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Date:   Mon, 30 Jan 2023 18:11:24 +0100
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Robert Marko" <robimarko@gmail.com>,
        "Andy Gross" <agross@kernel.org>,
        "Bjorn Andersson" <andersson@kernel.org>,
        "Konrad Dybcio" <konrad.dybcio@linaro.org>, bhelgaas@google.com,
        lpieralisi@kernel.org, "Rob Herring" <robh@kernel.org>,
        =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= <kw@linux.com>,
        krzysztof.kozlowski+dt@linaro.org,
        "Manivannan Sadhasivam" <mani@kernel.org>, svarbanov@mm-sol.com,
        shawn.guo@linaro.org, linux-arm-msm@vger.kernel.org,
        linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, "Abel Vesa" <abelvesa@kernel.org>
Subject: Re: [PATCH v2 8/9] arm64: dts: qcom: ipq8074: fix Gen3 PCIe node
Content-Type: text/plain
Precedence: bulk

On Fri, Jan 13, 2023, at 17:44, Robert Marko wrote:
> IPQ8074 comes in 2 silicon versions:
> * v1 with 2x Gen2 PCIe ports and QMP PHY-s
> * v2 with 1x Gen3 and 1x Gen2 PCIe ports and QMP PHY-s
>
> v2 is the final and production version that is actually supported by the
> kernel, however it looks like PCIe related nodes were added for the v1 SoC.
>
> Finish the PCIe fixup by using the correct compatible, adding missing ATU
> register space, declaring max-link-speed, use correct ranges, add missing
> clocks and resets.
>
> Fixes: 33057e1672fe ("ARM: dts: ipq8074: Add pcie nodes")
> Signed-off-by: Robert Marko <robimarko@gmail.com>

I was reading through the pull request today and saw this patch
along with the Gen2 one:


> @@ -871,9 +873,9 @@ pcie0: pci@20000000 {
>  			phy-names = "pciephy";
> 
>  			ranges = <0x81000000 0 0x20200000 0x20200000
> -				  0 0x100000   /* downstream I/O */
> +				  0 0x10000>, /* downstream I/O */

Fixing the length here seems fine, but the bus-side address
still looks wrong: 0x20200000 is way outside of the usual
port ranges from 0 to 0x10000 on the local bus.

> -				  0x82000000 0 0x20300000 0x20300000
> -				  0 0xd00000>; /* non-prefetchable memory */
> +				 <0x82000000 0 0x20220000 0x20220000
> +				  0 0xfde0000>; /* non-prefetchable memory */

I see the total size of the memory space is under 256MB. Are you
sure that there is no 64-bit BAR in addition to this?

I also see commit 7d1158c984d3 ("arm64: dts: qcom: sm8550: Add
PCIe PHYs and controllers nodes") introduce the same broken
I/O port range (oversized 1MB space wiht an identity map) for a
new SoC. This should probably be fixed as well, along with
reviewing the other ones.

Has the I/O space mapping on any of these actually been tested,
or just copied from one SoC to another? Very few devices actually
use I/O space, so it wouldn't be surprising if it never worked
in the first place.

       Arnd