linux-kernel - Re: [PATCH] arm64: dts: rockchip: Assign RK3399 VDU clock rate

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Message-ID: <253e2771abb13a3e62c07dfb0b420169bb572c2d.camel@collabora.com>
Date:   Tue, 07 Jun 2022 17:20:41 -0400
From:   Nicolas Dufresne <nicolas.dufresne@...labora.com>
To:     Brian Norris <briannorris@...omium.org>,
        Heiko Stuebner <heiko@...ech.de>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Sebastian Fricke <sebastian.fricke@...labora.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
        stable@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: Assign RK3399 VDU clock rate

Le mardi 07 juin 2022 à 14:15 -0700, Brian Norris a écrit :
> Before commit 9998943f6dfc ("media: rkvdec: Stop overclocking the
> decoder"), the rkvdec driver was forcing the VDU clock rate. After that
> commit, we rely on the default clock rate. That rate works OK on many
> boards, with the default PLL settings (CPLL is 800MHz, VDU dividers
> leave it at 400MHz); but some boards change PLL settings.
> 
> Assign the expected default clock rate explicitly, so that the rate is
> consistent, regardless of PLL configuration.
> 
> This was particularly broken on RK3399 Gru Scarlet systems, where the
> rk3399-gru-scarlet.dtsi assigns PLL_CPLL to 1.6 GHz, and so the VDU
> clock ends up at 800 MHz (twice the expected rate), and causes video
> artifacts and other issues.
> 
> Note: I assign the clock rate in the clock controller instead of the
> vdec node, because there are multiple nodes that use this clock, and per
> the clock.yaml specification:
> 
>   Configuring a clock's parent and rate through the device node that
>   consumes the clock can be done only for clocks that have a single
>   user. Specifying conflicting parent or rate configuration in multiple
>   consumer nodes for a shared clock is forbidden.
> 
>   Configuration of common clocks, which affect multiple consumer devices
>   can be similarly specified in the clock provider node.
> 
> Fixes: 9998943f6dfc ("media: rkvdec: Stop overclocking the decoder")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Brian Norris <briannorris@...omium.org>

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>

My only doubt was if you really needed to duplicate that setting into gru-
scarlet.dtsi, but I've simply assumed the answer is yes, and that you already
checked that.

> ---
> This is a candidate for 5.19 IMO, since commit 9998943f6dfc landed in
> 5.19-rc1 and is being queued up for -stable as we speak.
> 
>  arch/arm64/boot/dts/rockchip/rk3399-gru-scarlet.dtsi | 4 +++-
>  arch/arm64/boot/dts/rockchip/rk3399.dtsi             | 6 ++++--
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399-gru-scarlet.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-gru-scarlet.dtsi
> index 913d845eb51a..1977103a5ef4 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399-gru-scarlet.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399-gru-scarlet.dtsi
> @@ -376,7 +376,8 @@ &cru {
>  		<&cru ACLK_VIO>,
>  		<&cru ACLK_GIC_PRE>,
>  		<&cru PCLK_DDR>,
> -		<&cru ACLK_HDCP>;
> +		<&cru ACLK_HDCP>,
> +		<&cru ACLK_VDU>;
>  	assigned-clock-rates =
>  		<600000000>, <1600000000>,
>  		<1000000000>,
> @@ -388,6 +389,7 @@ &cru {
>  		<400000000>,
>  		<200000000>,
>  		<200000000>,
> +		<400000000>,
>  		<400000000>;
>  };
>  
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> index fbd0346624e6..9d5b0e8c9cca 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> @@ -1462,7 +1462,8 @@ cru: clock-controller@...60000 {
>  			<&cru HCLK_PERILP1>, <&cru PCLK_PERILP1>,
>  			<&cru ACLK_VIO>, <&cru ACLK_HDCP>,
>  			<&cru ACLK_GIC_PRE>,
> -			<&cru PCLK_DDR>;
> +			<&cru PCLK_DDR>,
> +			<&cru ACLK_VDU>;
>  		assigned-clock-rates =
>  			 <594000000>,  <800000000>,
>  			<1000000000>,
> @@ -1473,7 +1474,8 @@ cru: clock-controller@...60000 {
>  			 <100000000>,   <50000000>,
>  			 <400000000>, <400000000>,
>  			 <200000000>,
> -			 <200000000>;
> +			 <200000000>,
> +			 <400000000>;
>  	};
>  
>  	grf: syscon@...70000 {