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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Ankit Jindal <ankit.jindal@linaro.org>
Cc: linux-kernel@vger.kernel.org, "Hans J. Koch" <hjk@hansjkoch.de>,
	patches@apm.com, linux-arm-kernel@lists.infradead.org,
	"Rob Herring" <robh+dt@kernel.org>,
	"Tushar Jagad" <tushar.jagad@linaro.org>,
	"Russell King - ARM Linux" <linux@arm.linux.org.uk>,
	devicetree@vger.kernel.org, "Guenter Roeck" <linux@roeck-us.net>,
	"Varka Bhadram" <varkabhadram@gmail.com>,
	"Kumar Gala" <galak@codeaurora.org>,
	"Anup Patel" <anup@brainfault.org>,
	"Andreas Färber" <afaerber@suse.de>
Subject: Re: [PATCH v5 2/6] uio: Add new UIO_MEM_PHYS_CACHE type for mem regions
Date: Wed, 26 Nov 2014 16:01:47 -0800	[thread overview]
Message-ID: <20141127000147.GC5313@kroah.com> (raw)
In-Reply-To: <1416220572-13381-3-git-send-email-ankit.jindal@linaro.org>

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

  reply	other threads:[~2014-11-27  2:41 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-17 10:36 [PATCH v5 0/6] UIO driver for APM X-Gene QMTM Ankit Jindal
2014-11-17 10:36 ` [PATCH v5 1/6] uio: code style cleanup Ankit Jindal
2014-11-17 10:36 ` [PATCH v5 2/6] uio: Add new UIO_MEM_PHYS_CACHE type for mem regions Ankit Jindal
2014-11-27  0:01   ` Greg Kroah-Hartman [this message]
2014-12-08 12:43     ` Ankit Jindal
2014-11-17 10:36 ` [PATCH v5 3/6] Documentation: Update documentation for UIO_MEM_PHYS_CACHE Ankit Jindal
2014-11-17 10:36 ` [PATCH v5 4/6] uio: Add X-Gene QMTM UIO driver Ankit Jindal
2014-11-17 10:36 ` [PATCH v5 5/6] Documentation: dt-bindings: Add binding info for " Ankit Jindal
2014-11-17 10:43   ` Andreas Färber
2014-11-17 11:17   ` Arnd Bergmann
2014-11-18  9:29     ` Ankit Jindal
2014-11-18 13:10       ` Arnd Bergmann
2014-12-08 12:42         ` Ankit Jindal
2014-12-08 17:15           ` Rob Herring
2014-12-09  6:33             ` Ankit Jindal
2014-11-17 10:36 ` [PATCH v5 6/6] MAINTAINERS: Add entry for APM " Ankit Jindal

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