[PATCH 2/2] usb: musb: Size 1 dma in transfers won't complete with cpp41

[Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

At least with the cppi41 dma, size 1 in dma transfers will just wait
until the device is disconnected. This causes timeouts in cppi41 dma
runtime PM.

Also the initial size 8 transfers take about 200ms to complete when
plugging a USB mass storage device to a hub. But we probably want to
keep those to avoid using PIO.

Fix the issue by adding a quirk for cppi41 and skip size 1 in dma if
set.

Note that additional cpp41 patches are needed to avoid error -115
messages, but that can be applied separately.

Fixes: fdea2d09b997 ("dmaengine: cppi41: Add basic PM runtime support")
Signed-off-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
---
 drivers/usb/musb/musb_cppi41.c |  1 +
 drivers/usb/musb/musb_dma.h    |  3 +++
 drivers/usb/musb/musb_host.c   | 16 +++++++++++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c
--- a/drivers/usb/musb/musb_cppi41.c
+++ b/drivers/usb/musb/musb_cppi41.c
@@ -695,6 +695,7 @@ cppi41_dma_controller_create(struct musb *musb, void __iomem *base)
 	controller->controller.channel_program = cppi41_dma_channel_program;
 	controller->controller.channel_abort = cppi41_dma_channel_abort;
 	controller->controller.is_compatible = cppi41_is_compatible;
+	controller->controller.quirks = MUSB_DMA_QUIRK_CPPI41_IN;
 
 	ret = cppi41_dma_controller_start(controller);
 	if (ret)
diff --git a/drivers/usb/musb/musb_dma.h b/drivers/usb/musb/musb_dma.h
--- a/drivers/usb/musb/musb_dma.h
+++ b/drivers/usb/musb/musb_dma.h
@@ -171,6 +171,8 @@ dma_channel_status(struct dma_channel *c)
 	return (is_dma_capable() && c) ? c->status : MUSB_DMA_STATUS_UNKNOWN;
 }
 
+#define MUSB_DMA_QUIRK_CPPI41_IN	BIT(0)
+
 /**
  * struct dma_controller - A DMA Controller.
  * @start: call this to start a DMA controller;
@@ -196,6 +198,7 @@ struct dma_controller {
 	int			(*is_compatible)(struct dma_channel *channel,
 							u16 maxpacket,
 							void *buf, u32 length);
+	unsigned int quirks;
 };
 
 /* called after channel_program(), may indicate a fault */
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -743,6 +743,8 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
 
 	musb_ep_select(mbase, epnum);
 
+	dma_controller = musb->dma_controller;
+
 	if (is_out && !len) {
 		use_dma = 0;
 		csr = musb_readw(epio, MUSB_TXCSR);
@@ -751,8 +753,20 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
 		hw_ep->tx_channel = NULL;
 	}
 
+	/*
+	 * At least cppi41 in dma will just hang with size of 1 until the
+	 * device is disconnected.
+	 */
+	if (!is_out && dma_controller &&
+	    (dma_controller->quirks & MUSB_DMA_QUIRK_CPPI41_IN)) {
+		use_dma = 0;
+		csr = musb_readw(epio, MUSB_RXCSR);
+		csr &= ~MUSB_RXCSR_DMAENAB;
+		musb_writew(epio, MUSB_RXCSR, csr);
+		hw_ep->rx_channel = NULL;
+	}
+
 	/* candidate for DMA? */
-	dma_controller = musb->dma_controller;
 	if (use_dma && is_dma_capable() && epnum && dma_controller) {
 		dma_channel = is_out ? hw_ep->tx_channel : hw_ep->rx_channel;
 		if (!dma_channel) {
-- 
2.11.0
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html