linux-kernel - [PATCH 06/29] bus: mhi: Fix channel close issue on driver remove

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Date:   Wed,  2 Dec 2020 15:11:36 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     hemantk@...eaurora.org, bbhatt@...eaurora.org,
        linux-arm-msm@...r.kernel.org, jhugo@...eaurora.org,
        linux-kernel@...r.kernel.org, loic.poulain@...aro.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH 06/29] bus: mhi: Fix channel close issue on driver remove

From: Loic Poulain <loic.poulain@...aro.org>

Some MHI device drivers need to stop the channels in their driver
remove callback (e.g. module unloading), but the unprepare function
is aborted because MHI core moved the channels to suspended state
prior calling driver remove callback. This prevents the driver to
send a proper MHI RESET CHAN command to the device. Device is then
unaware of the stopped state of these channels.

This causes issue when driver tries to start the channels again (e.g.
module is reloaded), since device considers channels as already
started (inconsistent state).

Fix this by allowing channel reset when channel is suspended.

Signed-off-by: Loic Poulain <loic.poulain@...aro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Reviewed-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/bus/mhi/core/main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 2cff5ddff225..cea5eab83f48 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -1224,7 +1224,8 @@ static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
 	/* no more processing events for this channel */
 	mutex_lock(&mhi_chan->mutex);
 	write_lock_irq(&mhi_chan->lock);
-	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED) {
+	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
+	    mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
 		write_unlock_irq(&mhi_chan->lock);
 		mutex_unlock(&mhi_chan->mutex);
 		return;
-- 
2.25.1