Message-ID: <555F776E.3070904@imgtec.com>
Date: Fri, 22 May 2015 11:37:34 -0700
From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
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To: Ralf Baechle <ralf@linux-mips.org>
CC: <linux-mips@linux-mips.org>, <rusty@rustcorp.com.au>,
        <alexinbeijing@gmail.com>, <paul.burton@imgtec.com>,
        <david.daney@cavium.com>, <alex@alex-smith.me.uk>,
        <linux-kernel@vger.kernel.org>, <james.hogan@imgtec.com>,
        <markos.chandras@imgtec.com>, <macro@linux-mips.org>,
        <eunb.song@samsung.com>, <manuel.lauss@gmail.com>,
        <andreas.herrmann@caviumnetworks.com>
Subject: Re: [PATCH 1/2] MIPS: MSA: bugfix - disable MSA during thread switch
 correctly
References: <20150519211222.35859.52798.stgit@ubuntu-yegoshin> <20150519211351.35859.80332.stgit@ubuntu-yegoshin> <20150522093812.GH6941@linux-mips.org>
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On 05/22/2015 02:38 AM, Ralf Baechle wrote:
> Just move the call to finish_arch_switch(). 

It might be a problem later, then a correct MSA partiton starts working. 
It should be tight to saving MSA registers in that case.

> Your rewrite also dropped the if (cpu_has_msa) condition from 
> disable_msa() probably causing havoc on lots of CPUs which will likely 
> not decode the set bits of the MFC0/MTC0 instructions thus end up 
> accessing Config0. Ralf

Right before this chunk of code there is a saving MSA registers. Does it 
causing a havoc or else?

May I ask you to look into switch_to macro to figure out how "if 
(cpu_has_msa)" check works in this case?

- Leonid.

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