[v3,13/15] usb: dwc3: Add workaround for isoc start transfer failure

[v3,13/15] usb: dwc3: Add workaround for isoc start transfer failure

[Thinh Nguyen]

In DWC_usb31 version 1.70a-ea06 and prior, for highspeed and fullspeed
isochronous IN, BIT[15:14] of the 16-bit microframe number reported by
the XferNotReady event are invalid. The driver uses this number to
schedule the isochronous transfer and passes it to the START TRANSFER
command. Because this number is invalid, the command may fail. If
BIT[15:14] matches the internal 16-bit microframe, the START TRANSFER
command will pass and the transfer will start at the scheduled time, if
it is off by 1, the command will still pass, but the transfer will start
2 seconds in the future. All other conditions the START TRANSFER command
will fail with bus-expiry.

In order to workaround this issue, we can issue multiple START TRANSFER
commands with different values of BIT[15:14]: 'b00, 'b01, 'b10, and 'b11
and do an END TRANSFER command. Each combination is 2 seconds apart. 4
seconds into the future will cause a bus-expiry failure. As the result,
within the 4 possible combinations for BIT[15:14], there will be 2
successful and 2 failure START COMMAND status. One of the 2 successful
command status will result in a 2-second delay. The smaller BIT[15:14]
value is the correct one.

Since there are only 4 outcomes and the results are ordered, we can
simply test 2 START TRANSFER commands with BIT[15:14] combinations 'b00
and 'b01 to deduce the smallest successful combination.

            +---------+---------+
            | BIT(15) | BIT(14) |
            +=========+=========+
     test0  |   0     |    0    |
            +---------+---------+
     test1  |   0     |    1    |
            +---------+---------+

With test0 and test1 BIT[15:14] combinations, here is the logic:
if test0 passes and test1 passes, BIT[15:14] is 'b00
if test0 passes and test1 fails, BIT[15:14] is 'b11
if test0 fails and test1 fails, BIT[15:14] is 'b10
if test0 fails and test1 passes, BIT[15:14] is 'b01

Synopsys STAR 9001202023: Wrong microframe number for isochronous IN
endpoints.

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
---
 drivers/usb/dwc3/core.c   |   2 +
 drivers/usb/dwc3/core.h   |  13 ++++
 drivers/usb/dwc3/gadget.c | 189 ++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 199 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index ecf3f6f51fda..a42410e18b2f 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1073,6 +1073,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				"snps,is-utmi-l1-suspend");
 	device_property_read_u8(dev, "snps,hird-threshold",
 				&hird_threshold);
+	dwc->dis_start_transfer_quirk = device_property_read_bool(dev,
+				"snps,dis-start-transfer-quirk");
 	dwc->usb3_lpm_capable = device_property_read_bool(dev,
 				"snps,usb3_lpm_capable");
 	device_property_read_u8(dev, "snps,rx-thr-num-pkt-prd",
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 71cf53a06e49..c09cd0c6354e 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -555,6 +555,10 @@ struct dwc3_event_buffer {
  * @name: a human readable name e.g. ep1out-bulk
  * @direction: true for TX, false for RX
  * @stream_capable: true when streams are enabled
+ * @frame_number_15_14: BIT[15:14] of the frame number to test isochronous
+ *		START TRANSFER command failure workaround
+ * @test0_status: the result of testing START TRANSFER command with
+ *		frame_number_15_14 = 'b00 (non-zero means failure)
  */
 struct dwc3_ep {
 	struct usb_ep		endpoint;
@@ -608,6 +612,10 @@ struct dwc3_ep {
 
 	unsigned		direction:1;
 	unsigned		stream_capable:1;
+
+	/* Isochronous START TRANSFER workaround for STAR 9001202023 */
+	u8			frame_number_15_14;
+	int			test0_status;
 };
 
 enum dwc3_phy {
@@ -862,6 +870,8 @@ struct dwc3_scratchpad_array {
  * @pullups_connected: true when Run/Stop bit is set
  * @setup_packet_pending: true when there's a Setup Packet in FIFO. Workaround
  * @three_stage_setup: set if we perform a three phase setup
+ * @dis_start_transfer_quirk: set if start_transfer failure SW workaround is
+ *			not needed for DWC_usb31 version 1.70a-ea06 and below
  * @usb3_lpm_capable: set if hadrware supports Link Power Management
  * @disable_scramble_quirk: set if we enable the disable scramble quirk
  * @u2exit_lfps_quirk: set if we enable u2exit lfps quirk
@@ -982,10 +992,12 @@ struct dwc3 {
 #define DWC3_REVISION_IS_DWC31		0x80000000
 #define DWC3_USB31_REVISION_110A	(0x3131302a | DWC3_REVISION_IS_DWC31)
 #define DWC3_USB31_REVISION_120A	(0x3132302a | DWC3_REVISION_IS_DWC31)
+#define DWC3_USB31_REVISION_170A	(0x3137302a | DWC3_REVISION_IS_DWC31)
 
 	u32			ver_type;
 
 #define DWC31_VERSIONTYPE_EA01		0x65613031
+#define DWC31_VERSIONTYPE_EA06		0x65613036
 
 	enum dwc3_ep0_next	ep0_next_event;
 	enum dwc3_ep0_state	ep0state;
@@ -1029,6 +1041,7 @@ struct dwc3 {
 	unsigned		pullups_connected:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;
+	unsigned		dis_start_transfer_quirk:1;
 	unsigned		usb3_lpm_capable:1;
 
 	unsigned		disable_scramble_quirk:1;
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 24cbd79481e8..f873ebb40ea8 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1241,6 +1241,161 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep)
 	return 0;
 }
 
+static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
+				    struct dwc3_request *req,
+				    struct dwc3_trb *trb,
+				    const struct dwc3_event_depevt *event,
+				    int status, int chain);
+
+/**
+ * set_isoc_start_frame - set valid wrap-around isoc start frame bits
+ * @dwc: pointer to our context structure
+ * @dep: isoc endpoint
+ * @cur_uf: The current microframe taken from XferNotReady event
+ *
+ * This function tests for the correct combination of BIT[15:14] from
+ * the 16-bit microframe number reported by the XferNotReady event and
+ * set it to dep->frame_number.
+ *
+ * In DWC_usb31 version 1.70a-ea06 and prior, for highspeed and fullspeed
+ * isochronous IN, BIT[15:14] of the 16-bit microframe number reported by
+ * the XferNotReady event are invalid. The driver uses this number to
+ * schedule the isochronous transfer and passes it to the START TRANSFER
+ * command. Because this number is invalid, the command may fail. If
+ * BIT[15:14] matches the internal 16-bit microframe, the START TRANSFER
+ * command will pass and the transfer will start at the scheduled time, if
+ * it is off by 1, the command will still pass, but the transfer will start
+ * 2 seconds in the future. All other conditions the START TRANSFER command
+ * will fail with bus-expiry.
+ *
+ * In order to workaround this issue, we can issue multiple START TRANSFER
+ * commands with different values of BIT[15:14]: 'b00, 'b01, 'b10, and 'b11
+ * and do an END TRANSFER command. Each combination is 2 seconds apart. 4
+ * seconds into the future will cause a bus-expiry failure. As the result,
+ * within the 4 possible combinations for BIT[15:14], there will be 2
+ * successful and 2 failure START COMMAND status. One of the 2 successful
+ * command status will result in a 2-second delay. The smaller BIT[15:14]
+ * value is the correct one.
+ *
+ * Since there are only 4 outcomes and the results are ordered, we can
+ * simply test 2 START TRANSFER commands with BIT[15:14] combinations 'b00
+ * and 'b01 to deduce the smallest successful combination.
+ *
+ *             +---------+---------+
+ *             | BIT(15) | BIT(14) |
+ *             +=========+=========+
+ *      test0  |   0     |    0    |
+ *             +---------+---------+
+ *      test1  |   0     |    1    |
+ *             +---------+---------+
+ *
+ * With test0 and test1 BIT[15:14] combinations, here is the logic:
+ * if test0 passes and test1 passes, BIT[15:14] is 'b00
+ * if test0 passes and test1 fails, BIT[15:14] is 'b11
+ * if test0 fails and test1 fails, BIT[15:14] is 'b10
+ * if test0 fails and test1 passes, BIT[15:14] is 'b01
+ *
+ * Synopsys STAR 9001202023: Wrong microframe number for isochronous IN
+ * endpoints.
+ *
+ * Return 0 if the dep->frame_number is set, return 1 if END TRANSFER
+ * command is executed, and return negative errno.
+ */
+static int set_isoc_start_frame(struct dwc3 *dwc, struct dwc3_ep *dep,
+				u32 cur_uf)
+{
+	struct dwc3_request *req;
+	int ret = 0;
+	int test0, test1;
+
+	/* Store the 14-bit frame number on the first test */
+	if (!dep->frame_number_15_14)
+		dep->frame_number = cur_uf & ~(BIT(14) | BIT(15));
+
+	while (dep->frame_number_15_14 < 2) {
+		u32 cmd;
+		u32 frame_number;
+		struct dwc3_gadget_ep_cmd_params params;
+		struct dwc3_event_depevt event;
+
+		event.endpoint_number = dep->number;
+		event.endpoint_event = DWC3_DEPEVT_EPCMDCMPLT;
+
+		req = next_request(&dep->pending_list);
+		if (!req) {
+			dev_info(dwc->dev, "%s: ran out of requests\n",
+				 dep->name);
+			dep->flags |= DWC3_EP_PENDING_REQUEST;
+			return -EINVAL;
+		}
+
+		frame_number = dep->frame_number;
+		frame_number |= dep->frame_number_15_14 << 14;
+		frame_number += max_t(u32, 16, dep->interval);
+
+		dwc3_prepare_one_trb(dep, req, false, 0);
+
+		params.param0 = upper_32_bits(req->trb_dma);
+		params.param1 = lower_32_bits(req->trb_dma);
+
+		cmd = DWC3_DEPCMD_STARTTRANSFER;
+		cmd |= DWC3_DEPCMD_PARAM(frame_number);
+		ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
+
+		if (dep->frame_number_15_14 == 0)
+			dep->test0_status = ret;
+
+		if (!ret) {
+			dep->resource_index =
+				dwc3_gadget_ep_get_transfer_index(dep);
+			dwc3_stop_active_transfer(dep->dwc, dep->number, true);
+		}
+
+		__dwc3_cleanup_done_trbs(dep->dwc, dep, req, req->trb,
+					 &event, 0, false);
+		req->trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
+		dwc3_gadget_giveback(dep, req, 0);
+
+		dep->frame_number_15_14++;
+
+		/*
+		 * Return early and wait for the next XferNotReady event to come
+		 * before sending the next START TRANSFER command.
+		 */
+		if (!ret)
+			return 1;
+
+		/* End test if not bus-expiry status */
+		if (ret != -EAGAIN) {
+			dep->test0_status = -EINVAL;
+			dep->frame_number_15_14 = 0;
+			return ret;
+		}
+	}
+
+	/* test0 and test1 are both completed at this point */
+	test0 = (dep->test0_status == 0);
+	test1 = (ret == 0);
+
+	if (!test0 && test1)
+		dep->frame_number_15_14 = 1;
+	else if (!test0 && !test1)
+		dep->frame_number_15_14 = 2;
+	else if (test0 && !test1)
+		dep->frame_number_15_14 = 3;
+	else if (test0 && test1)
+		dep->frame_number_15_14 = 0;
+
+	dep->frame_number |= dep->frame_number_15_14 << 14;
+	dep->frame_number += max_t(u32, 16, dep->interval);
+
+	/* Reinitialize test variables */
+	dep->test0_status = -EINVAL;
+	dep->frame_number_15_14 = 0;
+
+	return 0;
+}
+
 static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
 {
 	u32			reg;
@@ -1252,6 +1407,8 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
 static void __dwc3_gadget_start_isoc(struct dwc3 *dwc,
 		struct dwc3_ep *dep, u32 cur_uf)
 {
+	bool need_isoc_start_transfer_workaround = false;
+
 	if (list_empty(&dep->pending_list)) {
 		dev_info(dwc->dev, "%s: ran out of requests\n",
 				dep->name);
@@ -1259,11 +1416,31 @@ static void __dwc3_gadget_start_isoc(struct dwc3 *dwc,
 		return;
 	}
 
-	/*
-	 * Schedule the first trb for one interval in the future or at
-	 * least 4 microframes.
-	 */
-	dep->frame_number = cur_uf + max_t(u32, 4, dep->interval);
+	if (dwc3_is_usb31(dwc) && dwc->revision <= DWC3_USB31_REVISION_170A) {
+		need_isoc_start_transfer_workaround = true;
+
+		/* for 1.70a only ea01 to ea06 are affected */
+		if (dwc->revision == DWC3_USB31_REVISION_170A &&
+		    !(dwc->ver_type >= DWC31_VERSIONTYPE_EA01 &&
+		      dwc->ver_type <= DWC31_VERSIONTYPE_EA06))
+			need_isoc_start_transfer_workaround = false;
+	}
+
+	if (!dwc->dis_start_transfer_quirk &&
+	    need_isoc_start_transfer_workaround &&
+	    dep->direction &&
+	    (dwc->gadget.speed == USB_SPEED_HIGH ||
+	     dwc->gadget.speed == USB_SPEED_FULL)) {
+		if (set_isoc_start_frame(dwc, dep, cur_uf))
+			return;
+	} else {
+		/*
+		 * Schedule the first trb for one interval in the future or at
+		 * least 4 microframes.
+		 */
+		dep->frame_number = cur_uf + max_t(u32, 4, dep->interval);
+	}
+
 	__dwc3_gadget_kick_transfer(dep);
 }
 
@@ -2073,6 +2250,8 @@ static int dwc3_gadget_init_endpoints(struct dwc3 *dwc, u8 total)
 		dep->number = epnum;
 		dep->direction = direction;
 		dep->regs = dwc->regs + DWC3_DEP_BASE(epnum);
+		dep->frame_number_15_14 = 0;
+		dep->test0_status = -EINVAL;
 		dwc->eps[epnum] = dep;
 
 		snprintf(dep->name, sizeof(dep->name), "ep%u%s", num,