linux-kernel - Re: [PATCH v3 10/10] arm64: dts: renesas: gray-hawk-single: Add DisplayPort support

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Message-ID: <a9e21786-af00-4464-b144-5be13e120287@ideasonboard.com>
Date: Mon, 16 Dec 2024 19:02:08 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Geert Uytterhoeven <geert+renesas@...der.be>,
 Magnus Damm <magnus.damm@...il.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, LUU HOAI <hoai.luu.ub@...esas.com>,
 Jagan Teki <jagan@...rulasolutions.com>, Sam Ravnborg <sam@...nborg.org>,
 Biju Das <biju.das.jz@...renesas.com>, dri-devel@...ts.freedesktop.org,
 linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
 linux-clk@...r.kernel.org
Subject: Re: [PATCH v3 10/10] arm64: dts: renesas: gray-hawk-single: Add
 DisplayPort support

Hi,

On 16/12/2024 17:15, Tomi Valkeinen wrote:
> Hi,
> 
> On 16/12/2024 15:33, Geert Uytterhoeven wrote:
>> Hi Tomi,
>>
>> On Fri, Dec 6, 2024 at 10:33 AM Tomi Valkeinen
>> <tomi.valkeinen@...asonboard.com> wrote:
>>> From: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
>>>
>>> Add support for the mini DP output on the Gray Hawk board.
>>>
>>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
>>> Reviewed-by: Laurent Pinchart 
>>> <laurent.pinchart+renesas@...asonboard.com>
>>> Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>
>>
>> Thanks for your patch, which is now commit b1000645dc29701f
>> ("arm64: dts: renesas: gray-hawk-single: Add DisplayPort support")
>> in renesas-devel/renesas-dts-for-v6.14.
>>
>> Apparently this patch breaks s2idle on Gray Hawk Single when "[PATCH
>> v3 06/10] drm/rcar-du: dsi: Add r8a779h0 support" is not present, or
>> when CONFIG_DRM_RCAR_USE_MIPI_DSI is not enabled. If the DSI driver
>> is not available, the ti_sn65dsi86.bridge part fails to probe with
>> -EPROBE_DEFER and "failed to attach dsi host".  Still, the sn65dsi86
>> driver must do something critical, as resuming from s2idle now hangs.
>> I haven't identified yet where exactly it hangs.
>> > As a result, s2idle is broken in current renesas-devel, which only
>> has the DTS changes.  Perhaps I should drop the DTS until the issue
>> is resolved?
> 
> I'm fine with that. The DT bindings are still under work anyway.
> 
>> However, I suspect White Hawk has the same issue (if
>> CONFIG_DRM_RCAR_USE_MIPI_DSI=n), but I cannot verify as my local White
>> Hawk is currently not available for kernel testing.
> 
> I can reproduce on White Hawk. And I agree that it's probably related to 
> sn65dsi86.
> 
> I use modules, so I tried dropping modules to see when the issue goes 
> away. And it's always sn65dsi86. So without the rcar DRM & DSI modules 
> loaded, if I load or don't load sn65dsi86, I see or don't see the hang, 
> respectively.
> 
> Even if I drop the ti_sn65dsi86_pm_ops, it doesn't help. And looks like 
> just doing the i2c_add_driver() part in ti_sn65dsi86_init() will cause 
> the issue, so it's something that happens there.
> 
> I'll continue the debug later.

I wrote a minimal kernel module that has an i2c driver that does 
nothing, using ti,sn65dsi86 as the compatible string. I can still see 
the hang with that driver (i.e. no DRM drivers loaded at all). So it's 
not an issue in the driver.

I didn't really figure anything out, but I did notice that if I comment 
the following lines from the dts, the problem goes away:

		interrupt-parent = <&intc_ex>;
		interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;

		enable-gpios = <&gpio1 26 GPIO_ACTIVE_HIGH>;

		vccio-supply = <&reg_1p8v>;
		vpll-supply = <&reg_1p8v>;
		vcca-supply = <&reg_1p2v>;
		vcc-supply = <&reg_1p2v>;

  Tomi