Hi Shunqian,
On Wed, Jun 15, 2016 at 9:04 PM, Shunqian Zheng <zhengsq@xxxxxxxxxxxxxx> wrote:
> Use DMA API instead of architecture internal functions like
> __cpuc_flush_dcache_area() etc.
>
> To support the virtual device like DRM the virtual slave iommu
> added in the previous patch, attaching to which the DRM can use
> it own domain->dev for dma_map_*(), dma_sync_*() even VOP is disabled.
>
> With this patch, this driver is available for ARM64 like RK3399.
>
> Signed-off-by: Shunqian Zheng <zhengsq@xxxxxxxxxxxxxx>
> ---
> drivers/iommu/rockchip-iommu.c | 113 +++++++++++++++++++++++++++--------------
> 1 file changed, 76 insertions(+), 37 deletions(-)
In general looks good to me, but still have some concern about
attaching and detaching. Please see inline.
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index 82ecc99..b60b29e 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
[snip]
> @@ -886,6 +901,22 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
> return -ENOMEM;
> }
>
> + /* Set the domain dev to virtual one if exist */
> + if (rk_iommu_is_virtual(iommu) || !rk_domain->dev)
Does it matter if the iommu is virtual or not? This condition will
always evaluate to true on first attach anyway, so there might be
times when rk_domain->dev points to a real device.
> + rk_domain->dev = iommu->dev;
> +
[snip]
> static void rk_iommu_detach_device(struct iommu_domain *domain,
> @@ -987,8 +1023,6 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
> if (!rk_domain->dt)
> goto err_dt;
>
> - rk_table_flush(rk_domain->dt, NUM_DT_ENTRIES);
> -
> spin_lock_init(&rk_domain->iommus_lock);
> spin_lock_init(&rk_domain->dt_lock);
> INIT_LIST_HEAD(&rk_domain->iommus);
> @@ -1012,10 +1046,15 @@ static void rk_iommu_domain_free(struct iommu_domain *domain)
> if (rk_dte_is_pt_valid(dte)) {
> phys_addr_t pt_phys = rk_dte_pt_address(dte);
> u32 *page_table = phys_to_virt(pt_phys);
> + dma_unmap_single(rk_domain->dev, pt_phys,
> + SPAGE_SIZE, DMA_TO_DEVICE);
> free_page((unsigned long)page_table);
> }
> }
>
> + if (!rk_domain->dt_dma)
> + dma_unmap_single(rk_domain->dev, rk_domain->dt_dma,
> + SPAGE_SIZE, DMA_TO_DEVICE);
> free_page((unsigned long)rk_domain->dt);
>
> iommu_put_dma_cookie(&rk_domain->domain);
If we detach here a device whose IOMMU is currently pointed by
rk_domain->dev, then the pointer will not point to anything valid
anymore. To be honest, I don't see any good solution for this. Maybe
we should keep all the IOMMUs in a list and set the ->dev pointer to
any from the list here?
Best regards,
Tomasz
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