From: Christoph Hellwig <hch@lst.de>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Robin Murphy <robin.murphy@arm.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 1/2] dma-mapping: add a dma_ops_bypass flag to struct device
Date: Mon, 23 Mar 2020 09:50:59 +0100 [thread overview]
Message-ID: <20200323085059.GA32528@lst.de> (raw)
In-Reply-To: <20200323083705.GA31245@lst.de>
On Mon, Mar 23, 2020 at 09:37:05AM +0100, Christoph Hellwig wrote:
> > > + /*
> > > + * Allows IOMMU drivers to bypass dynamic translations if the DMA mask
> > > + * is large enough.
> > > + */
> > > + if (dev->dma_ops_bypass) {
> > > + if (min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit) >=
> > > + dma_direct_get_required_mask(dev))
> > > + return true;
> > > + }
> >
> >
> > Why not do this in dma_map_direct() as well?
>
> Mostly beacuse it is a relatively expensive operation, including a
> fls64.
Which I guess isn't too bad compared to a dynamic IOMMU mapping. Can
you just send a draft patch for what you'd like to see for ppc?
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next prev parent reply other threads:[~2020-03-23 8:51 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 14:16 generic DMA bypass flag v2 Christoph Hellwig
2020-03-20 14:16 ` [PATCH 1/2] dma-mapping: add a dma_ops_bypass flag to struct device Christoph Hellwig
2020-03-20 15:02 ` Greg Kroah-Hartman
2020-03-23 1:28 ` Alexey Kardashevskiy
2020-03-23 8:37 ` Christoph Hellwig
2020-03-23 8:50 ` Christoph Hellwig [this message]
2020-03-23 15:37 ` Aneesh Kumar K.V
2020-03-23 17:22 ` Christoph Hellwig
2020-03-24 3:05 ` Alexey Kardashevskiy
2020-03-24 6:30 ` Aneesh Kumar K.V
2020-03-24 7:55 ` Christoph Hellwig
2020-03-24 7:54 ` Christoph Hellwig
2020-03-25 4:51 ` Alexey Kardashevskiy
2020-03-25 8:37 ` Christoph Hellwig
2020-03-26 1:26 ` Alexey Kardashevskiy
2020-04-03 8:38 ` Alexey Kardashevskiy
2020-04-06 11:50 ` Christoph Hellwig
2020-04-06 13:25 ` Alexey Kardashevskiy
2020-04-06 17:17 ` Christoph Hellwig
2020-04-07 10:12 ` Alexey Kardashevskiy
2020-04-14 6:21 ` Alexey Kardashevskiy
2020-04-14 6:30 ` Christoph Hellwig
2020-03-23 8:58 ` Alexey Kardashevskiy
2020-03-23 17:20 ` Christoph Hellwig
2020-03-24 3:37 ` Alexey Kardashevskiy
2020-03-24 4:55 ` Alexey Kardashevskiy
2020-03-24 7:52 ` Christoph Hellwig
2020-03-23 12:14 ` Robin Murphy
2020-03-23 12:55 ` Christoph Hellwig
2020-03-20 14:16 ` [PATCH 2/2] powerpc: use the generic dma_ops_bypass mode Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2019-11-13 13:37 generic DMA bypass flag Christoph Hellwig
2019-11-13 13:37 ` [PATCH 1/2] dma-mapping: add a dma_ops_bypass flag to struct device Christoph Hellwig
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