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SubjectRe: [PATCH v2] iommu/rockchip: Add missing set_platform_dma_ops callback
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On 2023/3/24 19:11, 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). But also the use of a NULL domain is confusing.
>
> Rework the code to have a singleton rk_identity_domain which is assigned
> to domain when using an identity mapping rather than "detaching". This
> makes the code easier to reason about.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> Changes since v1[1]:
>
> * Reworked the code to avoid a NULL domain, instead a singleton
> rk_identity_domain is used instead. The 'detach' language is no
> longer used.
>
> [1] https://lore.kernel.org/r/20230315164152.333251-1-steven.price%40arm.com
>
> drivers/iommu/rockchip-iommu.c | 50 ++++++++++++++++++++++++++--------
> 1 file changed, 39 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index f30db22ea5d7..437541004994 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -124,6 +124,7 @@ struct rk_iommudata {
>
> static struct device *dma_dev;
> static const struct rk_iommu_ops *rk_ops;
> +static struct iommu_domain rk_identity_domain;
>
> static inline void rk_table_flush(struct rk_iommu_domain *dom, dma_addr_t dma,
> unsigned int count)
> @@ -980,26 +981,27 @@ static int rk_iommu_enable(struct rk_iommu *iommu)
> return ret;
> }
>
> -static void rk_iommu_detach_device(struct iommu_domain *domain,
> - struct device *dev)
> +static int rk_iommu_identity_attach(struct iommu_domain *identity_domain,
> + struct device *dev)
> {
> struct rk_iommu *iommu;
> - struct rk_iommu_domain *rk_domain = to_rk_domain(domain);
> + struct rk_iommu_domain *rk_domain;
> unsigned long flags;
> int ret;
>
> /* Allow 'virtual devices' (eg drm) to detach from domain */
> iommu = rk_iommu_from_dev(dev);
> if (!iommu)
> - return;
> + return -ENODEV;
> +
> + rk_domain = to_rk_domain(iommu->domain);
>
> dev_dbg(dev, "Detaching from iommu domain\n");
>
> - /* iommu already detached */
> - if (iommu->domain != domain)
> - return;
> + if (iommu->domain == identity_domain)
> + return 0;
>
> - iommu->domain = NULL;
> + iommu->domain = identity_domain;

Where did identity_domain come from? Is it rk_identity_domain?

Best regards,
baolu

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