From: Florian Fainelli <f.fainelli@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-arm-kernel@lists.infradead.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
"open list:SWIOTLB SUBSYSTEM" <iommu@lists.linux-foundation.org>,
open list <linux-kernel@vger.kernel.org>,
Russell King <linux@armlinux.org.uk>,
Mike Rapoport <rppt@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ard Biesheuvel <ardb@kernel.org>,
Max Filippov <jcmvbkbc@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
opendmb@gmail.com
Subject: Re: [PATCH] ARM: Qualify enabling of swiotlb_init()
Date: Fri, 19 Mar 2021 10:43:22 -0700 [thread overview]
Message-ID: <d4308ead-d561-19f6-510c-45e61613de54@gmail.com> (raw)
In-Reply-To: <20210319130731.GB2624@lst.de>
On 3/19/2021 6:07 AM, Christoph Hellwig wrote:
> On Thu, Mar 18, 2021 at 09:03:33PM -0700, Florian Fainelli wrote:
>> #ifdef CONFIG_ARM_LPAE
>> + if (swiotlb_force == SWIOTLB_FORCE ||
>> + max_pfn > arm_dma_pfn_limit)
>
> Does arm_dma_pfn_limit do the right thing even with the weirdest
> remapping ranges? Maybe a commen here would be useful.
It gets assigned to either 0xffffffff or PHYS_OFFSET + arm_dma_zone_size
- 1 which is obtained from the machine descriptor, so I expect it to do
the right thing, it works for a Pi 4 in 32-bit mode for instance. This
is conditional upon enabling CONFIG_ZONE_DMA for ARM, and will otherwise
keep its original value of 0, so this should be safe AFAICT.
>
>> + swiotlb_init(1);
>> + else
>> + swiotlb_force = SWIOTLB_NO_FORCE;
>
> Konrad: what do you think of setting swiotlb_force to SWIOTLB_NO_FORCE
> and only switching it to SWIOTLB_NORMAL when swiotlb_init* is called?
> That kind makes more sense than forcing the callers to do it.
>
> While we're at it, I think swiotlb_force should probably be renamed to
> swiotlb_mode or somethng like that.
Agreed.
--
Florian
next prev parent reply other threads:[~2021-03-19 17:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 4:03 [PATCH] ARM: Qualify enabling of swiotlb_init() Florian Fainelli
2021-03-19 13:07 ` Christoph Hellwig
2021-03-19 17:43 ` Florian Fainelli [this message]
2021-03-19 19:59 ` Konrad Rzeszutek Wilk
2021-03-20 0:22 ` Stefano Stabellini
2021-03-29 19:30 ` Florian Fainelli
2021-03-30 5:36 ` Christoph Hellwig
2021-04-01 17:33 ` Konrad Rzeszutek Wilk
2021-04-01 19:11 ` Florian Fainelli
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