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From:   Fabio Estevam <festevam@gmail.com>
Date:   Tue, 18 Jun 2019 12:09:23 -0300
Message-ID: <CAOMZO5BY8JcLNMCRCC_d=emy8HR6kE=dB9f5qfZ=ci_c+Jak0w@mail.gmail.com>
Subject: Re: [IMX] [DRM]: suspend/resume support
To:     Pintu Agarwal <pintu.ping@gmail.com>
Cc:     open list <linux-kernel@vger.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        Kernelnewbies <kernelnewbies@kernelnewbies.org>,
        linux-pm@vger.kernel.org
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On Tue, Jun 18, 2019 at 11:46 AM Pintu Agarwal <pintu.ping@gmail.com> wrote:

> Thank you so much for your reply.
> Yes, I already checked the latest mainline kernel changes until 5.2-**.
> I see that there are many cleanup related changes, but still I see
> that suspend/resume functions are missing in dw_hdmi-imx driver.

Please see this recently submitted patch:
https://lore.kernel.org/patchwork/patch/1084057/

> So, I am trying to implement myself.
> Also, I see that suspend/resume is missing even in :
> drivers/gpu/drm/imx/ipuv3-crtc.c
> I am trying this also (not sure if we need this as well).
>
> Can you point out some specific patches which can be helpful ?
>
> Currently, what I observed is that hdmi bind() functions are not getting called.
> Not sure who is responsible for triggering this bind function.
> Or, irq remains disabled after resume, and we need to enable it back
> again (but how ?)
> Or, we may need to enable vblank events and thus irqs can be enabled.
>
> So, I am exploring many possibilities.
> If you have any suggestions please let me know.

The suggestion I have is to try to use latest mainline kernel. If you
see any issues with it, please report.

The combination you mentioned in a prior thread (kernel 3.10 +
backported drm patches 4.9) is not really something the community can
help you.