On Mon, Nov 17, 2014 at 04:06:08PM +0530, Ankit Jindal wrote:
> Currently, three types of mem regions are supported: UIO_MEM_PHYS,
> UIO_MEM_LOGICAL and UIO_MEM_VIRTUAL. Among these UIO_MEM_PHYS helps
> UIO driver export physcial memory to user space as non-cacheable
> user memory. Typcially memory-mapped registers of a device are exported
> to user space as UIO_MEM_PHYS type mem region. The UIO_MEM_PHYS type
> is not efficient if dma-capable devices are capable of maintaining coherency
> with CPU caches.
Not efficient in what way?
> This patch adds new type UIO_MEM_PHYS_CACHE for mem regions to enable
> cacheable access to physical memory from user space.
>
> Signed-off-by: Ankit Jindal <ankit.jin...@linaro.org>
> Signed-off-by: Tushar Jagad <tushar.ja...@linaro.org>
> ---
> drivers/uio/uio.c | 11 ++++++++---
> include/linux/uio_driver.h | 1 +
> 2 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 97e6444..120a84b 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -644,7 +644,7 @@ static const struct vm_operations_struct
> uio_physical_vm_ops = {
> #endif
> };
>
> -static int uio_mmap_physical(struct vm_area_struct *vma)
> +static int uio_mmap_physical(struct vm_area_struct *vma, bool cacheable)
I despise "bool" flags in a function, as they don't give any idea of
what is going on when you see the function being called. Please create
a new function that does this properly, with a correct name, if it's
needed.
thanks,
greg k-h
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
