Commit 0090114d authored Mar 10, 2017 by Bin Liu Committed by Greg Kroah-Hartman Mar 14, 2017

usb: musb: cppi41: don't check early-TX-interrupt for Isoch transfer



The CPPI 4.1 driver polls register to workaround the premature TX
interrupt issue, but it causes audio playback underrun when triggered in
Isoch transfers.

Isoch doesn't do back-to-back transfers, the TX should be done by the
time the next transfer is scheduled. So skip this polling workaround for
Isoch transfer.

Fixes: a655f481 ("usb: musb: musb_cppi41: handle pre-mature TX complete interrupt")
Cc: <stable@vger.kernel.org> #4.1+
Reported-by: Alexandre Bailon <abailon@baylibre.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Alexandre Bailon <abailon@baylibre.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3243367b

drivers/usb/musb/musb_cppi41.c

+21 −2

Original line number	Diff line number	Diff line
		@@ -238,8 +238,27 @@ static void cppi41_dma_callback(void *private_data,
		transferred < cppi41_channel->packet_sz)
		cppi41_channel->prog_len = 0;

		if (cppi41_channel->is_tx)
		if (cppi41_channel->is_tx) {
		u8 type;

		if (is_host_active(musb))
		type = hw_ep->out_qh->type;
		else
		type = hw_ep->ep_in.type;

		if (type == USB_ENDPOINT_XFER_ISOC)
		/*
		* Don't use the early-TX-interrupt workaround below
		* for Isoch transfter. Since Isoch are periodic
		* transfer, by the time the next transfer is
		* scheduled, the current one should be done already.
		*
		* This avoids audio playback underrun issue.
		*/
		empty = true;
		else
		empty = musb_is_tx_fifo_empty(hw_ep);
		}

		if (!cppi41_channel->is_tx \|\| empty) {
		cppi41_trans_done(cppi41_channel);