From: Christoph Hellwig <hch@lst.de>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Sven Schnelle <svens@stackframe.org>,
Christoph Hellwig <hch@lst.de>, 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 23:25:54 +0200 [thread overview]
Message-ID: <20190924212554.GA31357@lst.de> (raw)
In-Reply-To: <1569286782.3657.29.camel@HansenPartnership.com>
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.
Svens patch looks right for how we are now using the DMA mask setting
API.
next prev parent reply other threads:[~2019-09-24 21:26 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 [this message]
2019-09-24 21:59 ` James Bottomley
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