From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Stewart Smith <stewart@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, benh@kernel.crashing.org
Cc: Stewart Smith <stewart@linux.ibm.com>
Subject: Re: hvc_opal: don't set tb_ticks_per_usec in udbg_init_opal_common()
Date: Tue, 5 Jun 2018 00:10:30 +1000 (AEST) [thread overview]
Message-ID: <40zxfb0Fltz9ryk@ozlabs.org> (raw)
In-Reply-To: <20180329060246.9970-1-stewart@linux.ibm.com>
On Thu, 2018-03-29 at 06:02:46 UTC, Stewart Smith wrote:
> time_init() will set up tb_ticks_per_usec based on reality.
> time_init() is called *after* udbg_init_opal_common() during boot.
>
> from arch/powerpc/kernel/time.c:
> unsigned long tb_ticks_per_usec = 100; /* sane default */
>
> Currently, all powernv systems have a timebase frequency of 512mhz
> (512000000/1000000 == 0x200) - although there's nothing written
> down anywhere that I can find saying that we couldn't make that
> different based on the requirements in the ISA.
>
> So, we've been (accidentally) thwacking the (currently) correct
> (for powernv at least) value for tb_ticks_per_usec earlier than
> we otherwise would have.
>
> The "sane default" seems to be adequate for our purposes between
> udbg_init_opal_common() and time_init() being called, and if it isn't,
> then we should probably be setting it somewhere that isn't hvc_opal.c!
>
> Signed-off-by: Stewart Smith <stewart@linux.ibm.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/447808bf500a7cc92173266a59f8a4
cheers
prev parent reply other threads:[~2018-06-04 14:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-29 6:02 [PATCH] hvc_opal: don't set tb_ticks_per_usec in udbg_init_opal_common() Stewart Smith
2018-06-04 14:10 ` Michael Ellerman [this message]
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