Messages in this thread | | | Date | Fri, 24 Mar 2023 11:17:32 +0000 | Subject | Re: [PATCH] iommu/rockchip: Add missing set_platform_dma_ops callback | From | Steven Price <> |
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On 22/03/2023 17:36, Jason Gunthorpe wrote: > On Wed, Mar 22, 2023 at 04:04:25PM +0000, Steven Price wrote: >> On 22/03/2023 15:16, Jason Gunthorpe wrote: >>> On Wed, Mar 22, 2023 at 03:08:41PM +0000, Steven Price wrote: >>>> @@ -1035,8 +1055,9 @@ static int rk_iommu_attach_device(struct iommu_domain *domain, >>>> if (iommu->domain == domain) >>>> return 0; >>>> >>>> - if (iommu->domain) >>>> - rk_iommu_detach_device(iommu->domain, dev); >>>> + ret = rk_iommu_identity_attach(&rk_identity_domain, dev); >>>> + if (ret) >>>> + return ret; >>> >>>> >>>> iommu->domain = domain; >>>> >>>> @@ -1049,8 +1070,6 @@ static int rk_iommu_attach_device(struct iommu_domain *domain, >>>> return 0; >>>> >>>> ret = rk_iommu_enable(iommu); >>>> - if (ret) >>>> - rk_iommu_detach_device(iommu->domain, dev); >>> >>> I think this still needs error handling, it should put it back to the >>> identity domain and return an error code if it fails to attach to the >>> requested domain. >> >> What confused me here is that there's already a call to >> rk_iommu_identity_attach() just above. But I can obviously add a... > > I don't know this driver at all, but to me it looks like this is > perhaps undoing a partially failed rk_iommu_enable() since it doesn't > seem to enetirely fix itself. Ie it zeros the INT_MASK and DTE_ADDR > > Maybe it would be better to put that error cleanup direclty into > enable and just move the iommu->domain assignment to after enable > success.
While I agree this would be better - I don't feel I understand the driver enough to have confidence in doing this. And I don't know how to trigger the error conditions to test this either.
>> if (ret) >> rk_iommu_identity_attach(&rk_identity_domain, dev); >> >> ... in here. But I don't know how to handle an error from >> rk_iommu_identity_attach() at this point. Does it need handling - is a >> WARN_ON sufficient? > > WARN_ON should be fine, that is kind of hacky, it would be better to > organize things so there is an identity attach function that cannot > fail, ie pre-assumes all the validation is done alread.y
As the code currently stands rk_iommu_identity_attach can fail for exactly one reason: if rk_iommu_from_dev() fails. And since that check is already done in rk_iommu_attach_device() this cannot fail (baring memory corruption etc). So I'll stick to WARN_ON for now.
>> >>> It should also initlaize iommu->domain to the identity domain when the >>> iommu struct is allocated. The iommu->domain should never be >>> NULL. identity domain means the IOMMU is turned off which was >>> previously called "detached". >> >> I presume you mean in rk_iommu_probe()? > > It would be best if it was setup at allocation time so in > rk_iommu_of_xlate() before dev_iommu_priv_set()
I've already put an assignment in rk_iommu_of_xlate() just before dev_iommu_priv_set().
Steve
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