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From: John Watts <contact@jookia.org>
To: Paul Cercueil <paul@crapouillou.net>
Cc: Jessica Zhang <quic_jesszhan@quicinc.com>,
	dri-devel@lists.freedesktop.org,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Sam Ravnborg <sam@ravnborg.org>, David Airlie <airlied@gmail.com>,
	Daniel Vetter <daniel@ffwll.ch>, Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Shawn Guo <shawnguo@kernel.org>, Heiko Stuebner <heiko@sntech.de>,
	Chris Morgan <macromorgan@hotmail.com>,
	Jagan Teki <jagan@edgeble.ai>,
	Christophe Branchereau <cbranchereau@gmail.com>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 3/9] drm/panel: nv3052c: Sleep for 150ms after reset
Date: Tue, 19 Sep 2023 07:40:58 +1000	[thread overview]
Message-ID: <ZQjD6gCEo62gMBX2@titan> (raw)
In-Reply-To: <0d6b0159552b10548391a9bd88449d12c13fdcd6.camel@crapouillou.net>

On Mon, Sep 18, 2023 at 11:34:51PM +0200, Paul Cercueil wrote:
> The driver is guaranteed to always reset the panel in sleep-in mode -
> as long as the panel was off when the driver started.
> 
> What I'd suggest if you really need to support a case where the panel
> was enabled by the bootloader, is to read the 0x0a register after
> enabling the regulator to read the mode, and sleep 120ms if it was in
> sleep-out mode.
> 
> But that's only if it's a case that you can test with. I won't accept a
> patch that makes sense on the surface if it addresses a corner case
> that nobody ever tested for.
> 
> For what I know, this patch just adds a huge delay to panel boot-up for
> all existing users for no valid reason.
>
> 
> Cheers,
> -Paul

Thank you very much for this feedback. I am more than happy to throw these
sleep patches in the trash and come back later with a proper solution when
I have an actual hardware setup and use case to test on.

John.

  reply	other threads:[~2023-09-18 21:41 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-18 12:58 [RFC PATCH v2 0/9] Add FS035VG158 panel John Watts
2023-09-18 12:58 ` [RFC PATCH v2 1/9] drm/panel: nv3052c: Document known register names John Watts
2023-09-18 12:58 ` [RFC PATCH v2 2/9] drm/panel: nv3052c: Add SPI device IDs John Watts
2023-09-18 12:58 ` [RFC PATCH v2 3/9] drm/panel: nv3052c: Sleep for 150ms after reset John Watts
2023-09-18 20:19   ` Jessica Zhang
2023-09-18 20:52     ` John Watts
2023-09-18 21:01       ` Paul Cercueil
2023-09-18 21:08         ` John Watts
2023-09-18 21:34           ` Paul Cercueil
2023-09-18 21:40             ` John Watts [this message]
2023-09-18 12:58 ` [RFC PATCH v2 4/9] drm/panel: nv3052c: Wait before entering sleep mode John Watts
2023-09-18 20:27   ` Jessica Zhang
2023-09-18 12:58 ` [RFC PATCH v2 5/9] drm/panel: nv3052c: Allow specifying registers per panel John Watts
2023-09-18 12:58 ` [RFC PATCH v2 6/9] drm/panel: nv3052c: Add Fascontek FS035VG158 LCD display John Watts
2023-09-18 20:35   ` Jessica Zhang
2023-09-18 12:58 ` [RFC PATCH v2 7/9] dt-bindings: display: panel: Clean up leadtek,ltk035c5444t properties John Watts
2023-09-18 22:28   ` Rob Herring
2023-09-18 12:58 ` [RFC PATCH v2 8/9] dt-bindings: vendor-prefixes: Add fascontek John Watts
2023-09-18 12:58 ` [RFC PATCH v2 9/9] dt-bindings: display: panel: add Fascontek FS035VG158 panel John Watts
2023-09-18 22:29   ` Rob Herring

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