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Date:   Fri, 9 Sep 2022 13:19:31 +0200
From:   Lorenzo Pieralisi <lpieralisi@kernel.org>
To:     Jianmin Lv <lvjianmin@loongson.cn>
Cc:     robin.murphy@arm.com, chenhuacai@loongson.cn, guohanjun@huawei.com,
        sudeep.holla@arm.com, rafael@kernel.org, lenb@kernel.org,
        robert.moore@intel.com, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, loongarch@lists.linux.dev
Subject: Re: [PATCH V4 1/2] ACPI / scan: Support multiple dma windows with
 different offsets
Message-ID: <YxshQ7IR1vtnimbh@lpieralisi>
References: <20220909092811.22627-1-lvjianmin@loongson.cn>
 <20220909092811.22627-2-lvjianmin@loongson.cn>
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In-Reply-To: <20220909092811.22627-2-lvjianmin@loongson.cn>
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On Fri, Sep 09, 2022 at 05:28:10PM +0800, Jianmin Lv wrote:
> For DT, of_dma_get_range returns bus_dma_region typed dma regions,
> which makes multiple dma windows with different offset available
> for translation between dma address and cpu address.
> 
> But for ACPI, acpi_dma_get_range doesn't return similar dma regions,
> causing no path for setting dev->dma_range_map conveniently. So the
> patch changes acpi_dma_get_range and returns bus_dma_region typed
> dma regions according to of_dma_get_range.
> 
> After changing acpi_dma_get_range, acpi_arch_dma_setup is changed for
> ARM64, where original dma_addr and size are removed as these
> arguments are now redundant, and pass 0 and U64_MAX for dma_base
> and size of arch_setup_dma_ops, so this is a simplification consistent
> with what other ACPI architectures also pass to iommu_setup_dma_ops().

How about this commit log:

"In DT systems configurations, of_dma_get_range() returns struct
bus_dma_region DMA regions; they are used to set-up devices
DMA windows with different offset available for translation between DMA
address and CPU address.

In ACPI systems configuration, acpi_dma_get_range() does not return
DMA regions yet and that precludes setting up the dev->dma_range_map
pointer and therefore DMA regions with multiple offsets.

Update acpi_dma_get_range() to return struct bus_dma_region
DMA regions like of_dma_get_range() does.

After updating acpi_dma_get_range(), acpi_arch_dma_setup() is changed for
ARM64, where the original dma_addr and size are removed as these
arguments are now redundant, and pass 0 and U64_MAX for dma_base
and size of arch_setup_dma_ops; this is a simplification consistent
with what other ACPI architectures also pass to iommu_setup_dma_ops()."

> 
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
> ---
>  drivers/acpi/arm64/dma.c | 29 +++++++++++++---------
>  drivers/acpi/scan.c      | 53 +++++++++++++++++-----------------------
>  include/acpi/acpi_bus.h  |  3 +--
>  include/linux/acpi.h     |  7 +++---
>  4 files changed, 45 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c
> index f16739ad3cc0..1ef8e7ded4cd 100644
> --- a/drivers/acpi/arm64/dma.c
> +++ b/drivers/acpi/arm64/dma.c
> @@ -4,11 +4,12 @@
>  #include <linux/device.h>
>  #include <linux/dma-direct.h>
>  
> -void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
> +void acpi_arch_dma_setup(struct device *dev)
>  {
>  	int ret;
>  	u64 end, mask;
> -	u64 dmaaddr = 0, size = 0, offset = 0;
> +	u64 size = 0;
> +	const struct bus_dma_region *map = NULL;
>  
>  	/*
>  	 * If @dev is expected to be DMA-capable then the bus code that created
> @@ -26,25 +27,31 @@ void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>  	else
>  		size = 1ULL << 32;
>  
> -	ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> +	ret = acpi_dma_get_range(dev, &map);
> +	if (!ret && map) {
> +		const struct bus_dma_region *r = map;
> +
> +		for (end = 0; r->size; r++) {
> +			if (r->dma_start + r->size - 1 > end)
> +				end = r->dma_start + r->size - 1;
> +		}
> +
> +		size = end + 1;
> +		dev->dma_range_map = map;
> +	}
> +
>  	if (ret == -ENODEV)
>  		ret = iort_dma_get_ranges(dev, &size);
> +

Nit: this is a spurious line change.

>  	if (!ret) {
>  		/*
>  		 * Limit coherent and dma mask based on size retrieved from
>  		 * firmware.
>  		 */
> -		end = dmaaddr + size - 1;
> +		end = size - 1;
>  		mask = DMA_BIT_MASK(ilog2(end) + 1);
>  		dev->bus_dma_limit = end;
>  		dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask);
>  		*dev->dma_mask = min(*dev->dma_mask, mask);
>  	}
> -
> -	*dma_addr = dmaaddr;
> -	*dma_size = size;
> -
> -	ret = dma_direct_set_offset(dev, dmaaddr + offset, dmaaddr, size);
> -
> -	dev_dbg(dev, "dma_offset(%#08llx)%s\n", offset, ret ? " failed!" : "");
>  }
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 42cec8120f18..b4505ec467fe 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -20,6 +20,7 @@
>  #include <linux/platform_data/x86/apple.h>
>  #include <linux/pgtable.h>
>  #include <linux/crc32.h>
> +#include <linux/dma-direct.h>
>  
>  #include "internal.h"
>  
> @@ -1467,25 +1468,21 @@ enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
>   * acpi_dma_get_range() - Get device DMA parameters.
>   *
>   * @dev: device to configure
> - * @dma_addr: pointer device DMA address result
> - * @offset: pointer to the DMA offset result
> - * @size: pointer to DMA range size result
> + * @map: pointer to DMA ranges result
>   *
> - * Evaluate DMA regions and return respectively DMA region start, offset
> - * and size in dma_addr, offset and size on parsing success; it does not
> - * update the passed in values on failure.
> + * Evaluate DMA regions and return pointer to DMA regions on
> + * parsing success; it does not update the passed in values on failure.
>   *
>   * Return 0 on success, < 0 on failure.
>   */
> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
> -		       u64 *size)
> +int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
>  {
>  	struct acpi_device *adev;
>  	LIST_HEAD(list);
>  	struct resource_entry *rentry;
>  	int ret;
>  	struct device *dma_dev = dev;
> -	u64 len, dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
> +	struct bus_dma_region *r;
>  
>  	/*
>  	 * Walk the device tree chasing an ACPI companion with a _DMA
> @@ -1510,31 +1507,28 @@ int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
>  
>  	ret = acpi_dev_get_dma_resources(adev, &list);
>  	if (ret > 0) {
> +		r = kcalloc(ret + 1, sizeof(*r), GFP_KERNEL);

Why (ret + 1) ?

> +		if (!r) {
> +			ret = -ENOMEM;
> +			goto out;
> +		}
> +
> +		*map = r;

I don't think that's right. This function can still fail at this stage,
we should not update the *map value yet.

Lorenzo

> +
>  		list_for_each_entry(rentry, &list, node) {
> -			if (dma_offset && rentry->offset != dma_offset) {
> +			if (rentry->res->start >= rentry->res->end) {
>  				ret = -EINVAL;
> -				dev_warn(dma_dev, "Can't handle multiple windows with different offsets\n");
> +				dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
>  				goto out;
>  			}
> -			dma_offset = rentry->offset;
>  
> -			/* Take lower and upper limits */
> -			if (rentry->res->start < dma_start)
> -				dma_start = rentry->res->start;
> -			if (rentry->res->end > dma_end)
> -				dma_end = rentry->res->end;
> -		}
> -
> -		if (dma_start >= dma_end) {
> -			ret = -EINVAL;
> -			dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
> -			goto out;
> +			r->cpu_start = rentry->res->start;
> +			r->dma_start = rentry->res->start - rentry->offset;
> +			r->size = resource_size(rentry->res);
> +			r->offset = rentry->offset;
> +			r++;
>  		}
>  
> -		*dma_addr = dma_start - dma_offset;
> -		len = dma_end - dma_start;
> -		*size = max(len, len + 1);
> -		*offset = dma_offset;
>  	}
>   out:
>  	acpi_dev_free_resource_list(&list);
> @@ -1624,20 +1618,19 @@ int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
>  			  const u32 *input_id)
>  {
>  	const struct iommu_ops *iommu;
> -	u64 dma_addr = 0, size = 0;
>  
>  	if (attr == DEV_DMA_NOT_SUPPORTED) {
>  		set_dma_ops(dev, &dma_dummy_ops);
>  		return 0;
>  	}
>  
> -	acpi_arch_dma_setup(dev, &dma_addr, &size);
> +	acpi_arch_dma_setup(dev);
>  
>  	iommu = acpi_iommu_configure_id(dev, input_id);
>  	if (PTR_ERR(iommu) == -EPROBE_DEFER)
>  		return -EPROBE_DEFER;
>  
> -	arch_setup_dma_ops(dev, dma_addr, size,
> +	arch_setup_dma_ops(dev, 0, U64_MAX,
>  				iommu, attr == DEV_DMA_COHERENT);
>  
>  	return 0;
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index e7d27373ff71..73ac4a1d6947 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -613,8 +613,7 @@ enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev);
>  int acpi_iommu_fwspec_init(struct device *dev, u32 id,
>  			   struct fwnode_handle *fwnode,
>  			   const struct iommu_ops *ops);
> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
> -		       u64 *size);
> +int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map);
>  int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
>  			   const u32 *input_id);
>  static inline int acpi_dma_configure(struct device *dev,
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 6f64b2f3dc54..bb41623dab77 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -281,12 +281,12 @@ void acpi_numa_x2apic_affinity_init(struct acpi_srat_x2apic_cpu_affinity *pa);
>  
>  #ifdef CONFIG_ARM64
>  void acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa);
> -void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size);
> +void acpi_arch_dma_setup(struct device *dev);
>  #else
>  static inline void
>  acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa) { }
>  static inline void
> -acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size) { }
> +acpi_arch_dma_setup(struct device *dev) { }
>  #endif
>  
>  int acpi_numa_memory_affinity_init (struct acpi_srat_mem_affinity *ma);
> @@ -977,8 +977,7 @@ static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
>  	return DEV_DMA_NOT_SUPPORTED;
>  }
>  
> -static inline int acpi_dma_get_range(struct device *dev, u64 *dma_addr,
> -				     u64 *offset, u64 *size)
> +static inline int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
>  {
>  	return -ENODEV;
>  }
> -- 
> 2.31.1
>