linux-kernel - [PATCH 08/11] bus: mhi: MHI CB support for Channel error notification

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Message-Id: <20251211-siva_mhi_dp2-v1-8-d2895c4ec73a@oss.qualcomm.com>
Date: Thu, 11 Dec 2025 13:37:40 +0530
From: Sivareddy Surasani <sivareddy.surasani@....qualcomm.com>
To: Manivannan Sadhasivam <mani@...nel.org>, Jonathan Corbet <corbet@....net>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Upal Kumar Saha <upal.saha@....qualcomm.com>,
        Himanshu Shukla <quic_himashuk@...cinc.com>,
        Sivareddy Surasani <sivareddy.surasani@....qualcomm.com>,
        Vivek Pernamitta <vivek.pernamitta@....qualcomm.com>
Subject: [PATCH 08/11] bus: mhi: MHI CB support for Channel error
 notification

From: Vivek Pernamitta <vivek.pernamitta@....qualcomm.com>

If a device reports an error on any channel, it sends a
CH_ERROR_EVENT over the control event ring. Update the host to
parse the entire channel list, check the channel context ring
for CH_STATE_ERROR, and notify the client. This enables the
client driver to take appropriate action as needed.

Signed-off-by: Vivek Pernamitta <vivek.pernamitta@....qualcomm.com>
Signed-off-by: Sivareddy Surasani <sivareddy.surasani@....qualcomm.com>
---
 drivers/bus/mhi/common.h    |  1 +
 drivers/bus/mhi/host/main.c | 24 ++++++++++++++++++++++++
 include/linux/mhi.h         |  2 ++
 3 files changed, 27 insertions(+)

diff --git a/drivers/bus/mhi/common.h b/drivers/bus/mhi/common.h
index 31ff4d2e6eba..3b3ecbc6169f 100644
--- a/drivers/bus/mhi/common.h
+++ b/drivers/bus/mhi/common.h
@@ -230,6 +230,7 @@ enum mhi_pkt_type {
 	MHI_PKT_TYPE_TX_EVENT = 0x22,
 	MHI_PKT_TYPE_RSC_TX_EVENT = 0x28,
 	MHI_PKT_TYPE_EE_EVENT = 0x40,
+	MHI_PKT_TYPE_CH_ERROR_EVENT = 0x41,
 	MHI_PKT_TYPE_TSYNC_EVENT = 0x48,
 	MHI_PKT_TYPE_BW_REQ_EVENT = 0x50,
 	MHI_PKT_TYPE_STALE_EVENT, /* internal event */
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 53bb93da4017..9772fb13400c 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -798,6 +798,27 @@ static int parse_rsc_event(struct mhi_controller *mhi_cntrl,
 	return 0;
 }
 
+static void mhi_process_channel_error(struct mhi_controller *mhi_cntrl)
+{
+	struct mhi_chan *mhi_chan;
+	struct mhi_chan_ctxt *chan_ctxt;
+	struct mhi_device *mhi_dev;
+	int i;
+
+	mhi_chan = mhi_cntrl->mhi_chan;
+	for (i = 0; i < mhi_cntrl->max_chan; i++, mhi_chan++) {
+		chan_ctxt = &mhi_cntrl->mhi_ctxt->chan_ctxt[mhi_chan->chan];
+
+		if ((chan_ctxt->chcfg & CHAN_CTX_CHSTATE_MASK) == MHI_CH_STATE_ERROR) {
+			dev_err(&mhi_cntrl->mhi_dev->dev,
+				"ch_id:%d is moved to error state by device", mhi_chan->chan);
+				mhi_dev = mhi_chan->mhi_dev;
+			if (mhi_dev)
+				mhi_notify(mhi_dev, MHI_CB_CHANNEL_ERROR);
+		}
+	}
+}
+
 static void mhi_process_cmd_completion(struct mhi_controller *mhi_cntrl,
 				       struct mhi_ring_element *tre)
 {
@@ -961,6 +982,9 @@ int mhi_process_ctrl_ev_ring(struct mhi_controller *mhi_cntrl,
 
 			break;
 		}
+		case MHI_PKT_TYPE_CH_ERROR_EVENT:
+			mhi_process_channel_error(mhi_cntrl);
+			break;
 		case MHI_PKT_TYPE_TX_EVENT:
 			chan = MHI_TRE_GET_EV_CHID(local_rp);
 
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 926a20835467..66fd83bed306 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -34,6 +34,7 @@ struct mhi_buf_info;
  * @MHI_CB_SYS_ERROR: MHI device entered error state (may recover)
  * @MHI_CB_FATAL_ERROR: MHI device entered fatal error state
  * @MHI_CB_BW_REQ: Received a bandwidth switch request from device
+ * @MHI_CB_CHANNEL_ERROR: MHI channel entered error state from device
  */
 enum mhi_callback {
 	MHI_CB_IDLE,
@@ -45,6 +46,7 @@ enum mhi_callback {
 	MHI_CB_SYS_ERROR,
 	MHI_CB_FATAL_ERROR,
 	MHI_CB_BW_REQ,
+	MHI_CB_CHANNEL_ERROR,
 };
 
 /**

-- 
2.34.1