From 29c7f3e68eec4ae94d85ad7b5dfdafdb8089f513 Mon Sep 17 00:00:00 2001
From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
Date: Mon, 2 Oct 2017 14:01:41 +0900
Subject: [PATCH] usb: renesas_usbhs: Fix DMAC sequence for receiving
 zero-length packet
Git-commit: 29c7f3e68eec4ae94d85ad7b5dfdafdb8089f513
Patch-mainline: v4.14-rc5
References: bsc#1085536

The DREQE bit of the DnFIFOSEL should be set to 1 after the DE bit of
USB-DMAC on R-Car SoCs is set to 1 after the USB-DMAC received a
zero-length packet. Otherwise, a transfer completion interruption
of USB-DMAC doesn't happen. Even if the driver changes the sequence,
normal operations (transmit/receive without zero-length packet) will
not cause any side-effects. So, this patch fixes the sequence anyway.

Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
[shimoda: revise the commit log]
Fixes: e73a9891b3a1 ("usb: renesas_usbhs: add DMAEngine support")
Cc: <stable@vger.kernel.org> # v3.1+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/renesas_usbhs/fifo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c
index 68f26904c316..50285b01da92 100644
--- a/drivers/usb/renesas_usbhs/fifo.c
+++ b/drivers/usb/renesas_usbhs/fifo.c
@@ -857,9 +857,9 @@ static void xfer_work(struct work_struct *work)
 		fifo->name, usbhs_pipe_number(pipe), pkt->length, pkt->zero);
 
 	usbhs_pipe_running(pipe, 1);
-	usbhsf_dma_start(pipe, fifo);
 	usbhs_pipe_set_trans_count_if_bulk(pipe, pkt->trans);
 	dma_async_issue_pending(chan);
+	usbhsf_dma_start(pipe, fifo);
 	usbhs_pipe_enable(pipe);
 
 xfer_work_end:
-- 
2.13.6