linux-kernel - Re: [RFC 2/3] RISC-V:Support per-hart timebase-frequency

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Message-ID: <mhng-54e4fe3d-12d8-48c7-b1ea-df317fb3ff3a@palmer-si-x1c4>
Date:   Fri, 28 Sep 2018 17:20:45 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...ive.com>
To:     Christoph Hellwig <hch@...radead.org>
CC:     atish.patra@....com, linux-riscv@...ts.infradead.org,
        Christoph Hellwig <hch@...radead.org>, mark.rutland@....com,
        robh@...nel.org, Damien.LeMoal@....com, marc.zyngier@....com,
        anup@...infault.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de
Subject:     Re: [RFC 2/3] RISC-V:Support per-hart timebase-frequency

On Mon, 17 Sep 2018 07:23:08 PDT (-0700), Christoph Hellwig wrote:
> On Fri, Sep 14, 2018 at 02:54:55PM -0700, Atish Patra wrote:
>> Follow the updated DT specs and read the timebase-frequency
>> from the boot cpu. Keep the old DT reading as well for backward
>> compatibility. This patch is rework of old patch from Palmer.
>>
>> Signed-off-by: Atish Patra <atish.patra@....com>
>
> This setup looks a bit odd because it keeps blindly overwriting
> riscv_timebase for every cpu found.  Shouldn't we at least check that
> they all match for now as the rest of the port assumes that?

I agree.  There should be at least a warning if they don't match, but ideally 
we'd just support per-CPU timebases.  We have those systems already, they just 
don't boot Linux (at least, not yet :)).