From 0090114d336a9604aa2d90bc83f20f7cd121b76c Mon Sep 17 00:00:00 2001 From: Bin Liu Date: Fri, 10 Mar 2017 14:43:35 -0600 Subject: [PATCH] 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: a655f481d83d6 ("usb: musb: musb_cppi41: handle pre-mature TX complete interrupt") Cc: #4.1+ Reported-by: Alexandre Bailon Acked-by: Sebastian Andrzej Siewior Tested-by: Alexandre Bailon Signed-off-by: Bin Liu Signed-off-by: Greg Kroah-Hartman --- drivers/usb/musb/musb_cppi41.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c index 00e272bfee39..355655f8a3fb 100644 --- a/drivers/usb/musb/musb_cppi41.c +++ b/drivers/usb/musb/musb_cppi41.c @@ -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) - empty = musb_is_tx_fifo_empty(hw_ep); + 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); -- 2.20.1