patch "usb: cdns3: Fix uvc fail when DMA cross 4k boundery since sg enabled" added to usb-next

patch "usb: cdns3: Fix uvc fail when DMA cross 4k boundery since sg enabled" added to usb-next

[gregkh]

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

    usb: cdns3: Fix uvc fail when DMA cross 4k boundery since sg enabled

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


From 40c304109e866a7dc123661a5c8ca72f6b5e14e0 Mon Sep 17 00:00:00 2001
From: Frank Li <Frank.Li@nxp.com>
Date: Sun, 24 Dec 2023 10:38:15 -0500
Subject: usb: cdns3: Fix uvc fail when DMA cross 4k boundery since sg enabled

Supposed DMA cross 4k bounder problem should be fixed at DEV_VER_V2, but
still met problem when do ISO transfer if sg enabled.

Data pattern likes below when sg enabled, package size is 1k and mult is 2
	[UVC Header(8B) ] [data(3k - 8)] ...

The received data at offset 0xd000 will get 0xc000 data, len 0x70. Error
happen position as below pattern:
	0xd000: wrong
	0xe000: wrong
	0xf000: correct
	0x10000: wrong
	0x11000: wrong
	0x12000: correct
	...

To avoid DMA cross 4k bounder at ISO transfer, reduce burst len according
to start DMA address's alignment.

Cc:  <stable@vger.kernel.org>
Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20231224153816.1664687-4-Frank.Li@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/cdns3/cdns3-gadget.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 4c6893af22dd..aeca902ab6cc 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -1120,6 +1120,7 @@ static int cdns3_ep_run_transfer(struct cdns3_endpoint *priv_ep,
 	u32 togle_pcs = 1;
 	int sg_iter = 0;
 	int num_trb_req;
+	int trb_burst;
 	int num_trb;
 	int address;
 	u32 control;
@@ -1243,7 +1244,36 @@ static int cdns3_ep_run_transfer(struct cdns3_endpoint *priv_ep,
 			total_tdl += DIV_ROUND_UP(length,
 					       priv_ep->endpoint.maxpacket);
 
-		trb->length |= cpu_to_le32(TRB_BURST_LEN(priv_ep->trb_burst_size) |
+		trb_burst = priv_ep->trb_burst_size;
+
+		/*
+		 * Supposed DMA cross 4k bounder problem should be fixed at DEV_VER_V2, but still
+		 * met problem when do ISO transfer if sg enabled.
+		 *
+		 * Data pattern likes below when sg enabled, package size is 1k and mult is 2
+		 *       [UVC Header(8B) ] [data(3k - 8)] ...
+		 *
+		 * The received data at offset 0xd000 will get 0xc000 data, len 0x70. Error happen
+		 * as below pattern:
+		 *	0xd000: wrong
+		 *	0xe000: wrong
+		 *	0xf000: correct
+		 *	0x10000: wrong
+		 *	0x11000: wrong
+		 *	0x12000: correct
+		 *	...
+		 *
+		 * But it is still unclear about why error have not happen below 0xd000, it should
+		 * cross 4k bounder. But anyway, the below code can fix this problem.
+		 *
+		 * To avoid DMA cross 4k bounder at ISO transfer, reduce burst len according to 16.
+		 */
+		if (priv_ep->type == USB_ENDPOINT_XFER_ISOC && priv_dev->dev_ver <= DEV_VER_V2)
+			if (ALIGN_DOWN(trb->buffer, SZ_4K) !=
+			    ALIGN_DOWN(trb->buffer + length, SZ_4K))
+				trb_burst = 16;
+
+		trb->length |= cpu_to_le32(TRB_BURST_LEN(trb_burst) |
 					TRB_LEN(length));
 		pcs = priv_ep->pcs ? TRB_CYCLE : 0;
 
-- 
2.43.0