linux-kernel - [PATCH v1 6/7] bus: mhi: core: Wait for MHI READY state in most scenarios

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Date:   Mon, 29 Mar 2021 18:28:23 -0700
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     manivannan.sadhasivam@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
        carl.yin@...ctel.com, naveen.kumar@...ctel.com,
        loic.poulain@...aro.org, abickett@...eaurora.org,
        Bhaumik Bhatt <bbhatt@...eaurora.org>
Subject: [PATCH v1 6/7] bus: mhi: core: Wait for MHI READY state in most scenarios

When moving from SYS_ERROR transition to a different execution
environment, MHI host relies on the BHI register read to spawn
the next image download or wait for READY -> M0 states. The
device can at times move the execution environment to mission
mode when a pass through is expected, which can result in a
stall. Initiate a wait for MHI READY and write M0 such that the
device can proceed with state change event updates for any new
execution environment being entered. This allows us to remove
conditionals in handling firmware load for PBL modes and keeps
the execution environment out of the picture as it can change at
any time.

Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
---
 drivers/bus/mhi/core/boot.c | 4 ++--
 drivers/bus/mhi/core/pm.c   | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c
index 0f0ae88..8100cf5 100644
--- a/drivers/bus/mhi/core/boot.c
+++ b/drivers/bus/mhi/core/boot.c
@@ -416,8 +416,8 @@ void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl)
 		}
 	}
 
-	/* If device is in pass through, do reset to ready state transition */
-	if (mhi_cntrl->ee == MHI_EE_PTHRU)
+	/* wait for ready on pass through or any other execution environment */
+	if (mhi_cntrl->ee != MHI_EE_EDL && mhi_cntrl->ee != MHI_EE_PBL)
 		goto fw_load_ready_state;
 
 	fw_name = (mhi_cntrl->ee == MHI_EE_EDL) ?
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index 7ac9dfe..b6920a5 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -763,8 +763,7 @@ void mhi_pm_st_worker(struct work_struct *work)
 			if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state))
 				mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
 			write_unlock_irq(&mhi_cntrl->pm_lock);
-			if (MHI_IN_PBL(mhi_cntrl->ee))
-				mhi_fw_load_handler(mhi_cntrl);
+			mhi_fw_load_handler(mhi_cntrl);
 			break;
 		case DEV_ST_TRANSITION_SBL:
 			write_lock_irq(&mhi_cntrl->pm_lock);
-- 
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