From: Jason Gunthorpe <jgg@ziepe.ca>
To: Steven Price <steven.price@arm.com>
Cc: Heiko Stuebner <heiko@sntech.de>, Joerg Roedel <joro@8bytes.org>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org,
Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: [PATCH] iommu/rockchip: Add missing set_platform_dma_ops callback
Date: Wed, 22 Mar 2023 09:50:03 -0300 [thread overview]
Message-ID: <ZBr5e6tn1i7EE/16@ziepe.ca> (raw)
In-Reply-To: <85607806-b888-2d5e-67a4-e9d63ebd1976@arm.com>
On Wed, Mar 22, 2023 at 09:02:41AM +0000, Steven Price wrote:
> On 21/03/2023 14:38, Jason Gunthorpe wrote:
> > On Wed, Mar 15, 2023 at 04:41:52PM +0000, Steven Price wrote:
> >> Similar to exynos, we need a set_platform_dma_ops() callback for proper
> >> operation on ARM 32 bit after recent changes in the IOMMU framework
> >> (detach ops removal).
> >>
> >> Fixes: c1fe9119ee70 ("iommu: Add set_platform_dma_ops callbacks")
> >> Signed-off-by: Steven Price <steven.price@arm.com>
> >> ---
> >> This fixes a splat I was seeing on a Firefly-RK3288, more details here:
> >> https://lore.kernel.org/all/26a5d1b8-40b3-b1e4-bc85-740409c26838@arm.com/
> >
> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
>
> Thanks for the review.
>
> > Do you know what state the iommu is left in after
> > rk_iommu_detach_device()? Ie is it blocking DMA or doing identity or
> > something else?
>
> To be honest I really don't know for sure. But from my small
> understanding of the code: rk_iommu_detach_device() ends up in
> rk_iommu_disable_paging() which appears to switch to identity mode
> ("Disable memory translation").
Can you consider writing this patch like this instead:
https://lore.kernel.org/linux-iommu/ZBnef7g7GCxogPNz@ziepe.ca/
?
I'd much rather we move toward clearly documenting what is going on
with the HW and remove this undefined "detach" language.
Jason
next prev parent reply other threads:[~2023-03-22 12:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-15 16:41 [PATCH] iommu/rockchip: Add missing set_platform_dma_ops callback Steven Price
2023-03-21 14:38 ` Jason Gunthorpe
2023-03-22 9:02 ` Steven Price
2023-03-22 12:50 ` Jason Gunthorpe [this message]
2023-03-22 15:08 ` Steven Price
2023-03-22 15:16 ` Jason Gunthorpe
2023-03-22 16:04 ` Steven Price
2023-03-22 17:36 ` Jason Gunthorpe
2023-03-24 11:17 ` Steven Price
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