linux-kernel - Re: [PATCH v2] rockchip/drm: vop2: make vp registers nonvolatile

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Message-ID: <175516475520.1500001.17369279178987813949.b4-ty@sntech.de>
Date: Thu, 14 Aug 2025 11:46:06 +0200
From: Heiko Stuebner <heiko@...ech.de>
To: hjc@...k-chips.com,
	andy.yan@...k-chips.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Piotr Zalewski <pZ010001011111@...ton.me>
Cc: Heiko Stuebner <heiko@...ech.de>,
	Diederik de Haas <didi.debian@...ow.org>
Subject: Re: [PATCH v2] rockchip/drm: vop2: make vp registers nonvolatile


On Sun, 06 Jul 2025 08:36:58 +0000, Piotr Zalewski wrote:
> Make video port registers nonvolatile. As DSP_CTRL register is written
> to twice due to gamma LUT enable bit which is set outside of the main
> DSP_CTRL initialization within atomic_enable (for rk356x case it is also
> necesarry to always disable gamma LUT before writing a new LUT) there is
> a chance that DSP_CTRL value read-out in gamma LUT init/update code is
> not the one which was written by the preceding DSP_CTRL initialization
> code within atomic_enable. This might result in misconfigured DSP_CTRL
> which leads to no visual output[1]. Since DSP_CTRL write takes effect
> after VSYNC[1] the issue is not always present. When tested on Pinetab2
> with kernel 6.14 it happenes only when DRM is compiled as a module[1].
> In order to confirm that it is a timing issue I inserted 18ms udelay
> before vop2_crtc_atomic_try_set_gamma in atomic enable and compiled DRM
> as module - this has also fixed the issue.
> 
> [...]

Applied, thanks!

[1/1] rockchip/drm: vop2: make vp registers nonvolatile
      commit: a52dffaa46c2c5ff0b311c4dc1288581f7b9109e

Best regards,
-- 
Heiko Stuebner <heiko@...ech.de>