Re: [v4 10/11] riscv: dts: fu740: Add pmu node
From: Jessica Clarke <hidden>
Date: 2021-10-28 20:49:07
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linux-devicetree, linux-perf-users, linux-riscv, lkml
On Mon, Oct 25, 2021 at 12:53:49PM -0700, Atish Patra wrote:
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HiFive unmatched supports HPMCounters but does not implement mcountinhibit or sscof extension. Thus, perf monitoring can be used on the unmatched board without sampling. Add the PMU node with compatible string so that Linux perf driver can utilize this to enable PMU. Signed-off-by: Atish Patra <redacted> --- arch/riscv/boot/dts/sifive/fu740-c000.dtsi | 3 +++ 1 file changed, 3 insertions(+)diff --git a/arch/riscv/boot/dts/sifive/fu740-c000.dtsi b/arch/riscv/boot/dts/sifive/fu740-c000.dtsi index abbb960f90a0..b35b96b58820 100644 --- a/arch/riscv/boot/dts/sifive/fu740-c000.dtsi +++ b/arch/riscv/boot/dts/sifive/fu740-c000.dtsi@@ -140,6 +140,9 @@ soc { #size-cells = <2>; compatible = "simple-bus"; ranges; + pmu { + compatible = "riscv,pmu"; + };
This is a property of the user-replaceable firmware, not a property of the hardware, so having this in the device tree under /soc, let alone hard-coded in Linux, is utterly wrong. Why can this not just be probed like any other SBI interface? The "Probe SBI extension" interface is precisely for this kind of thing. Jess