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Subject: Re: [PATCH] ACPI / scan: Support multiple dma windows with different
 offsets
To:     Robin Murphy <robin.murphy@arm.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc:     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
References: <1659255431-22796-1-git-send-email-lvjianmin@loongson.cn>
 <e12706ef-70de-08b6-ada0-818d03b8c2f5@loongson.cn>
 <YuvJLxa5zsMj1pGf@lpieralisi> <a26d8edc-a3a6-8f95-0e7a-c9f60ee04462@arm.com>
From:   Jianmin Lv <lvjianmin@loongson.cn>
Message-ID: <6270ec4d-b322-0b85-6597-5ab2df744098@loongson.cn>
Date:   Fri, 5 Aug 2022 15:16:52 +0800
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On 2022/8/5 上午2:26, Robin Murphy wrote:
> On 04/08/2022 2:27 pm, Lorenzo Pieralisi wrote:
>> [+Robin]
>>
>> On Thu, Aug 04, 2022 at 05:59:23PM +0800, Jianmin Lv wrote:
>>> Hi, all
>>>
>>> Can anybody help to review the patch, or I missed somebody else?
>>
>> I will review the patch - added Robin since it affects the DMA
>> ranges handling.
> 
> Thanks Lorenzo!
> 
>>
>> Lorenzo
>>
>>> Thanks!
>>>
>>> On 2022/7/31 下午4:17, 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, original part of internal code
>>>> only available for ARM is moved to acpi_arch_dma_setup for remaining
>>>> unchanged.
> 
> This seems a bit silly. If we've finally done the work to parse a proper 
> dma_range_map, we can use it; no need to artificially maintain the old 
> dma_pfn_offset limitation. TBH I wouldn't even preserve the dmaaddr and 
> size calculations as they are either, just set dev->bus_dma_limit based 
> on the highest entry in the map, and pass 0 and U64_MAX to 
> arch_setup_dma_ops() since those are basically meaningless now (I plan 
> to remove them entirely once I unpick the IOMMU setup).
> 
> Thanks,
> Robin.
> 

Ok, thanks, I'll change the patch as your suggestion in next revision.


>>>> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
>>>>
>>>> diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c
>>>> index f16739a..840f918 100644
>>>> --- a/drivers/acpi/arm64/dma.c
>>>> +++ b/drivers/acpi/arm64/dma.c
>>>> @@ -9,6 +9,7 @@ void acpi_arch_dma_setup(struct device *dev, u64 
>>>> *dma_addr, u64 *dma_size)
>>>>        int ret;
>>>>        u64 end, mask;
>>>>        u64 dmaaddr = 0, size = 0, offset = 0;
>>>> +    const struct bus_dma_region *map = NULL;
>>>>        /*
>>>>         * If @dev is expected to be DMA-capable then the bus code 
>>>> that created
>>>> @@ -26,10 +27,37 @@ 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 == -ENODEV)
>>>>            ret = iort_dma_get_ranges(dev, &size);
>>>>        if (!ret) {
>>>> +        const struct bus_dma_region *r = map;
>>>> +        u64 len, dma_start, dma_end = 0;
>>>> +
>>>> +        /* determine the overall bounds of all dma regions */
>>>> +        for (dma_start = U64_MAX; r->size; r++) {
>>>> +            if (offset && r->offset != offset) {
>>>> +                dev_warn(dev, "Can't handle multiple windows with 
>>>> different offsets\n");
>>>> +                return;
>>>> +            }
>>>> +            offset = r->offset;
>>>> +
>>>> +            /* Take lower and upper limits */
>>>> +            if (r->dma_start < dma_start)
>>>> +                dma_start = r->dma_start;
>>>> +            if (r->dma_start + r->size - 1 > dma_end)
>>>> +                dma_end = r->dma_start + r->size - 1;
>>>> +        }
>>>> +
>>>> +        if (dma_start >= dma_end) {
>>>> +            dev_dbg(dev, "Invalid DMA regions configuration\n");
>>>> +            return;
>>>> +        }
>>>> +
>>>> +        dmaaddr = dma_start;
>>>> +        len = dma_end - dma_start;
>>>> +        size = max(len, len + 1);
>>>> +
>>>>            /*
>>>>             * Limit coherent and dma mask based on size retrieved from
>>>>             * firmware.
>>>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
>>>> index 762b61f..8961b51 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"
>>>> @@ -1492,15 +1493,15 @@ enum dev_dma_attr acpi_get_dma_attr(struct 
>>>> acpi_device *adev)
>>>>     *
>>>>     * 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;
>>>> +    int num_ranges = 0;
>>>> +    struct bus_dma_region *r;
>>>>        /*
>>>>         * Walk the device tree chasing an ACPI companion with a _DMA
>>>> @@ -1525,31 +1526,31 @@ int acpi_dma_get_range(struct device *dev, 
>>>> u64 *dma_addr, u64 *offset,
>>>>        ret = acpi_dev_get_dma_resources(adev, &list);
>>>>        if (ret > 0) {
>>>> +        list_for_each_entry(rentry, &list, node)
>>>> +            num_ranges++;
>>>> +
>>>> +        r = kcalloc(num_ranges + 1, sizeof(*r), GFP_KERNEL);
>>>> +        if (!r) {
>>>> +            ret = -ENOMEM;
>>>> +            goto out;
>>>> +        }
>>>> +
>>>> +        *map = r;
>>>> +
>>>>            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 = rentry->res->end - rentry->res->start + 1;
>>>> +            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);
>>>> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
>>>> index 0dc1ea0b..e106073 100644
>>>> --- a/include/acpi/acpi_bus.h
>>>> +++ b/include/acpi/acpi_bus.h
>>>> @@ -611,8 +611,7 @@ struct acpi_pci_root {
>>>>    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 44975c1..f806092 100644
>>>> --- a/include/linux/acpi.h
>>>> +++ b/include/linux/acpi.h
>>>> @@ -974,8 +974,7 @@ 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;
>>>>    }
>>>>
>>>