From: Russell Currey <ruscur@russell.cc>
To: Alistair Popple <alistair@popple.id.au>,
benh@kernel.crashing.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/powernv/pci: Return failure for some uses of dma_set_mask()
Date: Fri, 28 Jul 2017 10:54:17 +1000 [thread overview]
Message-ID: <1501203257.4721.1.camel@russell.cc> (raw)
In-Reply-To: <1501046800-6690-1-git-send-email-alistair@popple.id.au>
On Wed, 2017-07-26 at 15:26 +1000, Alistair Popple wrote:
> Commit 8e3f1b1d8255 ("powerpc/powernv/pci: Enable 64-bit devices to access
> > 4GB DMA space") introduced the ability for PCI device drivers to request a
>
> DMA mask between 64 and 32 bits and actually get a mask greater than
> 32-bits. However currently if certain machine configuration dependent
> conditions are not meet the code silently falls back to a 32-bit mask.
>
> This makes it hard for device drivers to detect which mask they actually
> got. Instead we should return an error when the request could not be
> fulfilled which allows drivers to either fallback or implement other
> workarounds as documented in DMA-API-HOWTO.txt.
>
> Signed-off-by: Alistair Popple <alistair@popple.id.au>
Acked-by: Russell Currey <ruscur@russell.cc>
next prev parent reply other threads:[~2017-07-28 0:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-26 5:26 [PATCH] powerpc/powernv/pci: Return failure for some uses of dma_set_mask() Alistair Popple
2017-07-28 0:54 ` Russell Currey [this message]
2017-07-31 6:31 ` Michael Ellerman
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