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From:   Ricardo Ribalda <ribalda@chromium.org>
Date:   Sat, 26 Nov 2022 00:32:22 +0100
Subject: [PATCH v2] mailbox: mtk-cmdq: Do not request irq until we are ready
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Message-Id: <20221125-mtk-mailbox-v2-0-886f70c7173c@chromium.org>
To:     Matthias Brugger <matthias.bgg@gmail.com>,
        Jassi Brar <jassisinghbrar@gmail.com>
Cc:     linux-mediatek@lists.infradead.org,
        Ricardo Ribalda <ribalda@chromium.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Precedence: bulk

If the system comes from kexec() the peripheral might trigger an IRQ
befoe we are ready for it. Triggering a crash due to an access to
invalid memory.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
To: Jassi Brar <jassisinghbrar@gmail.com>
To: Matthias Brugger <matthias.bgg@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mediatek@lists.infradead.org
---
Changes in v2:
- I have managed to repro a different panic. Moving the irq enabling to the very end of probe.
- Link to v1: https://lore.kernel.org/r/20221125-mtk-mailbox-v1-0-2e3ee120850c@chromium.org
---
 drivers/mailbox/mtk-cmdq-mailbox.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
index 9465f9081515..9ff4f89a55c0 100644
--- a/drivers/mailbox/mtk-cmdq-mailbox.c
+++ b/drivers/mailbox/mtk-cmdq-mailbox.c
@@ -545,12 +545,6 @@ static int cmdq_probe(struct platform_device *pdev)
 	cmdq->control_by_sw = plat_data->control_by_sw;
 	cmdq->gce_num = plat_data->gce_num;
 	cmdq->irq_mask = GENMASK(cmdq->thread_nr - 1, 0);
-	err = devm_request_irq(dev, cmdq->irq, cmdq_irq_handler, IRQF_SHARED,
-			       "mtk_cmdq", cmdq);
-	if (err < 0) {
-		dev_err(dev, "failed to register ISR (%d)\n", err);
-		return err;
-	}
 
 	dev_dbg(dev, "cmdq device: addr:0x%p, va:0x%p, irq:%d\n",
 		dev, cmdq->base, cmdq->irq);
@@ -617,6 +611,13 @@ static int cmdq_probe(struct platform_device *pdev)
 
 	cmdq_init(cmdq);
 
+	err = devm_request_irq(dev, cmdq->irq, cmdq_irq_handler, IRQF_SHARED,
+			       "mtk_cmdq", cmdq);
+	if (err < 0) {
+		dev_err(dev, "failed to register ISR (%d)\n", err);
+		return err;
+	}
+
 	return 0;
 }
 

---
base-commit: 4312098baf37ee17a8350725e6e0d0e8590252d4
change-id: 20221125-mtk-mailbox-ba6cbd1d91b6

Best regards,
-- 
Ricardo Ribalda <ribalda@chromium.org>