linux-kernel - Re: [PATCH v2 1/2] drm: bridge: dw-hdmi: Add hook for resume

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Date:   Mon, 3 Jun 2019 14:37:07 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Laurent Pinchart <Laurent.pinchart@...asonboard.com>
Cc:     "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        Sean Paul <seanpaul@...omium.org>,
        Jonas Karlman <jonas@...boo.se>,
        Sam Ravnborg <sam@...nborg.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Heiko Stuebner <heiko@...ech.de>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Sandy Huang <hjc@...k-chips.com>
Subject: Re: [PATCH v2 1/2] drm: bridge: dw-hdmi: Add hook for resume

Laurent,

On Thu, May 16, 2019 at 2:40 PM Douglas Anderson <dianders@...omium.org> wrote:
>
> On Rockchip rk3288-based Chromebooks when you do a suspend/resume
> cycle:
>
> 1. You lose the ability to detect an HDMI device being plugged in.
>
> 2. If you're using the i2c bus built in to dw_hdmi then it stops
> working.
>
> Let's add a hook to the core dw-hdmi driver so that we can call it in
> dw_hdmi-rockchip in the next commit.
>
> NOTE: the exact set of steps I've done here in resume come from
> looking at the normal dw_hdmi init sequence in upstream Linux plus the
> sequence that we did in downstream Chrome OS 3.14.  Testing show that
> it seems to work, but if an extra step is needed or something here is
> not needed we could improve it.
>
> As part of this change we'll refactor the hardware init bits of
> dw-hdmi to happen all in one function and all at the same time.  Since
> we need to init the interrupt mutes before we request the IRQ, this
> means moving the hardware init earlier in the function, but there
> should be no problems with that.  Also as part of this we now
> unconditionally init the "i2c" parts of dw-hdmi, but again that ought
> to be fine.
>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
>
> Changes in v2:
> - No empty stub for suspend (Laurent)
> - Refactor to use the same code in probe and resume (Laurent)
> - Unconditionally init i2c (seems OK + needed before hdmi->i2c init)
> - Combine "init" of i2c and "setup" of i2c (no reason to split)

Are you happy with this now?  Even if you feel like you don't want to
give it a full Reviewed-by, it'd good if you could confirm that I
handled your suggestions properly.

Thanks!  :-)

-Doug