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References: <20201102181144.3469197-1-swboyd@chromium.org> <20201102181144.3469197-4-swboyd@chromium.org> <YFKc23MwUQAosCs8@pendragon.ideasonboard.com>
Subject: Re: [PATCH v3 3/4] drm/bridge: ti-sn65dsi86: Read EDID blob over DDC
From:   Stephen Boyd <swboyd@chromium.org>
Cc:     Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Jonas Karlman <jonas@kwiboo.se>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org,
        Douglas Anderson <dianders@chromium.org>,
        Sean Paul <seanpaul@chromium.org>
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date:   Mon, 22 Mar 2021 20:17:55 -0700
Message-ID: <161646947526.2972785.6883720652669260316@swboyd.mtv.corp.google.com>
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Quoting Laurent Pinchart (2021-03-17 17:20:43)
> Hi Stephen,
>=20
> Reviving a bit of an old thread, for a question.
>=20
> On Mon, Nov 02, 2020 at 10:11:43AM -0800, Stephen Boyd wrote:
> > @@ -265,6 +267,23 @@ connector_to_ti_sn_bridge(struct drm_connector *co=
nnector)
> >  static int ti_sn_bridge_connector_get_modes(struct drm_connector *conn=
ector)
> >  {
> >       struct ti_sn_bridge *pdata =3D connector_to_ti_sn_bridge(connecto=
r);
> > +     struct edid *edid =3D pdata->edid;
> > +     int num, ret;
> > +
> > +     if (!edid) {
> > +             pm_runtime_get_sync(pdata->dev);
> > +             edid =3D pdata->edid =3D drm_get_edid(connector, &pdata->=
aux.ddc);
> > +             pm_runtime_put(pdata->dev);
>=20
> Is there any specific reason to use the indirect access method, compared
> to the direct method that translates access to an I2C ancillary address
> to an I2C-over-AUX transaction (see page 20 of SLLSEH2B) ? The direct
> method seems it would be more efficient.
>=20

No I don't think it matters. I was just using the existing support code
that Sean wrote instead of digging into the details. Maybe Sean ran into
something earlier and abandoned that approach?