From: Christoph Hellwig <hch@lst.de>
To: Ben Dooks <ben.dooks@sifive.com>
Cc: Christoph Hellwig <hch@lst.de>,
Robin Murphy <robin.murphy@arm.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
iommu@lists.linux-foundation.org,
Sudip Mukherjee <sudip.mukherjee@sifive.com>,
Jude Onyenegecha <jude.onyenegecha@sifive.com>,
Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH] swiotlb: ensure io_tlb_default_mem spinlock always initialised
Date: Mon, 11 Jul 2022 12:39:21 +0200 [thread overview]
Message-ID: <20220711103921.GA6542@lst.de> (raw)
In-Reply-To: <4fa8b709-c883-54dc-c302-20c9e55ae93a@sifive.com>
On Mon, Jul 11, 2022 at 11:24:51AM +0100, Ben Dooks wrote:
> On 11/07/2022 11:21, Christoph Hellwig wrote:
>> On Mon, Jul 11, 2022 at 11:07:17AM +0100, Robin Murphy wrote:
>>> If none of your peripherals should need SWIOTLB, then the fact that
>>> you're ending up in swiotlb_map() at all is a clear sign that
>>> something's wrong. Most likely someone's forgotten to set their DMA
>>> masks correctly.
>>
>> Yes.
>
> Possibly, we had at least one driver which attempted to set a 32 bit
> DMA mask which had to be removed as the DMA layer accepts this but
> since there is no DMA32 memory the allocator then just fails.
>
> I expect the above may need to be a separate discussion(s) of how to
> default the DMA mask and how to stop the implicit acceptance of setting
> a 32-bit DMA mask.
No. Linux simply assumes you can do 32-bit DMA and this won't
change. So we'll need to fix your platform to support swiotlb
eventually.
next prev parent reply other threads:[~2022-07-11 10:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-08 17:08 [PATCH] swiotlb: ensure io_tlb_default_mem spinlock always initialised Ben Dooks
2022-07-08 20:32 ` Robin Murphy
2022-07-11 7:26 ` Ben Dooks
2022-07-11 10:07 ` Robin Murphy
2022-07-11 10:21 ` Christoph Hellwig
2022-07-11 10:24 ` Ben Dooks
2022-07-11 10:39 ` Christoph Hellwig [this message]
2022-07-11 10:42 ` Ben Dooks
2022-07-11 11:01 ` Robin Murphy
2022-07-11 11:52 ` Conor.Dooley
2022-07-11 12:45 ` Ben Dooks
2022-07-11 12:56 ` Conor.Dooley
2022-07-11 12:54 ` Ben Dooks
2022-07-11 13:40 ` Christoph Hellwig
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