFERS))
+ return -EINVAL;
+
if ((rc = fsg_alloc()) != 0)
return rc;
fsg = the_fsg;
@@ -116,9 +116,8 @@ static int __init msg_do_config(struct usb_configuration *c)
static const struct fsg_operations ops = {
.thread_exits = msg_thread_exits,
};
- static struct fsg_common common;
+ struct fsg_common *common = NULL;
- struct fsg_common *retp;
struct fsg_config config;
int ret;
@@ -130,12 +129,12 @@ static int __init msg_do_config(struct usb_configuration *c)
fsg_config_from_params(&config, &mod_data);
config.ops = &ops;
- retp = fsg_common_init(&common, c->cdev, &config);
- if (IS_ERR(retp))
- return PTR_ERR(retp);
+ common = fsg_common_init(common, c->cdev, &config);
+ if (IS_ERR(common))
+ return PTR_ERR(common);
- ret = fsg_bind_config(c->cdev, c, &common);
- fsg_common_put(&common);
+ ret = fsg_bind_config(c->cdev, c, common);
+ fsg_common_put(common);
return ret;
}
@@ -179,6 +178,9 @@ MODULE_LICENSE("GPL");
static int __init msg_init(void)
{
+ if (!FSG_NUM_BUFFERS_IS_VALID(FSG_NUM_BUFFERS))
+ return -EINVAL;
+
return usb_composite_probe(&msg_driver, msg_bind);
}
module_init(msg_init);
@@ -262,8 +262,24 @@ static struct fsg_lun *fsg_lun_from_dev(struct device *dev)
#define EP0_BUFSIZE 256
#define DELAYED_STATUS (EP0_BUFSIZE + 999) /* An impossibly large value */
-/* Number of buffers we will use. 2 is enough for double-buffering */
-#define FSG_NUM_BUFFERS 2
+#ifdef CONFIG_USB_DEBUG
+
+static unsigned int fsg_num_buffers = CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS;
+module_param(fsg_num_buffers, uint, S_IRUGO);
+MODULE_PARM_DESC(fsg_num_buffers, "Number of pipeline buffers");
+#define FSG_NUM_BUFFERS fsg_num_buffers
+
+#else
+
+/*
+ * Number of buffers we will use.
+ * 2 is usually enough for good buffering pipeline
+ */
+#define FSG_NUM_BUFFERS CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS
+
+#endif /* CONFIG_USB_DEBUG */
+
+#define FSG_NUM_BUFFERS_IS_VALID(num) (num >= 2 && num <= 4 ? true : false)
/* Default size of buffer length. */
#define FSG_BUFLEN ((u32)16384)