From: Christoph Hellwig <hch@lst.de>
To: "Petr Tesařík" <petr@tesarici.cz>
Cc: Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@lst.de>,
Petr Tesarik <petrtesarik@huaweicloud.com>,
Jonathan Corbet <corbet@lwn.net>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Borislav Petkov <bp@suse.de>,
"Paul E. McKenney" <paulmck@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Randy Dunlap <rdunlap@infradead.org>,
Damien Le Moal <damien.lemoal@opensource.wdc.com>,
Kim Phillips <kim.phillips@amd.com>,
"Steven Rostedt (Google)" <rostedt@goodmis.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
"open list:DMA MAPPING HELPERS" <iommu@lists.linux.dev>,
Roberto Sassu <roberto.sassu@huawei.com>,
Alexander Graf <graf@amazon.com>
Subject: Re: [RFC v1 3/4] swiotlb: Allow dynamic allocation of bounce buffers
Date: Mon, 24 Apr 2023 08:03:13 +0200 [thread overview]
Message-ID: <20230424060313.GB9805@lst.de> (raw)
In-Reply-To: <20230421170934.185a03a0@meshulam.tesarici.cz>
On Fri, Apr 21, 2023 at 05:09:34PM +0200, Petr Tesařík wrote:
> > > A. Only grouping those fields in their own struct?
> > > B. Or move the definition to another include file (cf. MAINTAINERS)?
> > > C. Or store a pointer in struct device?
> >
> > dev->dma_parms is already this, and IIRC still has some very old
> > comments somewhere about consolidating the other DMA-related fields in
> > there.
>
> Thank you for the hint! I have actually seen dma_parms, but since it
> can be NULL and was initialized from various drivers, it did not occur
> to me that NULL simply means not DMA-capable.
Yes, dma_parms are still optional. A much better hint is the dma_mask
itself, which for historic reasons is implemented in a completely
awfull way as a pointer to something stored in the containing struture,
which all kinds of platform devices or minor buses doing nasty hacks
there.
next prev parent reply other threads:[~2023-04-24 6:05 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 12:28 [RFC v1 0/4] Allow dynamic allocation of software IO TLB bounce buffers Petr Tesarik
2023-03-20 12:28 ` [RFC v1 1/4] dma-mapping: introduce the DMA_ATTR_MAY_SLEEP attribute Petr Tesarik
2023-03-28 3:57 ` Christoph Hellwig
2023-03-28 7:21 ` Petr Tesarik
2023-04-07 5:52 ` Christoph Hellwig
2023-03-31 13:06 ` Bagas Sanjaya
2023-03-20 12:28 ` [RFC v1 2/4] swiotlb: Move code around in preparation for dynamic bounce buffers Petr Tesarik
2023-03-20 12:28 ` [RFC v1 3/4] swiotlb: Allow dynamic allocation of " Petr Tesarik
2023-03-28 4:07 ` Christoph Hellwig
2023-03-28 7:54 ` Petr Tesarik
2023-03-28 12:43 ` Petr Tesarik
2023-04-07 5:57 ` Christoph Hellwig
2023-04-07 10:15 ` Petr Tesařík
2023-04-13 11:09 ` Petr Tesarik
2023-04-21 13:03 ` Petr Tesařík
2023-04-21 14:58 ` Robin Murphy
2023-04-21 15:09 ` Petr Tesařík
2023-04-24 6:03 ` Christoph Hellwig [this message]
2023-03-31 7:26 ` Juerg Haefliger
2023-03-31 9:00 ` Petr Tesařík
2023-04-06 11:44 ` Juerg Haefliger
2023-05-11 10:36 ` Petr Tesařík
2023-04-07 5:55 ` Christoph Hellwig
2023-04-07 10:46 ` Petr Tesařík
2023-04-11 3:51 ` Christoph Hellwig
2023-03-20 12:28 ` [RFC v1 4/4] swiotlb: Add an option to allow dynamic " Petr Tesarik
2023-03-27 11:06 ` [RFC v1 0/4] Allow dynamic allocation of software IO TLB " Petr Tesarik
2023-04-07 6:00 ` Christoph Hellwig
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