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References: <20221213150304.4189760-1-robert.foss@linaro.org>
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From:   Amit Pundir <amit.pundir@linaro.org>
Date:   Tue, 13 Dec 2022 22:16:55 +0530
Message-ID: <CAMi1Hd1Ei5SbT8DHacFq6sJXCsjWdeY3OyeE_RnWnkxNp6i9Qw@mail.gmail.com>
Subject: Re: [PATCH v1] drm/bridge: lt9611: Fix PLL being unable to lock
To:     Robert Foss <robert.foss@linaro.org>
Cc:     stable <stable@vger.kernel.org>, andrzej.hajda@intel.com,
        neil.armstrong@linaro.org, Laurent.pinchart@ideasonboard.com,
        jonas@kwiboo.se, jernej.skrabec@gmail.com, airlied@gmail.com,
        daniel@ffwll.ch, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
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On Tue, 13 Dec 2022 at 20:33, Robert Foss <robert.foss@linaro.org> wrote:
>
> This fixes PLL being unable to lock, and is derived from an equivalent
> downstream commit.
>
> Available LT9611 documentation does not list this register, neither does
> LT9611UXC (which is a different chip).
>
> This commit has been confirmed to fix HDMI output on DragonBoard 845c.
>

Cc: <stable@vger.kernel.org>    [v5.10+]
Reviewed-by: Amit Pundir <amit.pundir@linaro.org>

> Suggested-by: Amit Pundir <amit.pundir@linaro.org>
> Signed-off-by: Robert Foss <robert.foss@linaro.org>
> ---
>  drivers/gpu/drm/bridge/lontium-lt9611.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/bridge/lontium-lt9611.c b/drivers/gpu/drm/bridge/lontium-lt9611.c
> index ffcdc8dba3798..3ce4e495aee50 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt9611.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt9611.c
> @@ -259,6 +259,7 @@ static int lt9611_pll_setup(struct lt9611 *lt9611, const struct drm_display_mode
>                 { 0x8126, 0x55 },
>                 { 0x8127, 0x66 },
>                 { 0x8128, 0x88 },
> +               { 0x812a, 0x20 },
>         };
>
>         regmap_multi_reg_write(lt9611->regmap, reg_cfg, ARRAY_SIZE(reg_cfg));
> --
> 2.34.1
>