Re: [PATCH] arm64: dts: ti: k3-j784s4-evm: Use 4 lanes for PCIe0 on EVM

[Siddharth Vadapalli <s-vadapalli@ti.com>]

On Wed, Aug 07, 2024 at 08:28:47AM -0500, Nishanth Menon wrote:
> On 16:34-20240720, Siddharth Vadapalli wrote:
> > The PCIe0 instance of the PCIe controller on J784S4 SoC supports up to 4
> > lanes. Additionally, all 4 lanes of PCIe0 can be utilized on J784S4-EVM
> > via SERDES1. Since SERDES1 is not being used by any peripheral apart
> > from PCIe0, use all 4 lanes of SERDES1 for PCIe0.
> > 
> > Fixes: 27ce26fe52d4 ("arm64: dts: ti: k3-j784s4-evm: Enable PCIe0 and PCIe1 in RC Mode")
> > Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>

[...]

> >  	serdes1_pcie0_link: phy@0 {
> >  		reg = <0>;
> > -		cdns,num-lanes = <2>;
> > +		cdns,num-lanes = <4>;
> >  		#phy-cells = <0>;
> >  		cdns,phy-type = <PHY_TYPE_PCIE>;
> > -		resets = <&serdes_wiz1 1>, <&serdes_wiz1 2>;
> > +		resets = <&serdes_wiz1 1>, <&serdes_wiz1 2>,
> > +			 <&serdes_wiz1 3>, <&serdes_wiz1 4>;
> >  	};
> 
> OK - I see the reason why
> https://lore.kernel.org/all/20240807132054.jcz5fdokc5yk3mbo@entrust/
> was missed.
> 
> Please sync with Manorit to make sure we sequence these correctly -
> looks to me that this fixup needs to get in first? have you also checked
> up on AM69-SK ?

J784S4 SoC has 4 instances of PCIe -> PCIe0, PCIe1, PCIe2 and PCIe3.
All 4 instances have been described in k3-j784s4-main.dtsi.
Of the 4 instances PCIe0 and PCIe1 are brought out on J784S4-EVM.
Therefore, k3-j784s4-evm.dts enables only PCIe0 and PCIe1.

This patch allocates all 4 lanes of SERDES1 to PCIe0 on J784S4-EVM since
no other peripheral is sharing SERDES1 with PCIe0.

On AM69-SK, all 4 lanes of SERDES1 have correctly been assigned to
PCIe0, due to which no fix is required.

J742S2 SoC has 2 instances of PCIe -> PCIe0 and PCIe1. They have the
same connections w.r.t. SERDES as J784S4 SoC i.e.
PCIe0 -> 4 Lanes of SERDES1
PCIe1 -> 2 Lanes of SERDES0

So PCIe2 and PCIe3 have to be removed from
k3-j784s4-j742s2-main-common.dtsi
in the patch by Manorit at:
https://lore.kernel.org/r/20240731-b4-upstream-j742s2-v3-4-da7fe3aa9e90@ti.com/
and added in k3-j784s4-main.dtsi similar to the "c71_3: dsp@67800000" node.

The changes made by this patch (assigning all 4 lanes of SERDES1 to PCIe0)
will be applicable to J742S2-EVM as well.

Regards,
Siddharth.