linux-kernel - [PATCH v2 1/2] bus: mhi: host: Remove duplicate ee check for syserr

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Date:   Mon, 10 Apr 2023 09:58:11 -0600
From:   Jeffrey Hugo <quic_jhugo@...cinc.com>
To:     <mani@...nel.org>
CC:     <mhi@...ts.linux.dev>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Jeffrey Hugo <quic_jhugo@...cinc.com>, <stable@...r.kernel.org>
Subject: [PATCH v2 1/2] bus: mhi: host: Remove duplicate ee check for syserr

If we detect a system error via intvec, we only process the syserr if the
current ee is different than the last observed ee.  The reason for this
check is to prevent bhie from running multiple times, but with the single
queue handling syserr, that is not possible.

The check can cause an issue with device recovery.  If PBL loads a bad SBL
via BHI, but that SBL hangs before notifying the host of an ee change,
then issuing soc_reset to crash the device and retry (after supplying a
fixed SBL) will not recover the device as the host will observe a PBL->PBL
transition and not process the syserr.  The device will be stuck until
either the driver is reloaded, or the host is rebooted.  Instead, remove
the check so that we can attempt to recover the device.

Fixes: ef2126c4e2ea ("bus: mhi: core: Process execution environment changes serially")
Cc: stable@...r.kernel.org
Signed-off-by: Jeffrey Hugo <quic_jhugo@...cinc.com>
Reviewed-by: Carl Vanderlip <quic_carlv@...cinc.com>
Reviewed-by: Manivannan Sadhasivam <mani@...nel.org>
---
 drivers/bus/mhi/host/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 4fa0969..3a08518 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -503,7 +503,7 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
 	}
 	write_unlock_irq(&mhi_cntrl->pm_lock);

-	if (pm_state != MHI_PM_SYS_ERR_DETECT || ee == mhi_cntrl->ee)
+	if (pm_state != MHI_PM_SYS_ERR_DETECT)
 		goto exit_intvec;

 	switch (ee) {
-- 
2.7.4