linux-kernel - [PATCH v1 4/4] bus: mhi: core: Check execution environment for channel before issuing reset

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Message-Id: <1604961850-27671-5-git-send-email-bbhatt@codeaurora.org>
Date:   Mon,  9 Nov 2020 14:44:10 -0800
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     manivannan.sadhasivam@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, loic.poulain@...aro.org,
        linux-kernel@...r.kernel.org, Bhaumik Bhatt <bbhatt@...eaurora.org>
Subject: [PATCH v1 4/4] bus: mhi: core: Check execution environment for channel before issuing reset

A client can attempt to unprepare certain channels for transfer even
after the execution environment they are supposed to run in has changed.
In the event that happens, the device need not be notified of the reset
and the host can proceed with clean up for the channel context and
memory allocated for it on the host.

Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
---
 drivers/bus/mhi/core/main.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 01845c6..1e432d4 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -1323,11 +1323,24 @@ static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
 	/* no more processing events for this channel */
 	mutex_lock(&mhi_chan->mutex);
 
+	if (!(BIT(mhi_cntrl->ee) & mhi_chan->ee_mask)) {
+		dev_err(dev,
+			"Current EE: %s Required EE Mask: 0x%x for chan: %s\n",
+			TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask,
+			mhi_chan->name);
+		goto exit_unprepare_channel;
+	}
+
 	ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
 				       MHI_CH_STATE_TYPE_RESET);
 	if (ret)
 		dev_err(dev, "Failed to reset channel, still resetting\n");
 
+exit_unprepare_channel:
+	write_lock_irq(&mhi_chan->lock);
+	mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
+	write_unlock_irq(&mhi_chan->lock);
+
 	if (!mhi_chan->offload_ch) {
 		mhi_reset_chan(mhi_cntrl, mhi_chan);
 		mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
-- 
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