linux-kernel - Re: [PATCH v2 1/1] drm/bridge: anx7625: Tune K value for IVO panel

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Date:   Fri, 6 Aug 2021 11:42:26 +0200
From:   Robert Foss <robert.foss@...aro.org>
To:     Xin Ji <xji@...logixsemi.com>
Cc:     Nicolas Boichat <drinkcat@...gle.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>, Torsten Duwe <duwe@....de>,
        Vasily Khoruzhick <anarsoul@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bernie Liang <bliang@...logixsemi.com>,
        Qilin Wen <qwen@...logixsemi.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        devel@...verdev.osuosl.org
Subject: Re: [PATCH v2 1/1] drm/bridge: anx7625: Tune K value for IVO panel

Hey Xin,

Thanks for implementing the suggestion so quickly.

Can you send this version of the patch out as v2? Versioning is
important and both tools and processes break if different versions
aren't submitted in different emails.

On Fri, 6 Aug 2021 at 11:35, Xin Ji <xji@...logixsemi.com> wrote:
>
> IVO panel require less input video clock variation than video clock
> variation in DP CTS spec.
>
> This patch decreases the K value of ANX7625 which will shrink eDP Tx
> video clock variation to meet IVO panel's requirement.
>
> Acked-by: Sam Ravnborg <sam@...nborg.org>
> Signed-off-by: Xin Ji <xji@...logixsemi.com>
> ---
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 24 ++++++++++++++++++++---
>  drivers/gpu/drm/bridge/analogix/anx7625.h |  4 +++-
>  2 files changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index a3d82377066b..9b9e3984dd38 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -384,6 +384,25 @@ static int anx7625_odfc_config(struct anx7625_data *ctx,
>         return ret;
>  }
>
> +/*
> + * The MIPI source video data exist large variation (e.g. 59Hz ~ 61Hz),
> + * anx7625 defined K ratio for matching MIPI input video clock and
> + * DP output video clock. Increase K value can match bigger video data
> + * variation. IVO panel has small variation than DP CTS spec, need
> + * decrease the K value.
> + */
> +static int anx7625_set_k_value(struct anx7625_data *ctx)
> +{
> +       struct edid *edid = (struct edid *)ctx->slimport_edid_p.edid_raw_data;
> +
> +       if (edid->mfg_id[0] == IVO_MID0 && edid->mfg_id[1] == IVO_MID1)
> +               return anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +                                        MIPI_DIGITAL_ADJ_1, 0x3B);
> +
> +       return anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> +                                MIPI_DIGITAL_ADJ_1, 0x3D);
> +}
> +
>  static int anx7625_dsi_video_timing_config(struct anx7625_data *ctx)
>  {
>         struct device *dev = &ctx->client->dev;
> @@ -470,9 +489,8 @@ static int anx7625_dsi_video_timing_config(struct anx7625_data *ctx)
>                         MIPI_PLL_N_NUM_15_8, (n >> 8) & 0xff);
>         ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client, MIPI_PLL_N_NUM_7_0,
>                         (n & 0xff));
> -       /* Diff */
> -       ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p1_client,
> -                       MIPI_DIGITAL_ADJ_1, 0x3D);
> +
> +       anx7625_set_k_value(ctx);
>
>         ret |= anx7625_odfc_config(ctx, post_divider - 1);
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.h b/drivers/gpu/drm/bridge/analogix/anx7625.h
> index 034c3840028f..6dcf64c703f9 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.h
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.h
> @@ -210,7 +210,9 @@
>  #define  MIPI_VIDEO_STABLE_CNT           0x0A
>
>  #define  MIPI_LANE_CTRL_10               0x0F
> -#define  MIPI_DIGITAL_ADJ_1   0x1B
> +#define  MIPI_DIGITAL_ADJ_1     0x1B
> +#define  IVO_MID0               0x26
> +#define  IVO_MID1               0xCF
>
>  #define  MIPI_PLL_M_NUM_23_16   0x1E
>  #define  MIPI_PLL_M_NUM_15_8    0x1F
> --
> 2.25.1
>