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Message-ID: <b0037c9f-588b-4eb8-6415-0fe75bed264f@collabora.com>
Date:   Tue, 26 Sep 2023 10:06:35 +0200
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Subject: Re: [PATCH] drm/panel: Move AUX B116XW03 out of panel-edp back to
 panel-simple
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To:     Douglas Anderson <dianders@chromium.org>,
        dri-devel@lists.freedesktop.org
Cc:     linux-samsung-soc@vger.kernel.org,
        Hsin-Yi Wang <hsinyi@chromium.org>, matthias.bgg@gmail.com,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-mediatek@lists.infradead.org,
        Marek Szyprowski <m.szyprowski@samsung.com>, airlied@gmail.com,
        daniel@ffwll.ch, jitao.shi@mediatek.com, linus.walleij@linaro.org,
        linux-kernel@vger.kernel.org, neil.armstrong@linaro.org,
        quic_jesszhan@quicinc.com, sam@ravnborg.org
References: <20230925150010.1.Iff672233861bcc4cf25a7ad0a81308adc3bda8a4@changeid>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <20230925150010.1.Iff672233861bcc4cf25a7ad0a81308adc3bda8a4@changeid>
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Precedence: bulk

Il 26/09/23 00:00, Douglas Anderson ha scritto:
> In commit 5f04e7ce392d ("drm/panel-edp: Split eDP panels out of
> panel-simple") I moved a pile of panels out of panel-simple driver
> into the newly created panel-edp driver. One of those panels, however,
> shouldn't have been moved.
> 
> As is clear from commit e35e305eff0f ("drm/panel: simple: Add AUO
> B116XW03 panel support"), AUX B116XW03 is an LVDS panel. It's used in
> exynos5250-snow and exynos5420-peach-pit where it's clear that the
> panel is hooked up with LVDS. Furthermore, searching for datasheets I
> found one that makes it clear that this panel is LVDS.
> 
> As far as I can tell, I got confused because in commit 88d3457ceb82
> ("drm/panel: auo,b116xw03: fix flash backlight when power on") Jitao
> Shi added "DRM_MODE_CONNECTOR_eDP". That seems wrong. Looking at the
> downstream ChromeOS trees, it seems like some Mediatek boards are
> using a panel that they call "auo,b116xw03" that's an eDP panel. The
> best I can guess is that they actually have a different panel that has
> similar timing. If so then the proper panel should be used or they
> should switch to the generic "edp-panel" compatible.
> 
> When moving this back to panel-edp, I wasn't sure what to use for
> .bus_flags and .bus_format and whether to add the extra "enable" delay
> from commit 88d3457ceb82 ("drm/panel: auo,b116xw03: fix flash
> backlight when power on"). I've added formats/flags/delays based on my
> (inexpert) analysis of the datasheet. These are untested.
> 
> NOTE: if/when this is backported to stable, we might run into some
> trouble. Specifically, before 474c162878ba ("arm64: dts: mt8183:
> jacuzzi: Move panel under aux-bus") this panel was used by
> "mt8183-kukui-jacuzzi", which assumed it was an eDP panel. I don't
> know what to suggest for that other than someone making up a bogus
> panel for jacuzzi that's just for the stable channel.
> 
> Fixes: 88d3457ceb82 ("drm/panel: auo,b116xw03: fix flash backlight when power on")
> Fixes: 5f04e7ce392d ("drm/panel-edp: Split eDP panels out of panel-simple")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> I haven't had a snow or peach-pit hooked up for debugging / testing
> for years. I presume that they must be broken and hope that this fixes
> them.

We could avoid backport breakages by avoiding to backport this to any kernel
that doesn't contain commit 474c162878ba ("arm64: dts: mt8183: jacuzzi: Move
panel under aux-bus")... because creating a dummy panel to get two wrongs
right is definitely not ok.

Cheers,
Angelo

> 
>   drivers/gpu/drm/panel/panel-edp.c    | 29 -----------------------
>   drivers/gpu/drm/panel/panel-simple.c | 35 ++++++++++++++++++++++++++++
>   2 files changed, 35 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> index feb665df35a1..95c8472d878a 100644
> --- a/drivers/gpu/drm/panel/panel-edp.c
> +++ b/drivers/gpu/drm/panel/panel-edp.c
> @@ -976,32 +976,6 @@ static const struct panel_desc auo_b116xak01 = {
>   	},
>   };
>   
> -static const struct drm_display_mode auo_b116xw03_mode = {
> -	.clock = 70589,
> -	.hdisplay = 1366,
> -	.hsync_start = 1366 + 40,
> -	.hsync_end = 1366 + 40 + 40,
> -	.htotal = 1366 + 40 + 40 + 32,
> -	.vdisplay = 768,
> -	.vsync_start = 768 + 10,
> -	.vsync_end = 768 + 10 + 12,
> -	.vtotal = 768 + 10 + 12 + 6,
> -	.flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
> -};
> -
> -static const struct panel_desc auo_b116xw03 = {
> -	.modes = &auo_b116xw03_mode,
> -	.num_modes = 1,
> -	.bpc = 6,
> -	.size = {
> -		.width = 256,
> -		.height = 144,
> -	},
> -	.delay = {
> -		.enable = 400,
> -	},
> -};
> -
>   static const struct drm_display_mode auo_b133han05_mode = {
>   	.clock = 142600,
>   	.hdisplay = 1920,
> @@ -1725,9 +1699,6 @@ static const struct of_device_id platform_of_match[] = {
>   	}, {
>   		.compatible = "auo,b116xa01",
>   		.data = &auo_b116xak01,
> -	}, {
> -		.compatible = "auo,b116xw03",
> -		.data = &auo_b116xw03,
>   	}, {
>   		.compatible = "auo,b133han05",
>   		.data = &auo_b133han05,
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index bb89e6d047bc..439d26928938 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -919,6 +919,38 @@ static const struct panel_desc auo_b101xtn01 = {
>   	},
>   };
>   
> +static const struct drm_display_mode auo_b116xw03_mode = {
> +	.clock = 70589,
> +	.hdisplay = 1366,
> +	.hsync_start = 1366 + 40,
> +	.hsync_end = 1366 + 40 + 40,
> +	.htotal = 1366 + 40 + 40 + 32,
> +	.vdisplay = 768,
> +	.vsync_start = 768 + 10,
> +	.vsync_end = 768 + 10 + 12,
> +	.vtotal = 768 + 10 + 12 + 6,
> +	.flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
> +};
> +
> +static const struct panel_desc auo_b116xw03 = {
> +	.modes = &auo_b116xw03_mode,
> +	.num_modes = 1,
> +	.bpc = 6,
> +	.size = {
> +		.width = 256,
> +		.height = 144,
> +	},
> +	.delay = {
> +		.prepare = 1,
> +		.enable = 200,
> +		.disable = 200,
> +		.unprepare = 500,
> +	},
> +	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> +	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> +};
> +
>   static const struct display_timing auo_g070vvn01_timings = {
>   	.pixelclock = { 33300000, 34209000, 45000000 },
>   	.hactive = { 800, 800, 800 },
> @@ -4128,6 +4160,9 @@ static const struct of_device_id platform_of_match[] = {
>   	}, {
>   		.compatible = "auo,b101xtn01",
>   		.data = &auo_b101xtn01,
> +	}, {
> +		.compatible = "auo,b116xw03",
> +		.data = &auo_b116xw03,
>   	}, {
>   		.compatible = "auo,g070vvn01",
>   		.data = &auo_g070vvn01,