linux-kernel - Re: [PATCH v2 0/7] Add DSI support for RK3128

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Message-ID: <38423821.XM6RcZxFsP@diego>
Date: Thu, 09 May 2024 14:21:47 +0200
From: Heiko Stübner <heiko@...ech.de>
To: Sandy Huang <hjc@...k-chips.com>, Andy Yan <andy.yan@...k-chips.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>,
 Alex Bee <knaerzche@...il.com>
Cc: dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
 Alex Bee <knaerzche@...il.com>, sebastian.reichel@...labora.com
Subject: Re: [PATCH v2 0/7] Add DSI support for RK3128

Hi Alex,

Am Donnerstag, 9. Mai 2024, 14:07:08 CEST schrieb Alex Bee:
> This series aims to add support for the DesignWare MIPI DSI controller and
> the Innoslicon D-PHY found in RK3128 SoCs. The code additions are rather
> tiny: It only need some code in the Rockchip dw-mipi-dsi glue layer for
> this SoC, add support for an additional clock and do some changes in the
> SoC's clock driver. Support for the phy was already added when the
> Innosilicon D-PHY driver was initially submitted. I tested it with a
> 800x1280 DSI panel where all 4 lanes that are supported are used.
> 
> changes in v2:
>   To improve power-efficiency when the DSI controller is not in use, I
>   dropped the patch which made hclk_vio_h2p a critical clock and instead
>   added support for an AHB clock to the DSI controller driver and updated
>   the bindings and the addition to the SoC DT accordingly.

The naming already suggests that hclk_vio_h2p is not a clock-part of
the actual dsi controller, but more an internal thing inside the clock
controller.

At least naming and perceived functionality would suggest a chain of
	hclk_vio -> hclk_vio_h2p -> pclk_mipi

In any case, I really don't see hclk_vio_h2p to be in the realm of the
actual DSI controller, but more a part of clock-controller / interconnect.
Similar to the NIU clocks for the interconnect.

rk3588 actually tries to implement this already and while the
gate-link clocks are described as "recent", I think this definitly the same
concept used a most/all older Rockchip SoCs, just nobody cared about that
till now ;-) [0] .

So TL;DR I'd really prefer to not leak CRU-details into the DSI controller.


Heiko

[0] Which reminds me that I should look at Sebastian's make GATE-LINK
actually-work-patch.