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From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>, linuxppc-dev@lists.ozlabs.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Subject: Re: [kernel] powerpc/powernv/ioda2: Reduce upper limit for DMA window size (retry)
Date: Fri, 21 Sep 2018 21:59:38 +1000 (AEST)	[thread overview]
Message-ID: <42GsbG2KQHz9sCV@ozlabs.org> (raw)
In-Reply-To: <20180911053805.5345-1-aik@ozlabs.ru>

On Tue, 2018-09-11 at 05:38:05 UTC, Alexey Kardashevskiy wrote:
> We use PHB in mode1 which uses bit 59 to select a correct DMA window.
> However there is mode2 which uses bits 59:55 and allows up to 32 DMA
> windows per a PE.
> 
> Even though documentation does not clearly specify that, it seems that
> the actual hardware does not support bits 59:55 even in mode1, in other
> words we can create a window as big as 1<<58 but DMA simply won't work.
> 
> This reduces the upper limit from 59 to 55 bits to let the userspace know
> about the hardware limits.
> 
> Fixes: ce57c6610cc2 "Merge branch 'topic/ppc-kvm' into next"
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/7233b8cab39014620ac9534da11f0f

cheers

      reply	other threads:[~2018-09-21 11:59 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-11  5:38 [PATCH kernel] powerpc/powernv/ioda2: Reduce upper limit for DMA window size (retry) Alexey Kardashevskiy
2018-09-21 11:59 ` Michael Ellerman [this message]

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