linux-kernel - [PATCH 3.16 159/192] usb: musb: cppi41: improve rx channel abort routine

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Date:   Mon, 09 Oct 2017 13:44:25 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Bin Liu" <b-liu@...com>,
        "Felipe Balbi" <balbi@...com>
Subject: [PATCH 3.16 159/192] usb: musb: cppi41: improve rx channel abort
 routine

3.16.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Bin Liu <b-liu@...com>

commit cb83df77f3ec151d68a1b6be957207e6fc7b7f50 upstream.

1. set AUTOREQ to NONE at the beginning of teardown;

2. add delay for dma pipeline to drain;

3. Do not set USB_TDOWN bit for RX teardown.

  The CPPI hw has an issue that when tearing down a RX channel, if
  another RX channel is receiving data, the CPPI will lockup.

  To workaround the issue, do not set the CPPI TD bit. The steps before
  this point ensures the CPPI channel will be torn down properly.

Signed-off-by: Bin Liu <b-liu@...com>
Signed-off-by: Felipe Balbi <balbi@...com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/musb/musb_cppi41.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/usb/musb/musb_cppi41.c
+++ b/drivers/usb/musb/musb_cppi41.c
@@ -570,10 +570,15 @@ static int cppi41_dma_channel_abort(stru
 		csr &= ~MUSB_TXCSR_DMAENAB;
 		musb_writew(epio, MUSB_TXCSR, csr);
 	} else {
+		cppi41_set_autoreq_mode(cppi41_channel, EP_MODE_AUTOREQ_NONE);
+
 		csr = musb_readw(epio, MUSB_RXCSR);
 		csr &= ~(MUSB_RXCSR_H_REQPKT | MUSB_RXCSR_DMAENAB);
 		musb_writew(epio, MUSB_RXCSR, csr);
 
+		/* wait to drain cppi dma pipe line */
+		udelay(50);
+
 		csr = musb_readw(epio, MUSB_RXCSR);
 		if (csr & MUSB_RXCSR_RXPKTRDY) {
 			csr |= MUSB_RXCSR_FLUSHFIFO;
@@ -587,13 +592,14 @@ static int cppi41_dma_channel_abort(stru
 		tdbit <<= 16;
 
 	do {
-		musb_writel(musb->ctrl_base, USB_TDOWN, tdbit);
+		if (is_tx)
+			musb_writel(musb->ctrl_base, USB_TDOWN, tdbit);
 		ret = dmaengine_terminate_all(cppi41_channel->dc);
 	} while (ret == -EAGAIN);
 
-	musb_writel(musb->ctrl_base, USB_TDOWN, tdbit);
-
 	if (is_tx) {
+		musb_writel(musb->ctrl_base, USB_TDOWN, tdbit);
+
 		csr = musb_readw(epio, MUSB_TXCSR);
 		if (csr & MUSB_TXCSR_TXPKTRDY) {
 			csr |= MUSB_TXCSR_FLUSHFIFO;