Messages in this thread | | | Date | Wed, 26 Nov 2014 16:01:47 -0800 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH v5 2/6] uio: Add new UIO_MEM_PHYS_CACHE type for mem regions |
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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?
> 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.jindal@linaro.org> > Signed-off-by: Tushar Jagad <tushar.jagad@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
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