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

From: Baolu Lu <baolu.lu@linux.intel.com>
To: Sven Peter <sven@svenpeter.dev>, Joerg Roedel <joro@8bytes.org>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Christoph Hellwig <hch@infradead.org>,
	Kevin Tian <kevin.tian@intel.com>, Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: baolu.lu@linux.intel.com,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Hector Martin <marcan@marcan.st>, Rob Clark <robdclark@gmail.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Yong Wu <yong.wu@mediatek.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Heiko Stuebner <heiko@sntech.de>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	Orson Zhai <orsonzhai@gmail.com>,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	Chunyan Zhang <zhang.lyra@gmail.com>,
	Chen-Yu Tsai <wens@csie.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 02/20] iommu/apple-dart: Remove detach_dev callback
Date: Thu, 1 Dec 2022 12:50:52 +0800	[thread overview]
Message-ID: <b3b2226e-7eee-f24c-9f61-8b968ef6af9c@linux.intel.com> (raw)
In-Reply-To: <e255ed09-ed67-46b3-b055-287959d1b76f@app.fastmail.com>

On 2022/12/1 1:00, Sven Peter wrote:
> 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.

Done. Thanks!

Best regards,
baolu