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    SubjectRe: [PATCH 1/2] mtd: mtk-quadspi: add support for memory-mapped flash reading
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    On 07/11/19 3:01 PM, Chuanhong Guo wrote:
    > Hi!
    >
    > On Thu, Nov 7, 2019 at 2:05 PM Vignesh Raghavendra <vigneshr@ti.com> wrote:
    >>> @@ -272,6 +273,11 @@ static ssize_t mtk_nor_read(struct spi_nor *nor, loff_t from, size_t length,
    >>> mtk_nor_set_read_mode(mtk_nor);
    >>> mtk_nor_set_addr(mtk_nor, addr);
    >>>
    >>> + if (mtk_nor->flash_base) {
    >>> + memcpy_fromio(buffer, mtk_nor->flash_base + from, length);
    >>> + return length;
    >>> + }
    >>> +
    >>
    >> Don't you need to check if access is still within valid memory mapped
    >> window?
    >
    > The mapped area is 256MB and I don't quite believe there will be such
    > a big NOR flash.
    > I'll add a check here in the next version.
    >


    There are 256MB (2GiB) NORs out there in market already. So, pretty
    soon, 256MB window won't be big enough :)

    >>
    >>> for (i = 0; i < length; i++) {
    >>> ret = mtk_nor_execute_cmd(mtk_nor, MTK_NOR_PIO_READ_CMD);
    >>> if (ret < 0)
    >>> @@ -475,6 +481,11 @@ static int mtk_nor_drv_probe(struct platform_device *pdev)
    >>> if (IS_ERR(mtk_nor->base))
    >>> return PTR_ERR(mtk_nor->base);
    >>>
    >>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
    >>> + mtk_nor->flash_base = devm_ioremap_resource(&pdev->dev, res);
    >>
    >> There is a single API now: devm_platform_ioremap_resource().
    >
    > Cool. I'll change it.
    > Should I add another patch to change the same mapping operation right
    > above this piece of code?
    >

    That would be nice to do too, please send a separate patch.

    --
    Regards
    Vignesh

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