[PATCH v3 1/7] usb: mtu3: give back request when rx error happens

[Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>]

When the Rx enconnter errors, currently, only print error logs, that
may cause class driver's RX halt, shall give back the request with
error status meanwhile.

Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
---
v3: no changes
v2: remove @req suggested by AngeloGioacchino
---
 drivers/usb/mtu3/mtu3_qmu.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/mtu3/mtu3_qmu.c b/drivers/usb/mtu3/mtu3_qmu.c
index a2fdab8b63b2..a4da1af0b2c0 100644
--- a/drivers/usb/mtu3/mtu3_qmu.c
+++ b/drivers/usb/mtu3/mtu3_qmu.c
@@ -466,6 +466,37 @@ static void qmu_tx_zlp_error_handler(struct mtu3 *mtu, u8 epnum)
 	mtu3_qmu_resume(mep);
 }
 
+/*
+ * when rx error happens (except zlperr), QMU will stop, and RQCPR saves
+ * the GPD encountered error, Done irq will arise after resuming QMU again.
+ */
+static void qmu_error_rx(struct mtu3 *mtu, u8 epnum)
+{
+	struct mtu3_ep *mep = mtu->out_eps + epnum;
+	struct mtu3_gpd_ring *ring = &mep->gpd_ring;
+	struct qmu_gpd *gpd_current = NULL;
+	struct mtu3_request *mreq;
+	dma_addr_t cur_gpd_dma;
+
+	cur_gpd_dma = read_rxq_cur_addr(mtu->mac_base, epnum);
+	gpd_current = gpd_dma_to_virt(ring, cur_gpd_dma);
+
+	mreq = next_request(mep);
+	if (!mreq || mreq->gpd != gpd_current) {
+		dev_err(mtu->dev, "no correct RX req is found\n");
+		return;
+	}
+
+	mreq->request.status = -EAGAIN;
+
+	/* by pass the current GDP */
+	gpd_current->dw0_info |= cpu_to_le32(GPD_FLAGS_BPS | GPD_FLAGS_HWO);
+	mtu3_qmu_resume(mep);
+
+	dev_dbg(mtu->dev, "%s EP%d, current=%p, req=%p\n",
+		__func__, epnum, gpd_current, mreq);
+}
+
 /*
  * NOTE: request list maybe is already empty as following case:
  * queue_tx --> qmu_interrupt(clear interrupt pending, schedule tasklet)-->
@@ -571,14 +602,18 @@ static void qmu_exception_isr(struct mtu3 *mtu, u32 qmu_status)
 
 	if ((qmu_status & RXQ_CSERR_INT) || (qmu_status & RXQ_LENERR_INT)) {
 		errval = mtu3_readl(mbase, U3D_RQERRIR0);
+		mtu3_writel(mbase, U3D_RQERRIR0, errval);
+
 		for (i = 1; i < mtu->num_eps; i++) {
 			if (errval & QMU_RX_CS_ERR(i))
 				dev_err(mtu->dev, "Rx %d CS error!\n", i);
 
 			if (errval & QMU_RX_LEN_ERR(i))
 				dev_err(mtu->dev, "RX %d Length error\n", i);
+
+			if (errval & (QMU_RX_CS_ERR(i) | QMU_RX_LEN_ERR(i)))
+				qmu_error_rx(mtu, i);
 		}
-		mtu3_writel(mbase, U3D_RQERRIR0, errval);
 	}
 
 	if (qmu_status & RXQ_ZLPERR_INT) {
-- 
2.18.0