From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Sven Schnelle <svens@stackframe.org>,
Helge Deller <deller@gmx.de>,
linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: allow larger than require DMA masks
Date: Tue, 24 Sep 2019 17:59:28 -0400 [thread overview]
Message-ID: <1569362368.5364.19.camel@HansenPartnership.com> (raw)
In-Reply-To: <20190924212554.GA31357@lst.de>
On Tue, 2019-09-24 at 23:25 +0200, Christoph Hellwig wrote:
> On Mon, Sep 23, 2019 at 08:59:42PM -0400, James Bottomley wrote:
> > > if (mask > ~0U)
> > > » » return 0;
> > >
> > > Removing the if() makes the DMA mapping work. It's almost
> > > midnight here, so i won't look into that any further today. Does
> > > anyone have an opinion on this behaviour? Otherwise i will look a
> > > bit more into this in the next days.
> >
> > The reason for the if was to kick the device into 32 bit
> > descriptors, which are usually more efficient, especially with
> > older dual descriptor format cards like we have on parisc systems.
>
> These days we use the dma_get_required_mask API to query for that.
It looks like sym53c8xx didn't get the memo. On the other hand, I'm
fairly certain it should be compiled in addressing mode zero on all
parisc systems (since all the 64 bit ones have iommus), so I think we
can take care of this ourselves.
> Svens patch looks right for how we are now using the DMA mask setting
> API.
Agreed.
James
prev parent reply other threads:[~2019-09-24 21:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-15 14:45 allow larger than require DMA masks Christoph Hellwig
2019-02-15 14:45 ` [PATCH 1/5] ccio: allow large " Christoph Hellwig
2019-02-15 14:45 ` [PATCH 2/5] sparc64: refactor the ali DMA quirk Christoph Hellwig
2019-02-15 18:34 ` David Miller
2019-02-15 14:45 ` [PATCH 3/5] sparc64/iommu: allow large DMA masks Christoph Hellwig
2019-02-15 18:34 ` David Miller
2019-02-15 14:45 ` [PATCH 4/5] sparc64/pci_sun4v: " Christoph Hellwig
2019-02-15 18:35 ` David Miller
2019-02-15 14:45 ` [PATCH 5/5] Documentation/DMA-API-HOWTO: update dma_mask sections Christoph Hellwig
2019-02-18 1:26 ` Yang, Shunyong
2019-09-23 21:14 ` allow larger than require DMA masks Sven Schnelle
2019-09-24 0:59 ` James Bottomley
2019-09-24 21:25 ` Christoph Hellwig
2019-09-24 21:59 ` James Bottomley [this message]
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