Hi Tomasz:

On Fri, 2019-07-05 at 13:22 +0900, Tomasz Figa wrote:

Hi Jungo,

On Fri, Jul 5, 2019 at 12:33 PM Jungo Lin [off-list ref] wrote:

quoted

Hi Tomasz,

[snip]

quoted

After applying your suggestion in SCP device driver, we could remove
mtk_cam-smem.h/c. Currently, we use dma_alloc_coherent with SCP device
to get SCP address. We could touch the buffer with this SCP address in
SCP processor.

After that, we use dma_map_page_attrs with P1 device which supports
IOMMU domain to get IOVA address. For this address, we will assign
it to our ISP HW device to proceed.

Below is the snippet for ISP P1 compose buffer initialization.

        ptr = dma_alloc_coherent(p1_dev->cam_dev.smem_dev,
                                 MAX_COMPOSER_SIZE, &addr, GFP_KERNEL);
        if (!ptr) {
                dev_err(dev, "failed to allocate compose memory\n");
                return -ENOMEM;
        }
        isp_ctx->scp_mem_pa = addr;

addr contains a DMA address, not a physical address. Could we call it
scp_mem_dma instead?

quoted

        dev_dbg(dev, "scp addr:%pad\n", &addr);

        /* get iova address */
        addr = dma_map_page_attrs(dev, phys_to_page(addr), 0,

addr is a DMA address, so phys_to_page() can't be called on it. The
simplest thing here would be to use dma_map_single() with ptr as the
CPU address expected.

We have changed to use ma_map_single() with ptr, but encounter IOMMU
error. From the debug log of iommu_dma_map_page[3], we got
0x0000000054800000 instead of expected address: 0x0000000050800000[2].
There is a address offset(0x4000000). If we change to use
dma_map_page_attrs with phys_to_page(addr), the address is correct as we
expected[2]. Do you have any suggestion on this issue? Do we miss
something?

[1]
[    1.344786] __dma_alloc_from_coherent: 0x800000 PAGE_SHIFT:12
device_base:0x0000000050000000 dma:0x0000000050800000
virt_base:ffffff8014000000 va:ffffff8014800000

[    1.346890] mtk-cam 1a000000.camisp: scp addr:0x0000000050800000
va:ffffff8014800000

[    1.347864] iommu_dma_map_page:0x0000000054800000 offset:0
[    1.348562] mtk-cam 1a000000.camisp: iova addr:0x00000000fde00000

[2]
[    1.346738] __dma_alloc_from_coherent: 0x800000 PAGE_SHIFT:12
device_base:0x0000000050000000 dma:0x0000000050800000
virt_base:ffffff8014000000 va:ffffff8014800000
[    1.348841] mtk-cam 1a000000.camisp: scp addr:0x0000000050800000
va:ffffff8014800000
[    1.349816] iommu_dma_map_page:0x0000000050800000 offset:0
[    1.350514] mtk-cam 1a000000.camisp: iova addr:0x00000000fde00000


[3]
dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
		unsigned long offset, size_t size, int prot)
{
	phys_addr_t phys = page_to_phys(page);
	pr_err("iommu_dma_map_page:%pa offset:%lu\n", &phys, offset);

	return __iommu_dma_map(dev, page_to_phys(page) + offset, size, prot,
			iommu_get_dma_domain(dev));
}

[snip]

Best regards,

Jungo


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