linux-kernel - [PATCH 3.12 105/123] usb: musb: cppi41: improve rx channel abort routine

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Date:	Wed, 28 Oct 2015 14:53:36 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Bin Liu <b-liu@...com>,
	Felipe Balbi <balbi@...com>, Oliver Neukum <ONeukum@...e.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 105/123] usb: musb: cppi41: improve rx channel abort routine

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

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

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>
Cc: Oliver Neukum <ONeukum@...e.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/usb/musb/musb_cppi41.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c
index 77b475a43dad..1c9c626248fd 100644
--- a/drivers/usb/musb/musb_cppi41.c
+++ b/drivers/usb/musb/musb_cppi41.c
@@ -507,10 +507,15 @@ static int cppi41_dma_channel_abort(struct dma_channel *channel)
 		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;
@@ -524,13 +529,14 @@ static int cppi41_dma_channel_abort(struct dma_channel *channel)
 		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;
-- 
2.6.2

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