linux-kernel - Re: [PATCH v4 5/5] drm/panel: samsung-s6e88a0-ams427ap24: Add flip option

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Message-ID: <CACRpkdY-5G0uui1xKnKFbxVs6couGUy14CH+KrHH=j5LfDsb_g@mail.gmail.com>
Date: Mon, 28 Oct 2024 13:47:33 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Jakob Hauser <jahau@...ketmail.com>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Thierry Reding <thierry.reding@...il.com>, 
	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>, 
	Andrzej Hajda <andrzej.hajda@...el.com>, dri-devel@...ts.freedesktop.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v4 5/5] drm/panel: samsung-s6e88a0-ams427ap24: Add flip option

On Mon, Oct 28, 2024 at 12:42 AM Jakob Hauser <jahau@...ketmail.com> wrote:

> The way of implementing a flip option follows the existing
> panel-samsung-s6e8aa0.c [1][2][3].
>
> The value to flip the screen is taken from a downstream kernel file of
> a similar but older panel [4]. The mipi clock [5] for the new panel
> samsung-s6e88a0-ams427ap24 matches 461 MHz and a hardware read-out of the
> 0xcb values corresponds to revision R01 of that older panel [6]. Although
> for samsung-s6e88a0-ams427ap24 that's in non-flipped state while in this
> older driver it seems to be the other way around. Further up there is a
> hint [7] basically saying for revision R01 to change the first word of the
> 0xcb command from 0x06 to 0x0e, which is actually setting BIT(3) of that
> word. This causes a horizontal flip.
>
> [1] https://github.com/torvalds/linux/blob/v6.11/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c#L103
> [2] https://github.com/torvalds/linux/blob/v6.11/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c#L207-L211
> [3] https://github.com/torvalds/linux/blob/v6.11/drivers/gpu/drm/panel/panel-samsung-s6e8aa0.c#L954-L974
> [4] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c
> [5] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c#L2027-L2028
> [6] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c#L137-L151
> [7] https://github.com/LineageOS/android_kernel_samsung_msm8930-common/blob/lineage-15.1/drivers/video/msm/mipi_samsung_oled_video_qhd_pt-8930.c#L66-L74
>
> Signed-off-by: Jakob Hauser <jahau@...ketmail.com>
> Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>

Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij