linux-kernel - [PATCH v3] bus: mhi: host: Skip MHI reset if device is in RDDM

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Date:   Fri, 12 May 2023 10:05:58 +0800
From:   Qiang Yu <quic_qianyu@...cinc.com>
To:     mani@...nel.org, quic_jhugo@...cinc.com
Cc:     mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_cang@...cinc.com,
        quic_mrana@...cinc.com, Qiang Yu <quic_qianyu@...cinc.com>
Subject: [PATCH v3] bus: mhi: host: Skip MHI reset if device is in RDDM

In RDDM EE, device can not process MHI reset issued by host. In case of MHI
power off, host is issuing MHI reset and polls for it to get cleared until
it times out. Since this timeout can not be avoided in case of RDDM, skip
the MHI reset in this scenarios.

Fixes: a6e2e3522f29 ("bus: mhi: core: Add support for PM state transitions")
Signed-off-by: Qiang Yu <quic_qianyu@...cinc.com>
---
v1->v2: use ~75 columns in commit text,	add Fixes tag
v2->v3: update Fixes tag
 
 drivers/bus/mhi/host/pm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
index 0834590..8a4362d 100644
--- a/drivers/bus/mhi/host/pm.c
+++ b/drivers/bus/mhi/host/pm.c
@@ -470,6 +470,10 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
 
 	/* Trigger MHI RESET so that the device will not access host memory */
 	if (!MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
+		/* Skip MHI RESET if in RDDM state */
+		if (mhi_cntrl->rddm_image && mhi_get_exec_env(mhi_cntrl) == MHI_EE_RDDM)
+			goto skip_mhi_reset;
+
 		dev_dbg(dev, "Triggering MHI Reset in device\n");
 		mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
 
@@ -495,6 +499,7 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
 		}
 	}
 
+skip_mhi_reset:
 	dev_dbg(dev,
 		 "Waiting for all pending event ring processing to complete\n");
 	mhi_event = mhi_cntrl->mhi_event;
-- 
2.7.4