From a5e4aa4d770ae96da52c8fa035751d2046e2434f Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Wed, 3 Sep 2014 17:21:24 +0200 Subject: [PATCH] usb: musb: cppi41: tweak hrtimer values Intensive tests with USB audio devices connected to a musb host port have shown reproducible pops and clicks in both the playback and the capture stream. These are related to how the early_tx hrtimer is set up, and it turns out they can be fixed by reducing the timer's slack value from 40 to 25 us. Also, when the callback is ran without taking action, it should be rescheduled 20 us later instead of 50 us. Reported-and-tested-by: Sven Neumann Signed-off-by: Daniel Mack Signed-off-by: Felipe Balbi --- drivers/usb/musb/musb_cppi41.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c index 47ae645..ecdd632 100644 --- a/drivers/usb/musb/musb_cppi41.c +++ b/drivers/usb/musb/musb_cppi41.c @@ -200,7 +200,7 @@ static enum hrtimer_restart cppi41_recheck_tx_req(struct hrtimer *timer) if (!list_empty(&controller->early_tx_list)) { ret = HRTIMER_RESTART; hrtimer_forward_now(&controller->early_tx, - ktime_set(0, 50 * NSEC_PER_USEC)); + ktime_set(0, 20 * NSEC_PER_USEC)); } spin_unlock_irqrestore(&musb->lock, flags); @@ -278,7 +278,7 @@ static void cppi41_dma_callback(void *private_data) hrtimer_start_range_ns(&controller->early_tx, ktime_set(0, usecs * NSEC_PER_USEC), - 40 * NSEC_PER_USEC, + 20 * NSEC_PER_USEC, HRTIMER_MODE_REL); } } -- 2.7.4