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SubjectRe: [PATCH] mtd: orion-nand: fix build error with ARMv4
On Fri, 21 Jul 2017 22:38:06 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> orion_nand_read_buf uses an inline assembly with the "ldrd"
> instruction, which is only available from ARMv5 upwards. This
> used to be fine, since all users have an ARMv5 or ARMv7 CPU,
> but now we can also build a multiplatform kernel with ARMv4
> support enabled in addition to the "kirkwood" (mvebu) platform.
>
> This provides an alternative to call the readsl() function that
> is supposed to have the same effect and is also optimized for
> performance.
>
> I first posted a version of this patch back in 2014, and there
> was some discussion about it then. This fixes the bugs identified
> back then and should be a reasonable alternative for the rare
> corner case.

Looks good to me. Applied to nand/next. Let's see if anyone complains
before the merge window.

Thanks,

Boris

>
> Link: https://patchwork.kernel.org/patch/4144791/
> Cc: Jingoo Han <jg1.han@samsung.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/mtd/nand/orion_nand.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/mtd/nand/orion_nand.c b/drivers/mtd/nand/orion_nand.c
> index 209170ed2b76..41cb7acfc044 100644
> --- a/drivers/mtd/nand/orion_nand.c
> +++ b/drivers/mtd/nand/orion_nand.c
> @@ -54,13 +54,16 @@ static void orion_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
> {
> struct nand_chip *chip = mtd_to_nand(mtd);
> void __iomem *io_base = chip->IO_ADDR_R;
> +#if __LINUX_ARM_ARCH__ >= 5
> uint64_t *buf64;
> +#endif
> int i = 0;
>
> while (len && (unsigned long)buf & 7) {
> *buf++ = readb(io_base);
> len--;
> }
> +#if __LINUX_ARM_ARCH__ >= 5
> buf64 = (uint64_t *)buf;
> while (i < len/8) {
> /*
> @@ -74,6 +77,10 @@ static void orion_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
> buf64[i++] = x;
> }
> i *= 8;
> +#else
> + readsl(io_base, buf, len/4);
> + i = len / 4 * 4;
> +#endif
> while (i < len)
> buf[i++] = readb(io_base);
> }

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