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Date:   Thu, 17 Jun 2021 16:30:50 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@kernel.org>
To:     Claire Chang <tientzu@chromium.org>
cc:     Rob Herring <robh+dt@kernel.org>, mpe@ellerman.id.au,
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Subject: Re: [PATCH v13 03/12] swiotlb: Set dev->dma_io_tlb_mem to the swiotlb
 pool used
In-Reply-To: <20210617062635.1660944-4-tientzu@chromium.org>
Message-ID: <alpine.DEB.2.21.2106171444510.24906@sstabellini-ThinkPad-T480s>
References: <20210617062635.1660944-1-tientzu@chromium.org> <20210617062635.1660944-4-tientzu@chromium.org>
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Precedence: bulk

On Thu, 17 Jun 2021, Claire Chang wrote:
> Always have the pointer to the swiotlb pool used in struct device. This
> could help simplify the code for other pools.
> 
> Signed-off-by: Claire Chang <tientzu@chromium.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Tested-by: Stefano Stabellini <sstabellini@kernel.org>
> Tested-by: Will Deacon <will@kernel.org>

Acked-by: Stefano Stabellini <sstabellini@kernel.org>

> ---
>  drivers/base/core.c    | 4 ++++
>  include/linux/device.h | 4 ++++
>  kernel/dma/swiotlb.c   | 8 ++++----
>  3 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index f29839382f81..cb3123e3954d 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -27,6 +27,7 @@
>  #include <linux/netdevice.h>
>  #include <linux/sched/signal.h>
>  #include <linux/sched/mm.h>
> +#include <linux/swiotlb.h>
>  #include <linux/sysfs.h>
>  #include <linux/dma-map-ops.h> /* for dma_default_coherent */
>  
> @@ -2736,6 +2737,9 @@ void device_initialize(struct device *dev)
>      defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
>  	dev->dma_coherent = dma_default_coherent;
>  #endif
> +#ifdef CONFIG_SWIOTLB
> +	dev->dma_io_tlb_mem = io_tlb_default_mem;
> +#endif
>  }
>  EXPORT_SYMBOL_GPL(device_initialize);
>  
> diff --git a/include/linux/device.h b/include/linux/device.h
> index ba660731bd25..240d652a0696 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -416,6 +416,7 @@ struct dev_links_info {
>   * @dma_pools:	Dma pools (if dma'ble device).
>   * @dma_mem:	Internal for coherent mem override.
>   * @cma_area:	Contiguous memory area for dma allocations
> + * @dma_io_tlb_mem: Pointer to the swiotlb pool used.  Not for driver use.
>   * @archdata:	For arch-specific additions.
>   * @of_node:	Associated device tree node.
>   * @fwnode:	Associated device node supplied by platform firmware.
> @@ -518,6 +519,9 @@ struct device {
>  #ifdef CONFIG_DMA_CMA
>  	struct cma *cma_area;		/* contiguous memory area for dma
>  					   allocations */
> +#endif
> +#ifdef CONFIG_SWIOTLB
> +	struct io_tlb_mem *dma_io_tlb_mem;
>  #endif
>  	/* arch specific additions */
>  	struct dev_archdata	archdata;
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 2dba659a1e73..de79e9437030 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -340,7 +340,7 @@ void __init swiotlb_exit(void)
>  static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size,
>  			   enum dma_data_direction dir)
>  {
> -	struct io_tlb_mem *mem = io_tlb_default_mem;
> +	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
>  	int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT;
>  	unsigned int offset = (tlb_addr - mem->start) & (IO_TLB_SIZE - 1);
>  	phys_addr_t orig_addr = mem->slots[index].orig_addr;
> @@ -431,7 +431,7 @@ static unsigned int wrap_index(struct io_tlb_mem *mem, unsigned int index)
>  static int find_slots(struct device *dev, phys_addr_t orig_addr,
>  		size_t alloc_size)
>  {
> -	struct io_tlb_mem *mem = io_tlb_default_mem;
> +	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
>  	unsigned long boundary_mask = dma_get_seg_boundary(dev);
>  	dma_addr_t tbl_dma_addr =
>  		phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
> @@ -508,7 +508,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
>  		size_t mapping_size, size_t alloc_size,
>  		enum dma_data_direction dir, unsigned long attrs)
>  {
> -	struct io_tlb_mem *mem = io_tlb_default_mem;
> +	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
>  	unsigned int offset = swiotlb_align_offset(dev, orig_addr);
>  	unsigned int i;
>  	int index;
> @@ -559,7 +559,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
>  			      size_t mapping_size, enum dma_data_direction dir,
>  			      unsigned long attrs)
>  {
> -	struct io_tlb_mem *mem = io_tlb_default_mem;
> +	struct io_tlb_mem *mem = hwdev->dma_io_tlb_mem;
>  	unsigned long flags;
>  	unsigned int offset = swiotlb_align_offset(hwdev, tlb_addr);
>  	int index = (tlb_addr - offset - mem->start) >> IO_TLB_SHIFT;
> -- 
> 2.32.0.288.g62a8d224e6-goog
>