From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Cc: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
Jacopo Mondi <jacopo+renesas@jmondi.org>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"linux-renesas-soc@vger.kernel.org"
<linux-renesas-soc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Simon Horman <horms@verge.net.au>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Chris Paterson <Chris.Paterson2@renesas.com>,
Biju Das <biju.das@bp.renesas.com>
Subject: Re: [PATCH/RFC 05/12] drm: rcar-du: lvds: Add data swap support
Date: Mon, 5 Aug 2019 13:17:10 +0300 [thread overview]
Message-ID: <20190805101710.GD29747@pendragon.ideasonboard.com> (raw)
In-Reply-To: <TY1PR01MB1770F1B00FEA431E43978FD9C0DA0@TY1PR01MB1770.jpnprd01.prod.outlook.com>
Hi Fabrizio,
On Mon, Aug 05, 2019 at 09:32:42AM +0000, Fabrizio Castro wrote:
> On 02 August 2019 09:06 Laurent Pinchart wrote:
> > On Fri, Aug 02, 2019 at 08:34:02AM +0100, Fabrizio Castro wrote:
> > > When in vertical stripe mode of operation, there is the option
> > > of swapping even data and odd data on the two LVDS interfaces
> > > used to drive the video output.
> > > Add data swap support by exposing a new DT property named
> > > "renesas,swap-data".
> > >
> > > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> > > ---
> > > drivers/gpu/drm/rcar-du/rcar_lvds.c | 23 ++++++++++++++++-------
> > > 1 file changed, 16 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > > index 3aeaf9e..c306fab 100644
> > > --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > > +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > > @@ -69,6 +69,7 @@ struct rcar_lvds {
> > >
> > > struct drm_bridge *companion;
> > > bool dual_link;
> > > + bool stripe_swap_data;
> > > };
> > >
> > > #define bridge_to_rcar_lvds(bridge) \
> > > @@ -439,12 +440,16 @@ static void rcar_lvds_enable(struct drm_bridge *bridge)
> > > rcar_lvds_write(lvds, LVDCHCR, lvdhcr);
> > >
> > > if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK) {
> > > - /*
> > > - * Configure vertical stripe based on the mode of operation of
> > > - * the connected device.
> > > - */
> > > - rcar_lvds_write(lvds, LVDSTRIPE,
> > > - lvds->dual_link ? LVDSTRIPE_ST_ON : 0);
> > > + u32 lvdstripe = 0;
> > > +
> > > + if (lvds->dual_link)
> > > + /*
> > > + * Configure vertical stripe based on the mode of
> > > + * operation of the connected device.
> > > + */
> > > + lvdstripe = LVDSTRIPE_ST_ON | (lvds->stripe_swap_data ?
> > > + LVDSTRIPE_ST_SWAP : 0);
> >
> > Would the following be simpler ?
> >
> > lvdstripe = (lvds->dual_link ? LVDSTRIPE_ST_ON : 0)
> > | (lvds->stripe_swap_data ? LVDSTRIPE_ST_SWAP : 0);
> >
> > > + rcar_lvds_write(lvds, LVDSTRIPE, lvdstripe);
>
> I actually think I need to rework this patch slightly, because the user manual
> says that ST_SWAP is reserved for LVD1STRIPE, so I need to make sure we
> don't set it for LVDS1.
>
> So perhaps, this could translate to something like:
> If (lvds->dual_link)
> lvdstripe = LVDSTRIPE_ST_ON | (<swap-whatever> && lvds->companion) ? LVDSTRIPE_ST_SWAP : 0);
>
> I don't think we should be setting LVDSTRIPE_ST_SWAP without LVDSTRIPE_ST_ON, this solution
> would allow us to test lvds->dual_link only once, and will prevent us from setting LVDSTRIPE_ST_SWAP if
> LVDSTRIPE_ST_ON is not set or if we are touching LVDS1.
>
> What do you think?
I was thinking that lvds->stripe_swap_data should only be set when
lvds->dual_link is set and lvds->companion is non-NULL, so both are
roughly equivalent. It's a detail anyway, it doesn't matter too much.
> > > }
> > >
> > > /*
> > > @@ -770,8 +775,12 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> > > }
> > > }
> > >
> > > - if (lvds->dual_link)
> > > + if (lvds->dual_link) {
> > > + lvds->stripe_swap_data = of_property_read_bool(
> > > + lvds->dev->of_node,
> > > + "renesas,swap-data");
> > > ret = rcar_lvds_parse_dt_companion(lvds);
> > > + }
> >
> > As explained in the review of the corresponding DT bindings, I think
> > this should be queried from the remote device rather than specified in
> > DT.
> >
> > >
> > > done:
> > > of_node_put(local_output);
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2019-08-05 10:17 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 7:33 [PATCH/RFC 00/12] Add dual-LVDS panel support to EK874 Fabrizio Castro
2019-08-02 7:33 ` [PATCH/RFC 01/12] dt-bindings: display: renesas: lvds: RZ/G2E needs renesas,companion too Fabrizio Castro
2019-08-02 7:48 ` Laurent Pinchart
2019-08-02 7:33 ` [PATCH/RFC 02/12] dt-bindings: display: renesas: lvds: Document renesas,swap-data Fabrizio Castro
2019-08-02 7:44 ` Laurent Pinchart
2019-08-05 8:59 ` Fabrizio Castro
2019-08-05 9:35 ` Laurent Pinchart
2019-08-05 10:07 ` Fabrizio Castro
2019-08-02 7:34 ` [PATCH/RFC 03/12] dt-bindings: panel: lvds: Add dual-link LVDS display support Fabrizio Castro
2019-08-02 8:00 ` Laurent Pinchart
2019-08-05 9:02 ` Fabrizio Castro
2019-08-02 7:34 ` [PATCH/RFC 04/12] dt-bindings: display: Add bindings for Advantech IDK-2121WR Fabrizio Castro
2019-08-02 8:03 ` Laurent Pinchart
2019-08-05 9:04 ` Fabrizio Castro
2019-08-02 7:34 ` [PATCH/RFC 05/12] drm: rcar-du: lvds: Add data swap support Fabrizio Castro
2019-08-02 8:06 ` Laurent Pinchart
2019-08-02 9:01 ` Geert Uytterhoeven
2019-08-05 9:32 ` Fabrizio Castro
2019-08-05 10:17 ` Laurent Pinchart [this message]
2019-08-02 7:34 ` [PATCH/RFC 06/12] drm: rcar-du: lvds: Do not look at ports for identifying bridges Fabrizio Castro
2019-08-02 8:08 ` Laurent Pinchart
2019-08-05 9:06 ` Fabrizio Castro
2019-08-02 7:34 ` [PATCH/RFC 07/12] drm: rcar-du: lvds: Add support for dual link panels Fabrizio Castro
2019-08-02 8:20 ` Laurent Pinchart
2019-08-05 9:12 ` Fabrizio Castro
2019-08-05 9:48 ` Laurent Pinchart
2019-08-05 10:07 ` Fabrizio Castro
2019-08-02 7:34 ` [PATCH/RFC 08/12] drm: rcar-du: lvds: Fix bridge_to_rcar_lvds Fabrizio Castro
2019-08-02 8:22 ` Laurent Pinchart
2019-08-05 9:13 ` Fabrizio Castro
2019-08-02 7:34 ` [PATCH/RFC 09/12] drm: rcar-du: lvds: Fix companion's mode Fabrizio Castro
2019-08-02 8:26 ` Laurent Pinchart
2019-08-05 9:15 ` Fabrizio Castro
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