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Message-ID: <8fbe44af-8da3-4554-ac2b-5db58003449e@collabora.com>
Date: Thu, 18 Jul 2024 12:09:31 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: jason-jh.lin@...iatek.com, Jassi Brar <jassisinghbrar@...il.com>,
CK Hu <ck.hu@...iatek.com>
Cc: Jassi Brar <jaswinder.singh@...aro.org>,
Matthias Brugger <matthias.bgg@...il.com>,
Singo Chang <singo.chang@...iatek.com>, Nancy Lin <nancy.lin@...iatek.com>,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org,
Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v2] mailbox: mtk-cmdq: Move
devm_mbox_controller_register() after devm_pm_runtime_enable()
Il 18/07/24 10:38, Jason-JH.Lin via B4 Relay ha scritto:
> From: "Jason-JH.Lin" <jason-jh.lin@...iatek.com>
>
> When mtk-cmdq unbinds, a WARN_ON message with condition
> pm_runtime_get_sync() < 0 occurs.
>
> According to the call tracei below:
> cmdq_mbox_shutdown
> mbox_free_channel
> mbox_controller_unregister
> __devm_mbox_controller_unregister
> ...
>
> The root cause can be deduced to be calling pm_runtime_get_sync() after
> calling pm_runtime_disable() as observed below:
> 1. CMDQ driver uses devm_mbox_controller_register() in cmdq_probe()
> to bind the cmdq device to the mbox_controller, so
> devm_mbox_controller_unregister() will automatically unregister
> the device bound to the mailbox controller when the device-managed
> resource is removed. That means devm_mbox_controller_unregister()
> and cmdq_mbox_shoutdown() will be called after cmdq_remove().
> 2. CMDQ driver also uses devm_pm_runtime_enable() in cmdq_probe() after
> devm_mbox_controller_register(), so that devm_pm_runtime_disable()
> will be called after cmdq_remove(), but before
> devm_mbox_controller_unregister().
>
> To fix this problem, cmdq_probe() needs to move
> devm_mbox_controller_register() after devm_pm_runtime_enable() to make
> devm_pm_runtime_disable() be called after
> devm_mbox_controller_unregister().
>
> Fixes: 623a6143a845 ("mailbox: mediatek: Add Mediatek CMDQ driver")
> Signed-off-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
> ---
> When mtk-cmdq unbinds, a WARN_ON message with condition
> pm_runtime_get_sync() < 0 occurs.
>
> According to the call tracei below:
> cmdq_mbox_shutdown
> mbox_free_channel
> mbox_controller_unregister
> __devm_mbox_controller_unregister
> ...
>
> The root cause can be deduced to be calling pm_runtime_get_sync() after
> calling pm_runtime_disable() as observed below:
> 1. CMDQ driver uses devm_mbox_controller_register() in cmdq_probe()
> to bind the cmdq device to the mbox_controller, so
> devm_mbox_controller_unregister() will automatically unregister
> the device bound to the mailbox controller when the device-managed
> resource is removed. That means devm_mbox_controller_unregister()
> and cmdq_mbox_shoutdown() will be called after cmdq_remove().
> 2. CMDQ driver also uses devm_pm_runtime_enable() in cmdq_probe() after
> devm_mbox_controller_register(), so that devm_pm_runtime_disable()
> will be called after cmdq_remove(), but before
> devm_mbox_controller_unregister().
>
> To fix this problem, cmdq_probe() needs to move
> devm_mbox_controller_register() after devm_pm_runtime_enable() to make
> devm_pm_runtime_disable() be called after
> devm_mbox_controller_unregister().
>
> Change-Id: I4f0e68eac5186fe8041ea2f16c8e852d52d71cb0
> ---
> Changes in v2:
> - Change to move the calling sequence of devm_mbox_controller_register()
> and devm_pm_runtime_enable().
> - Link to v1: https://lore.kernel.org/r/20240613150626.25280-1-jason-jh.lin@mediatek.com
> ---
> drivers/mailbox/mtk-cmdq-mailbox.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
> index f1dfce9e27f5..002003c3970a 100644
> --- a/drivers/mailbox/mtk-cmdq-mailbox.c
> +++ b/drivers/mailbox/mtk-cmdq-mailbox.c
> @@ -370,6 +370,8 @@ static void cmdq_remove(struct platform_device *pdev)
> {
> struct cmdq *cmdq = platform_get_drvdata(pdev);
>
> + devm_mbox_controller_unregister(&pdev->dev, &cmdq->mbox);
...if you moved devm_mbox_controller_register() after devm_pm_runtime_enable(),
this means that the teardown sequence will disable pm runtime after unregistering
the mbox controller, so why do you need to call devm_mbox_controller_unregister()
manually here?
Cheers,
Angelo
> +
> if (cmdq->pdata->sw_ddr_en)
> cmdq_sw_ddr_enable(cmdq, false);
>
> @@ -689,12 +691,6 @@ static int cmdq_probe(struct platform_device *pdev)
> cmdq->mbox.chans[i].con_priv = (void *)&cmdq->thread[i];
> }
>
> - err = devm_mbox_controller_register(dev, &cmdq->mbox);
> - if (err < 0) {
> - dev_err(dev, "failed to register mailbox: %d\n", err);
> - return err;
> - }
> -
> platform_set_drvdata(pdev, cmdq);
>
> WARN_ON(clk_bulk_prepare(cmdq->pdata->gce_num, cmdq->clocks));
> @@ -722,6 +718,12 @@ static int cmdq_probe(struct platform_device *pdev)
> pm_runtime_set_autosuspend_delay(dev, CMDQ_MBOX_AUTOSUSPEND_DELAY_MS);
> pm_runtime_use_autosuspend(dev);
>
> + err = devm_mbox_controller_register(dev, &cmdq->mbox);
> + if (err < 0) {
> + dev_err(dev, "failed to register mailbox: %d\n", err);
> + return err;
> + }
> +
> return 0;
> }
>
>
> ---
> base-commit: 797012914d2d031430268fe512af0ccd7d8e46ef
> change-id: 20240718-mtk-cmdq-fixup-40379650e96b
>
> Best regards,
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