Re: [PATCH v3 02/20] iommu/apple-dart: Remove detach_dev callback

Sven Peter
2022-11-30T17:07:30Z

Hi,

On Mon, Nov 28, 2022, at 07:46, Lu Baolu wrote:
> The IOMMU driver supports default domain, so the detach_dev op will never
> be called. Remove it to avoid dead code.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---

Reviewed-by: Sven Peter <sven@svenpeter.dev>

> drivers/iommu/apple-dart.c | 17 -----------------
> 1 file changed, 17 deletions(-)
>
> diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
> index 4f4a323be0d0..6fbe6b275c79 100644
> --- a/drivers/iommu/apple-dart.c
> +++ b/drivers/iommu/apple-dart.c
> @@ -535,22 +535,6 @@ static int apple_dart_attach_dev(struct
> iommu_domain *domain,
> return ret;
> }
>
> -static void apple_dart_detach_dev(struct iommu_domain *domain,
> - struct device *dev)
> -{

Thanks for cleaning this entire API up!

It actually turns out that this is slightly broken because I assumed that
detach_dev would always be called for any attach_dev. I think the only
consequence for a device that used to be assigned to domain A and is now moved to
domain B is that any TLB flushes required for A will still flush the TLB for that
device.

That's not a big deal but I'll eventually send a fix.

> - int i;
> - struct apple_dart_stream_map *stream_map;
> - struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
> - struct apple_dart_domain *dart_domain = to_dart_domain(domain);
> -
> - for_each_stream_map(i, cfg, stream_map)
> - apple_dart_hw_disable_dma(stream_map);
> -
> - if (domain->type == IOMMU_DOMAIN_DMA ||
> - domain->type == IOMMU_DOMAIN_UNMANAGED)
> - apple_dart_domain_remove_streams(dart_domain, cfg);

Something might complain about unused apple_dart_domain_remove_streams now.
Might make sense to drop that for now as well.

Best,

Sven