Re: [PATCH] arm64: dts: ti: k3-j721e-beagleboneai64: Enable ACSPCIE output for PCIe1

[Krzysztof Kozlowski <krzk@kernel.org>]

On 27/11/2024 10:17, Romain Naour wrote:
> Hello,
> 
> Le 26/11/2024 à 20:04, Krzysztof Kozlowski a écrit :
>> On 26/11/2024 18:33, Romain Naour wrote:
>>> From: Romain Naour <romain.naour@skf.com>
>>>
>>> Unlike the SK-TDA4VM (k3-j721e-sk) board, there is no clock generator
>>> (CDCI6214RGET) on the BeagleBone AI-64 (k3-j721e-beagleboneai64) to
>>> provide PCIe refclk signal to PCIe Endponts. So the ACSPCIE module must
>>> provide refclk through PCIe_REFCLK pins.
>>>
>>> Use the new "ti,syscon-acspcie-proxy-ctrl" property to enable ACSPCIE
>>> module's PAD IO Buffers.
>>>
>>> Signed-off-by: Romain Naour <romain.naour@skf.com>
>>> ---
>>> With this patch, we can remove "HACK: Sierra: Drive clock out" patch
>>> applied on vendor kernel for BeagleBone AI-64:
>>> https://openbeagle.org/beagleboard/linux/-/commit/ad65d7ef675966cdbc5d75f2bd545fad1914ba9b
>>> ---
>>>  arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts |  4 ++++
>>>  arch/arm64/boot/dts/ti/k3-j721e-main.dtsi          | 10 ++++++++--
>>>  2 files changed, 12 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts b/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts
>>> index fb899c99753e..681e3af7ce6e 100644
>>> --- a/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts
>>> +++ b/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts
>>> @@ -859,6 +859,10 @@ &pcie1_rc {
>>>  	num-lanes = <2>;
>>>  	max-link-speed = <3>;
>>>  	reset-gpios = <&main_gpio0 22 GPIO_ACTIVE_HIGH>;
>>> +	/* There is no on-board or external reference clock generators,
>>
>> Please use generic style comments, not netdev.
> 
> Fixed.
> 
>>
>>> +	 * use refclk from the ACSPCIE module's PAD IO Buffers.
>>> +	 */
>>> +	ti,syscon-acspcie-proxy-ctrl = <&acspcie0_proxy_ctrl 0x3>;
>>>  };
>>>  
>>>  &ufs_wrapper {
>>> diff --git a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
>>> index 0da785be80ff..9f47e7672922 100644
>>> --- a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
>>> +++ b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
>>> @@ -5,6 +5,7 @@
>>>   * Copyright (C) 2016-2024 Texas Instruments Incorporated - https://www.ti.com/
>>>   */
>>>  #include <dt-bindings/phy/phy.h>
>>> +#include <dt-bindings/phy/phy-cadence.h>
>>>  #include <dt-bindings/phy/phy-ti.h>
>>>  #include <dt-bindings/mux/mux.h>
>>>  
>>> @@ -82,6 +83,11 @@ ehrpwm_tbclk: clock-controller@4140 {
>>>  			reg = <0x4140 0x18>;
>>>  			#clock-cells = <1>;
>>>  		};
>>> +
>>> +		acspcie0_proxy_ctrl: acspcie0-ctrl@18090 {
>>
>> Node names should be generic. See also an explanation and list of
>> examples (not exhaustive) in DT specification:
>> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
> 
> I updated to: "acspcie0_proxy_ctrl: acspcie-ctrl@18090"

Not much changed. It's a system-controller?

> 
>>
>>
>>> +			compatible = "ti,j784s4-acspcie-proxy-ctrl", "syscon";
>>
>> I am not familiar with naming, so is this j784s4 or j721e or K3 SoC?
>> Compatible should be SoC specific.
> 
> Me neither.

Hm? So it is like a random change?

> 
> "ti,j784s4-acspcie-proxy-ctrl" compatible is the only one available in the
> syscon devicetree binding. Should we add a new "ti,j721e-acspcie-proxy-ctrl"?

When you add new devices, add bindings.

> 
> This patch is adapted from a recent commit on the TI's kernel for the j784s4 Soc:
> https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/?h=ti-rt-linux-6.6.y&id=bb4442cd523d6e34c5db43fd78c9f579d6937f6a

Sorry, v6.6 downstream code is totally irrelevant for this. They can
introduce bugs or wrong code and this is never a reason to repeat the
same in mainline.

> 
> There is another example with "ti,j784s4-pcie-ctrl" compatible used from
> k3-j722s-main.dtsi:
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm64/boot/dts/ti/k3-j722s-main.dtsi?h=v6.12.1#n240

Well, people repeat the same mistakes over and over.

Best regards,
Krzysztof