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SubjectRe: [PATCH 1/3] mtd: spi-nor: add optional DMA-safe bounce buffer for data transfer
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Hi Cyrille,

Thanks for doing this series! One comment below.

On 24-Dec-17 10:06 AM, Cyrille Pitchen wrote:
[...]
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 8bafd462f0ae..59f9fbd45234 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -14,8 +14,10 @@
> #include <linux/errno.h>
> #include <linux/module.h>
> #include <linux/device.h>
> +#include <linux/highmem.h>
> #include <linux/mutex.h>
> #include <linux/math64.h>
> +#include <linux/mm.h>
> #include <linux/sizes.h>
> #include <linux/slab.h>
>
> @@ -1232,6 +1234,56 @@ static const struct flash_info spi_nor_ids[] = {
> { },
> };
>
> +static bool spi_nor_is_dma_safe(const void *buf)
> +{
> + if (is_vmalloc_addr(buf))
> + return false;
> +
> +#ifdef CONFIG_HIGHMEM
> + if ((unsigned long)buf >= PKMAP_BASE &&
> + (unsigned long)buf < (PKMAP_BASE + (LAST_PKMAP * PAGE_SIZE)))
> + return false;
> +#endif
> +
> + return true;
> +}
> +

Better way would be to use virt_addr_valid():
static bool spi_nor_is_dma_safe(const void *buf)
{
return virt_addr_valid(buf);
}

Regards
Vignesh

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