[PATCH v5 2/6] uio: Add new UIO_MEM_PHYS_CACHE type for mem regions
From: gregkh@linuxfoundation.org (Greg Kroah-Hartman)
Date: 2014-11-27 02:41:40
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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?
quoted hunk ↗ jump to hunk
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 <redacted> Signed-off-by: Tushar Jagad <redacted> --- 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