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 <[email protected]> Signed-off-by: Daniel Mack <[email protected]> --- 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); } } -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
