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From: Rob Herring <robh+dt@kernel.org>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: devicetree@vger.kernel.org, Frank Rowand <frowand.list@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Jeremy Linton <jeremy.linton@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Linux IOMMU <iommu@lists.linux-foundation.org>,
	"moderated list:BROADCOM BCM2835 ARM ARCHITECTURE"
	<linux-rpi-kernel@lists.infradead.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()
Date: Wed, 14 Oct 2020 17:02:48 -0500
Message-ID: <CAL_JsqKMGSCTmKF2Lt8GQFx0DVFFH1bLVBw=bRDM7upahGvKDQ@mail.gmail.com> (raw)
In-Reply-To: <20201014191211.27029-4-nsaenzjulienne@suse.de>

On Wed, Oct 14, 2020 at 2:12 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> Introduce of_dma_get_max_cpu_address(), which provides the highest CPU
> physical address addressable by all DMA masters in the system. It's
> specially useful for setting memory zones sizes at early boot time.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
>
> ---
>
> Changes since v2:
>  - Use PHYS_ADDR_MAX
>  - return phys_dma_t
>  - Rename function
>  - Correct subject
>  - Add support to start parsing from an arbitrary device node in order
>    for the function to work with unit tests
>
>  drivers/of/address.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of.h   |  7 +++++++
>  2 files changed, 49 insertions(+)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index eb9ab4f1e80b..b5a9695aaf82 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -1024,6 +1024,48 @@ int of_dma_get_range(struct device_node *np, const struct bus_dma_region **map)
>  }
>  #endif /* CONFIG_HAS_DMA */
>
> +/**
> + * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
> + * @np: The node to start searching from or NULL to start from the root
> + *
> + * Gets the highest CPU physical address that is addressable by all DMA masters
> + * in the system (or subtree when np is non-NULL). If no DMA constrained device
> + * is found, it returns PHYS_ADDR_MAX.
> + */
> +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> +{
> +       phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;

One issue with using phys_addr_t is it may be 32-bit even though the
DT is 64-bit addresses. LPAE capable system with LPAE disabled. Maybe
the truncation is fine here? Maybe not.

> +       struct of_range_parser parser;
> +       phys_addr_t subtree_max_addr;
> +       struct device_node *child;
> +       phys_addr_t cpu_end = 0;
> +       struct of_range range;
> +       const __be32 *ranges;
> +       int len;
> +
> +       if (!np)
> +               np = of_root;
> +
> +       ranges = of_get_property(np, "dma-ranges", &len);

I'm not really following why you changed the algorithm here. You're
skipping disabled nodes which is good. Was there some other reason?

> +       if (ranges && len) {
> +               of_dma_range_parser_init(&parser, np);
> +               for_each_of_range(&parser, &range)
> +                       if (range.cpu_addr + range.size > cpu_end)
> +                               cpu_end = range.cpu_addr + range.size;
> +
> +               if (max_cpu_addr > cpu_end)
> +                       max_cpu_addr = cpu_end;
> +       }
> +
> +       for_each_available_child_of_node(np, child) {
> +               subtree_max_addr = of_dma_get_max_cpu_address(child);
> +               if (max_cpu_addr > subtree_max_addr)
> +                       max_cpu_addr = subtree_max_addr;
> +       }
> +
> +       return max_cpu_addr;
> +}
> +
>  /**
>   * of_dma_is_coherent - Check if device is coherent
>   * @np:        device node
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 481ec0467285..db8db8f2c967 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -558,6 +558,8 @@ int of_map_id(struct device_node *np, u32 id,
>                const char *map_name, const char *map_mask_name,
>                struct device_node **target, u32 *id_out);
>
> +phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
> +
>  #else /* CONFIG_OF */
>
>  static inline void of_core_init(void)
> @@ -995,6 +997,11 @@ static inline int of_map_id(struct device_node *np, u32 id,
>         return -EINVAL;
>  }
>
> +static inline phys_addr_t of_dma_get_max_cpu_address(struct device_node *np)
> +{
> +       return PHYS_ADDR_MAX;
> +}
> +
>  #define of_match_ptr(_ptr)     NULL
>  #define of_match_node(_matches, _node) NULL
>  #endif /* CONFIG_OF */
> --
> 2.28.0
>
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  reply index

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-14 19:12 [PATCH v3 0/8] arm64: Default to 32-bit wide ZONE_DMA Nicolas Saenz Julienne
2020-10-14 19:12 ` [PATCH v3 1/8] arm64: mm: Move reserve_crashkernel() into mem_init() Nicolas Saenz Julienne
2020-10-15  8:40   ` Will Deacon
2020-10-15  8:55     ` Nicolas Saenz Julienne
2020-10-14 19:12 ` [PATCH v3 2/8] arm64: mm: Move zone_dma_bits initialization into zone_sizes_init() Nicolas Saenz Julienne
2020-10-14 19:12 ` [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address() Nicolas Saenz Julienne
2020-10-14 22:02   ` Rob Herring [this message]
2020-10-15  6:56     ` Ard Biesheuvel
2020-10-15  9:16       ` Nicolas Saenz Julienne
2020-10-15  9:18         ` Ard Biesheuvel
2020-10-15  8:54     ` Nicolas Saenz Julienne
2020-10-15  5:42   ` Christoph Hellwig
2020-10-15 10:03     ` Nicolas Saenz Julienne
2020-10-16 13:19     ` Rob Herring
2020-10-14 19:12 ` [PATCH v3 4/8] of: unittest: Add test for of_dma_get_max_cpu_address() Nicolas Saenz Julienne
2020-10-14 22:04   ` Rob Herring
2020-10-15  9:51     ` Nicolas Saenz Julienne
2020-10-14 19:12 ` [PATCH v3 5/8] dma-direct: Turn zone_dma_bits default value into a define Nicolas Saenz Julienne
2020-10-15  5:38   ` Christoph Hellwig
2020-10-15 10:05     ` Nicolas Saenz Julienne
2020-10-14 19:12 ` [PATCH v3 6/8] arm64: mm: Set ZONE_DMA size based on devicetree's dma-ranges Nicolas Saenz Julienne
2020-10-15  5:39   ` Christoph Hellwig
2020-10-15 10:05     ` Nicolas Saenz Julienne
2020-10-14 19:12 ` [PATCH v3 7/8] arm64: mm: Set ZONE_DMA size based on early IORT scan Nicolas Saenz Julienne
2020-10-15 10:31   ` Lorenzo Pieralisi
2020-10-16  6:56     ` Ard Biesheuvel
2020-10-15 14:26   ` Hanjun Guo
2020-10-15 15:15     ` Nicolas Saenz Julienne
2020-10-15 18:03     ` Catalin Marinas
2020-10-16  6:51       ` Hanjun Guo
2020-10-16  6:54         ` Ard Biesheuvel
2020-10-16  7:27           ` Hanjun Guo
2020-10-16  7:34             ` Hanjun Guo
2020-10-14 19:12 ` [PATCH v3 8/8] mm: Update DMA zones description Nicolas Saenz Julienne
2020-10-15  5:40   ` Christoph Hellwig

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