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From:   Guillaume Ranquet <granquet@baylibre.com>
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Date:   Fri, 25 Feb 2022 02:45:43 -0800
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Subject: Re: [PATCH v8 05/19] drm/mediatek: dpi: move dpi limits to board config
To:     Chun-Kuang Hu <chunkuang.hu@kernel.org>
Cc:     Philipp Zabel <p.zabel@pengutronix.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>, deller@gmx.de,
        CK Hu <ck.hu@mediatek.com>, Jitao Shi <jitao.shi@mediatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        "ARM/Mediatek SoC support" <linux-mediatek@lists.infradead.org>,
        DTML <devicetree@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-phy@lists.infradead.org, linux-fbdev@vger.kernel.org
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Quoting Chun-Kuang Hu (2022-02-21 02:46:15)
> Hi, Guillaume:
>
> Guillaume Ranquet <granquet@baylibre.com> =E6=96=BC 2022=E5=B9=B42=E6=9C=
=8818=E6=97=A5 =E9=80=B1=E4=BA=94 =E4=B8=8B=E5=8D=8810:56=E5=AF=AB=E9=81=93=
=EF=BC=9A
> >
> > Add flexibility by moving the dpi limits to the board config
>
> This patch looks good to me. But I would like to know what's this
> limit and why it vary in different SoC. If possible, would you please
> provide more description for this?
>
> Regards,
> Chun-Kuang.
>

Hi Chun-Kuang,

You are right, the commit message is rather vague and deserves more details=
.
I'll have to dig into the documentations I have access to and ask maybe ask
the engineers at mediatek for a detailed description.

Thx,
Guillaume.

> >
> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_dpi.c | 25 ++++++++++++++++---------
> >  1 file changed, 16 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/media=
tek/mtk_dpi.c
> > index 4554e2de14309..4746eb3425674 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > @@ -125,6 +125,7 @@ struct mtk_dpi_conf {
> >         bool edge_sel_en;
> >         const u32 *output_fmts;
> >         u32 num_output_fmts;
> > +       const struct mtk_dpi_yc_limit *limit;
> >  };
> >
> >  static void mtk_dpi_mask(struct mtk_dpi *dpi, u32 offset, u32 val, u32=
 mask)
> > @@ -235,9 +236,10 @@ static void mtk_dpi_config_fb_size(struct mtk_dpi =
*dpi, u32 width, u32 height)
> >         mtk_dpi_mask(dpi, DPI_SIZE, height << VSIZE, VSIZE_MASK);
> >  }
> >
> > -static void mtk_dpi_config_channel_limit(struct mtk_dpi *dpi,
> > -                                        struct mtk_dpi_yc_limit *limit=
)
> > +static void mtk_dpi_config_channel_limit(struct mtk_dpi *dpi)
> >  {
> > +       const struct mtk_dpi_yc_limit *limit =3D dpi->conf->limit;
> > +
> >         mtk_dpi_mask(dpi, DPI_Y_LIMIT, limit->y_bottom << Y_LIMINT_BOT,
> >                      Y_LIMINT_BOT_MASK);
> >         mtk_dpi_mask(dpi, DPI_Y_LIMIT, limit->y_top << Y_LIMINT_TOP,
> > @@ -449,7 +451,6 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi)
> >  static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
> >                                     struct drm_display_mode *mode)
> >  {
> > -       struct mtk_dpi_yc_limit limit;
> >         struct mtk_dpi_polarities dpi_pol;
> >         struct mtk_dpi_sync_param hsync;
> >         struct mtk_dpi_sync_param vsync_lodd =3D { 0 };
> > @@ -484,11 +485,6 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi=
 *dpi,
> >         dev_dbg(dpi->dev, "Got  PLL %lu Hz, pixel clock %lu Hz\n",
> >                 pll_rate, vm.pixelclock);
> >
> > -       limit.c_bottom =3D 0x0010;
> > -       limit.c_top =3D 0x0FE0;
> > -       limit.y_bottom =3D 0x0010;
> > -       limit.y_top =3D 0x0FE0;
> > -
> >         dpi_pol.ck_pol =3D MTK_DPI_POLARITY_FALLING;
> >         dpi_pol.de_pol =3D MTK_DPI_POLARITY_RISING;
> >         dpi_pol.hsync_pol =3D vm.flags & DISPLAY_FLAGS_HSYNC_HIGH ?
> > @@ -536,7 +532,7 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi =
*dpi,
> >         else
> >                 mtk_dpi_config_fb_size(dpi, vm.hactive, vm.vactive);
> >
> > -       mtk_dpi_config_channel_limit(dpi, &limit);
> > +       mtk_dpi_config_channel_limit(dpi);
> >         mtk_dpi_config_bit_num(dpi, dpi->bit_num);
> >         mtk_dpi_config_channel_swap(dpi, dpi->channel_swap);
> >         mtk_dpi_config_yc_map(dpi, dpi->yc_map);
> > @@ -790,12 +786,20 @@ static const u32 mt8183_output_fmts[] =3D {
> >         MEDIA_BUS_FMT_RGB888_2X12_BE,
> >  };
> >
> > +static const struct mtk_dpi_yc_limit mtk_dpi_limit =3D {
> > +       .c_bottom =3D 0x0010,
> > +       .c_top =3D 0x0FE0,
> > +       .y_bottom =3D 0x0010,
> > +       .y_top =3D 0x0FE0,
> > +};
> > +
> >  static const struct mtk_dpi_conf mt8173_conf =3D {
> >         .cal_factor =3D mt8173_calculate_factor,
> >         .reg_h_fre_con =3D 0xe0,
> >         .max_clock_khz =3D 300000,
> >         .output_fmts =3D mt8173_output_fmts,
> >         .num_output_fmts =3D ARRAY_SIZE(mt8173_output_fmts),
> > +       .limit =3D &mtk_dpi_limit,
> >  };
> >
> >  static const struct mtk_dpi_conf mt2701_conf =3D {
> > @@ -805,6 +809,7 @@ static const struct mtk_dpi_conf mt2701_conf =3D {
> >         .max_clock_khz =3D 150000,
> >         .output_fmts =3D mt8173_output_fmts,
> >         .num_output_fmts =3D ARRAY_SIZE(mt8173_output_fmts),
> > +       .limit =3D &mtk_dpi_limit,
> >  };
> >
> >  static const struct mtk_dpi_conf mt8183_conf =3D {
> > @@ -813,6 +818,7 @@ static const struct mtk_dpi_conf mt8183_conf =3D {
> >         .max_clock_khz =3D 100000,
> >         .output_fmts =3D mt8183_output_fmts,
> >         .num_output_fmts =3D ARRAY_SIZE(mt8183_output_fmts),
> > +       .limit =3D &mtk_dpi_limit,
> >  };
> >
> >  static const struct mtk_dpi_conf mt8192_conf =3D {
> > @@ -821,6 +827,7 @@ static const struct mtk_dpi_conf mt8192_conf =3D {
> >         .max_clock_khz =3D 150000,
> >         .output_fmts =3D mt8173_output_fmts,
> >         .num_output_fmts =3D ARRAY_SIZE(mt8173_output_fmts),
> > +       .limit =3D &mtk_dpi_limit,
> >  };
> >
> >  static int mtk_dpi_probe(struct platform_device *pdev)
> > --
> > 2.34.1
> >