From: Joerg Roedel <joro@8bytes.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Robin Murphy <robin.murphy@arm.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 3/4] dma-mapping: add a dma_ops_bypass flag to struct device
Date: Sat, 18 Apr 2020 14:42:05 +0200 [thread overview]
Message-ID: <20200418124205.GD6113@8bytes.org> (raw)
In-Reply-To: <20200414122506.438134-4-hch@lst.de>
Hi Christoph,
On Tue, Apr 14, 2020 at 02:25:05PM +0200, Christoph Hellwig wrote:
> +static inline bool dma_map_direct(struct device *dev,
> + const struct dma_map_ops *ops)
> +{
> + if (likely(!ops))
> + return true;
> + if (!dev->dma_ops_bypass)
> + return false;
> +
> + return min_not_zero(*dev->dma_mask, dev->bus_dma_limit) >=
> + dma_direct_get_required_mask(dev);
Why is the dma-mask check done here? The dma-direct code handles memory
outside of the devices dma-mask with swiotlb, no?
I also don't quite get what the difference between setting the
dma_ops_bypass flag non-zero and setting ops to NULL is.
Joerg
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next prev parent reply other threads:[~2020-04-18 12:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 12:25 generic DMA bypass flag v3 Christoph Hellwig
2020-04-14 12:25 ` [PATCH 1/4] dma-mapping: move the remaining DMA API calls out of line Christoph Hellwig
2020-04-15 2:26 ` Alexey Kardashevskiy
2020-04-15 6:18 ` Christoph Hellwig
2020-04-15 11:21 ` Alexey Kardashevskiy
2020-04-17 7:58 ` Christoph Hellwig
2020-05-05 4:18 ` Alexey Kardashevskiy
2020-05-09 8:19 ` Christoph Hellwig
2020-05-09 14:07 ` Alexey Kardashevskiy
2020-06-03 4:13 ` Alexey Kardashevskiy
2020-07-07 0:43 ` Alexey Kardashevskiy
2020-07-07 14:51 ` Christoph Hellwig
2020-04-14 12:25 ` [PATCH 2/4] dma-mapping: inline the fast path dma-direct calls Christoph Hellwig
2020-04-14 12:25 ` [PATCH 3/4] dma-mapping: add a dma_ops_bypass flag to struct device Christoph Hellwig
2020-04-14 12:47 ` Greg Kroah-Hartman
2020-04-18 12:42 ` Joerg Roedel [this message]
2020-04-19 8:00 ` Christoph Hellwig
2020-04-19 12:25 ` Joerg Roedel
2020-04-19 14:46 ` Alexey Kardashevskiy
2020-04-14 12:25 ` [PATCH 4/4] powerpc: use the generic dma_ops_bypass mode Christoph Hellwig
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