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From:   Eric Anholt <eric@anholt.net>
To:     Sasha Levin <Alexander.Levin@microsoft.com>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable\@vger.kernel.org" <stable@vger.kernel.org>
Cc:     Stefan Schake <stschake@gmail.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: Re: [PATCH AUTOSEL for 4.14 001/100] drm/vc4: Account for interrupts in flight
In-Reply-To: <20180124041414.32065-1-alexander.levin@microsoft.com>
References: <20180124041414.32065-1-alexander.levin@microsoft.com>
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Date:   Thu, 25 Jan 2018 14:30:23 +1100
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Sasha Levin <Alexander.Levin@microsoft.com> writes:

> From: Stefan Schake <stschake@gmail.com>
>
> [ Upstream commit 253696ccd613fbdaa5aba1de44c461a058e0a114 ]
>
> Synchronously disable the IRQ to make the following cancel_work_sync
> invocation effective.
>
> An interrupt in flight could enqueue further overflow mem work. As we
> free the binner BO immediately following vc4_irq_uninstall this caused
> a NULL pointer dereference in the work callback vc4_overflow_mem_work.
>
> Link: https://github.com/anholt/linux/issues/114
> Signed-off-by: Stefan Schake <stschake@gmail.com>
> Fixes: d5b1a78a772f ("drm/vc4: Add support for drawing 3D frames.")
> Signed-off-by: Eric Anholt <eric@anholt.net>
> Reviewed-by: Eric Anholt <eric@anholt.net>
> Link: https://patchwork.freedesktop.org/patch/msgid/1510275907-993-2-git-=
send-email-stschake@gmail.com
> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>

We found a bug, and this patch also needs:

commit ce9caf2f79a5aa170a4b6456a03db639eed9c988 (tag: drm-misc-fixes-2018-0=
1-08)
Author: Stefan Schake <stschake@gmail.com>
Date:   Fri Dec 29 17:05:43 2017 +0100

    drm/vc4: Move IRQ enable to PM path
=20=20=20=20
    We were calling enable_irq on bind, where it was already enabled previo=
usly
    by the IRQ helper. Additionally, dev->irq is not set correctly until af=
ter
    postinstall and so was always zero here, triggering a warning in 4.15.
    Fix both by moving the enable to the power management resume path, wher=
e we
    know there was a previous disable invocation during suspend.
=20=20=20=20
    Fixes: 253696ccd613 ("drm/vc4: Account for interrupts in flight")
    Signed-off-by: Stefan Schake <stschake@gmail.com>
    Signed-off-by: Eric Anholt <eric@anholt.net>
    Link: https://patchwork.freedesktop.org/patch/msgid/1514563543-32511-1-=
git-send-email-stschake@gmail.com
    Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
    Reviewed-by: Eric Anholt <eric@anholt.net>

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