Patch "usb: musb: dsps: implement clear_ep_rxintr() callback" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

usb: musb: dsps: implement clear_ep_rxintr() callback

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-musb-dsps-implement-clear_ep_rxintr-callback.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bin Liu <[email protected]>
Date: Tue, 3 Jan 2017 18:13:47 -0600
Subject: usb: musb: dsps: implement clear_ep_rxintr() callback

From: Bin Liu <[email protected]>

commit c48400baa02155a5ddad63e8554602e48782278c upstream.

During dma teardown for dequque urb, if musb load is high, musb might generate bogus rx ep interrupt even when the rx fifo is flushed. In such case any of the follow log messages could happen.

    musb_host_rx 1853: BOGUS RX2 ready, csr 0000, count 0

    musb_host_rx 1936: RX3 dma busy, csr 2020

As mentioned in the current inline comment, clearing ep interrupt in the teardown path avoids the bogus interrupt, so implement clear_ep_rxintr() callback.

This bug seems to be existing since the initial driver for musb support, but I only validated the fix back to v4.1, so only cc stable for v4.1+.

---
 drivers/usb/musb/musb_dsps.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

@@ -301,6 +301,17 @@ static void otg_timer(unsigned long _mus
 	spin_unlock_irqrestore(&musb->lock, flags);
 }
 
+void dsps_musb_clear_ep_rxintr(struct musb *musb, int epnum)
+{
+	u32 epintr;
+	struct dsps_glue *glue = dev_get_drvdata(musb->controller->parent);
+	const struct dsps_musb_wrapper *wrp = glue->wrp;
+
+	/* musb->lock might already been held */
+	epintr = (1 << epnum) << wrp->rxep_shift;
+	musb_writel(musb->ctrl_base, wrp->epintr_status, epintr);
+}
+
 static irqreturn_t dsps_interrupt(int irq, void *hci)
 {
 	struct musb  *musb = hci;

@@ -647,6 +658,7 @@ static struct musb_platform_ops dsps_ops
 	.try_idle	= dsps_musb_try_idle,
 	.set_mode	= dsps_musb_set_mode,
 	.recover	= dsps_musb_recover,
+	.clear_ep_rxintr = dsps_musb_clear_ep_rxintr,
 };
 
 static u64 musb_dmamask = DMA_BIT_MASK(32);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/usb-musb-dsps-implement-clear_ep_rxintr-callback.patch queue-4.4/usb-musb-core-add-clear_ep_rxintr-to-musb_platform_ops.patch