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s=mail20150812; t=1767637307; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MMJqVJMgue288REwsy/Kw6YGKx1SN8vSeF+6ZE5Moss=; b=D+zS7y9cPJmp7H19AB12Uc+mBc/ke2p2UuL4YS/0DSDQ4r9a1VtgyxCG3UMOVgOgehUf28 SC4w4+OQxJagppCvCwXk+2ay5KJdqaSkokOqIBSHotCxFb+laTaFAOTXUu+SUOb0qdzUpx 90yJkRxTdCmw/FuXWXIvMjkpNt9hStakeolIv+f+MkFrZ5totTC/Hz5wE7C2KnS/muevNw JGDj1ZmrNZ624ofZCrxpHgjcEFfrYWxZ95rKILE13KfaVyvWGpLFhdZUIyC5ETUGfs0gNE cnatCGqwGVkFCuTb+0jXZKCoKWSRE9CpChJ9ILyUnJlATxGRAS7CFiN2y34LYw== Message-ID: <0355f521-e506-447f-bc6a-cf4405903cfd@mailbox.org> Date: Mon, 5 Jan 2026 17:31:55 +0100 Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] arm64: dts: imx95: remove CLK_GPUAPB To: Rain Yang Cc: Frank.Li@nxp.com, conor+dt@kernel.org, devicetree@vger.kernel.org, festevam@gmail.com, imx@lists.linux.dev, jiyu.yang@nxp.com, kernel@pengutronix.de, krzk+dt@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, liviu.dudau@arm.com, robh@kernel.org, s.hauer@pengutronix.de, shawnguo@kernel.org References: <20251231031915.752262-1-jiyu.yang@oss.nxp.com> <37489cb7-820d-46cd-a7ea-0f9097604895@mailbox.org> <0de33175-1dc3-417b-8dab-9b57940f0789@mailbox.org> Content-Language: en-US From: Marek Vasut In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-MBO-RS-META: xdypdcre8setbt9xhn7hd96tdehyypri X-MBO-RS-ID: f32776500066e9b0833 On 1/5/26 3:19 AM, Rain Yang wrote: > On Fri, Jan 02, 2026 at 02:53:31PM +0100, Marek Vasut wrote: >> On 1/2/26 11:37 AM, Rain Yang wrote: >>> On Thu, Jan 01, 2026 at 05:51:12PM +0100, Marek Vasut wrote: >>>> On 1/1/26 1:37 AM, Rain Yang wrote: >>>>> On Wed, Dec 31, 2025 at 03:11:21PM +0100, Marek Vasut wrote: >>>>>> On 12/31/25 4:19 AM, Rain Yang wrote: >>>>>>> From: Rain Yang >>>>>>> >>>>>>> Dropping CLK_GPUAPB simplifies OPP handling and avoids unnecessary >>>>>>> complexity. >>>>>>> >>>>>>> Fixes: 67934f248e64 ("arm64: dts: imx95: Describe Mali G310 GPU") >>>>>>> Signed-off-by: Rain Yang >>>>>>> --- >>>>>>> arch/arm64/boot/dts/freescale/imx95.dtsi | 4 ++-- >>>>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>>>> >>>>>>> diff --git a/arch/arm64/boot/dts/freescale/imx95.dtsi b/arch/arm64/boot/dts/freescale/imx95.dtsi >>>>>>> index 88bde59e61b2..ab446aa6f73c 100644 >>>>>>> --- a/arch/arm64/boot/dts/freescale/imx95.dtsi >>>>>>> +++ b/arch/arm64/boot/dts/freescale/imx95.dtsi >>>>>>> @@ -2164,8 +2164,8 @@ netc_emdio: mdio@0,0 { >>>>>>> gpu: gpu@4d900000 { >>>>>>> compatible = "nxp,imx95-mali", "arm,mali-valhall-csf"; >>>>>>> reg = <0 0x4d900000 0 0x480000>; >>>>>>> - clocks = <&scmi_clk IMX95_CLK_GPU_CGC>, <&scmi_clk IMX95_CLK_GPUAPB>; >>>>>>> - clock-names = "core", "coregroup"; >>>>>>> + clocks = <&scmi_clk IMX95_CLK_GPU_CGC>; >>>>>>> + clock-names = "core"; >>>>>> >>>>>> I don't think this is correct, SM can disable the GPUAPB clock from the SM >>>>>> monitor: >>>>>> >>>>>>> $ clock.w gpuapb off >>>>>> >>>>>> Linux has to make sure the GPUAPB clock are enabled to access the GPU >>>>>> register, hence the clock have to be described in DT. >>>>> Hi Marek, >>>> >>>> Hello Jiyu, >>>> >>>>> CLK_GPU and CLK_GPUAPB can only be controlled internally by the SM, not by Linux. >>>>> CLK_GPUAPB always runs at a fixed frequency, does not require dynamic adjustment, >>>>> and is practically always on. >>>>> Additionally, CLK_GPUAPB's frequency is absent from all OPP entries. Removing it >>>>> could simplify OPP handling logic and reduce unnecessary complexity. >>>> >>>> But the SM can turn the GPUAPB clock off, correct ? >>>> >>>> Linux has to be able to turn GPUAPB clock on, therefore the GPUAPB clock have >>>> to be described in DT, correct ? >>> >>> Yes, CLK_GPUAPB can be turned off by the SM, but by default it remains on, just like >>> CLK_GPU. AFAIK, there is no scenario where either of these clocks could or would be >>> disabled in both SM and Linux. >>> >>> If enabling or disabling CLK_GPUAPB in Linux was wanted, the same shall apply to CLK_GPU >>> to make this approach reasonable. >>> Also, OPP framework shall be adjusted to meet these changes too. >> >> You can not depend on the state in which bootloader or any other prior stage >> left the platform. If the clock can be turned off, you must make sure they >> are turned on for correct hardware operation. >> >> CLK_GPU is enabled as parent clock of CLK_GPUCGC already. > Hi Marek, > I'm afraid it's not what you expected, the CLK_GPUCGC patch already based on the CLK_GPU is > always-on, you can disable the CLK_GPU in SM, then run any gles application, the board will reboot. Which kernel version are you testing ? Also, can you share your /sys/kernel/debug/clk/clk_summary ? The clock relationship should be visible there.