bam_dmux: Adapt RX timer interval to data rate.
Instead of always sleeping for 950 to 1050
microseconds between subsequent reads of the
BAM RX pipe, allow the driver to pick an
interval based on how full the BAM pipe is.
Using this technique allows the CPU to stay
in an idle state longer than with just 1ms
sleeps without compromising performance.
Change-Id: I996cd3a9da912a0acc5552566a093d3904cec4e7
Signed-off-by: Anurag Singh <anursing@codeaurora.org>
diff --git a/arch/arm/mach-msm/bam_dmux.c b/arch/arm/mach-msm/bam_dmux.c
index b35e949..04e751a 100644
--- a/arch/arm/mach-msm/bam_dmux.c
+++ b/arch/arm/mach-msm/bam_dmux.c
@@ -47,16 +47,29 @@
#define BAM_MUX_HDR_CMD_STATUS 3 /* unused */
#define BAM_MUX_HDR_CMD_OPEN_NO_A2_PC 4
-#define POLLING_MIN_SLEEP 950 /* 0.95 ms */
-#define POLLING_MAX_SLEEP 1050 /* 1.05 ms */
-#define POLLING_INACTIVITY 40 /* cycles before switch to intr mode */
#define LOW_WATERMARK 2
#define HIGH_WATERMARK 4
+#define DEFAULT_POLLING_MIN_SLEEP (950)
+#define MAX_POLLING_SLEEP (6050)
+#define MIN_POLLING_SLEEP (950)
static int msm_bam_dmux_debug_enable;
module_param_named(debug_enable, msm_bam_dmux_debug_enable,
int, S_IRUGO | S_IWUSR | S_IWGRP);
+static int POLLING_MIN_SLEEP = 950;
+module_param_named(min_sleep, POLLING_MIN_SLEEP,
+ int, S_IRUGO | S_IWUSR | S_IWGRP);
+static int POLLING_MAX_SLEEP = 1050;
+module_param_named(max_sleep, POLLING_MAX_SLEEP,
+ int, S_IRUGO | S_IWUSR | S_IWGRP);
+static int POLLING_INACTIVITY = 40;
+module_param_named(inactivity, POLLING_INACTIVITY,
+ int, S_IRUGO | S_IWUSR | S_IWGRP);
+static int bam_adaptive_timer_enabled = 1;
+module_param_named(adaptive_timer_enabled,
+ bam_adaptive_timer_enabled,
+ int, S_IRUGO | S_IWUSR | S_IWGRP);
#if defined(DEBUG)
static uint32_t bam_dmux_read_cnt;
@@ -177,6 +190,7 @@
static int bam_mux_initialized;
static int polling_mode;
+static unsigned long rx_timer_interval;
static LIST_HEAD(bam_rx_pool);
static DEFINE_MUTEX(bam_rx_pool_mutexlock);
@@ -1116,6 +1130,7 @@
struct rx_pkt_info *info;
int inactive_cycles = 0;
int ret;
+ u32 buffs_unused, buffs_used;
while (bam_connection_is_active) { /* timer loop */
++inactive_cycles;
@@ -1162,12 +1177,47 @@
handle_bam_mux_cmd(&info->work);
}
- if (inactive_cycles == POLLING_INACTIVITY) {
+ if (inactive_cycles >= POLLING_INACTIVITY) {
rx_switch_to_interrupt_mode();
break;
}
- usleep_range(POLLING_MIN_SLEEP, POLLING_MAX_SLEEP);
+ if (bam_adaptive_timer_enabled) {
+ usleep_range(rx_timer_interval, rx_timer_interval + 50);
+
+ ret = sps_get_unused_desc_num(bam_rx_pipe,
+ &buffs_unused);
+
+ if (ret) {
+ pr_err("%s: error getting num buffers unused after sleep\n",
+ __func__);
+
+ break;
+ }
+
+ buffs_used = NUM_BUFFERS - buffs_unused;
+
+ if (buffs_unused == 0) {
+ rx_timer_interval = MIN_POLLING_SLEEP;
+ } else {
+ if (buffs_used > 0) {
+ rx_timer_interval =
+ (2 * NUM_BUFFERS *
+ rx_timer_interval)/
+ (3 * buffs_used);
+ } else {
+ rx_timer_interval =
+ MAX_POLLING_SLEEP;
+ }
+ }
+
+ if (rx_timer_interval > MAX_POLLING_SLEEP)
+ rx_timer_interval = MAX_POLLING_SLEEP;
+ else if (rx_timer_interval < MIN_POLLING_SLEEP)
+ rx_timer_interval = MIN_POLLING_SLEEP;
+ } else {
+ usleep_range(POLLING_MIN_SLEEP, POLLING_MAX_SLEEP);
+ }
}
}
@@ -2379,6 +2429,8 @@
bam_dmux_state_logging_disabled = 1;
}
+ rx_timer_interval = DEFAULT_POLLING_MIN_SLEEP;
+
subsys_notif_register_notifier("modem", &restart_notifier);
return platform_driver_register(&bam_dmux_driver);
}