PCIe support in APQ8098-based board

[marc.w.gonzalez@free.fr (Marc Gonzalez)]

On 12/11/2018 21:26, Niklas Cassel wrote:

> On Sun, Nov 11, 2018 at 11:26:29PM +0100, Marc Gonzalez wrote:
>> Hello,
> 
> Hello Marc
> 
>>
>> I'm playing with an APQ8098-based board, which I got to boot an upstream
>> v4.20-rc1 kernel to the command line, by reusing the msm8998-mtp.dts
>> (IIUC apq8098 is the msm8998's "little brother", in that they are
>> almost the same SoC, with some HW blocks missing in the apq8098).
> 
> That is correct.
> 
>>
>> I'm trying to get PCIe working on my eval board. I'm wondering if
>> someone from qcom, codeaurora, or linaro has perhaps already done
>> this work, and it's just not upstream yet?
> 
> Linaro will most likely look at this at some undefined time in the future.
> 
> Here are some hints in case you need this urgently:
> 
> msm8998 uses QCOM PCIe v2.3.3, which is supported by
> drivers/pci/controller/dwc/pcie-qcom.c
> 
> I suggest that you look at:
> arch/arm64/boot/dts/qcom/ipq8074.dtsi
> 
> However, note that the PCI ranges are different for this SoC compared to
> ipq8074.
> 
> The correct ranges can be found here:
> https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/arch/arm/boot/dts/qcom/msm8998.dtsi?h=msm-4.4#n2538
> 
> It also appears that drivers/clk/qcom/gcc-msm8998.c is missing some PCIe
> resets.
> The correct addresses for these clocks can be found here:
> https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/drivers/clk/msm/clock-gcc-8998.c?h=msm-4.4
> 
> Note that the qcom_pcie_get_resources_2_3_3() will have to be modified
> slightly for msm8998, since msm8998 only has 3 PCIe resets.

Hello Niklas,

Thanks for the pointers. Bjorn also suggested I look into ipq8074.dtsi

Regards.