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

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Date:   Wed, 15 May 2019 14:05:03 -0400
From:   Sean Paul <sean@...rly.run>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Sean Paul <sean@...rly.run>, Heiko Stuebner <heiko@...ech.de>,
        Sandy Huang <hjc@...k-chips.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        "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>,
        Zheng Yang <zhengyang@...k-chips.com>,
        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>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH 1/2] drm: bridge: dw-hdmi: Add hooks for suspend/resume

On Wed, May 15, 2019 at 11:01:26AM -0700, Doug Anderson wrote:
> Hi,
> 
> On Wed, May 15, 2019 at 10:58 AM Sean Paul <sean@...rly.run> wrote:
> 
> > On Thu, May 02, 2019 at 03:38:07PM -0700, Douglas Anderson 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.
> > >
> > > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> > > ---
> > >
> > >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 21 +++++++++++++++++++++
> > >  include/drm/bridge/dw_hdmi.h              |  3 +++
> > >  2 files changed, 24 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > > index db761329a1e3..4b38bfd43e59 100644
> > > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > > @@ -2780,6 +2780,27 @@ void dw_hdmi_unbind(struct dw_hdmi *hdmi)
> > >  }
> > >  EXPORT_SYMBOL_GPL(dw_hdmi_unbind);
> > >
> > > +int dw_hdmi_suspend(struct dw_hdmi *hdmi)
> > > +{
> > > +     return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(dw_hdmi_suspend);
> > > +
> > > +int dw_hdmi_resume(struct dw_hdmi *hdmi)
> > > +{
> > > +     initialize_hdmi_ih_mutes(hdmi);
> > > +
> > > +     dw_hdmi_setup_i2c(hdmi);
> > > +     if (hdmi->i2c)
> > > +             dw_hdmi_i2c_init(hdmi);
> > > +
> > > +     if (hdmi->phy.ops->setup_hpd)
> > > +             hdmi->phy.ops->setup_hpd(hdmi, hdmi->phy.data);
> > > +
> > > +     return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(dw_hdmi_resume);
> >
> > Both patches look good to me, I'd probably prefer to just smash them together,
> > but meh.
> >
> > If no one more authoritative chimes in, I'll apply them to -misc in a few days.
> 
> Sure.  I can smash them and re-post or you can smash them for me or we
> can keep them as-is.  I originally separated because I wasn't sure if
> they'd eventually go through different trees.  Just let me know!  :-)

Definitely no need to repost. It's entirely possible Andrzej or Heiko prefer to
have the dw-hdmi stuff broken out anyways. My opinion is of little value here :)

Sean

> 
> -Doug

-- 
Sean Paul, Software Engineer, Google / Chromium OS