Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-06-19 Thread Wei Ni
> Atomic operations are undefined behavior on ARM for device or strongly > ordered memory types. So use write-combine variants for mappings. This > corresponds to normal, non-cacheable memory on ARM. For many other > architectures, this change should not change the mapping type. Hi, all I have

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-06-19 Thread Wei Ni
Atomic operations are undefined behavior on ARM for device or strongly ordered memory types. So use write-combine variants for mappings. This corresponds to normal, non-cacheable memory on ARM. For many other architectures, this change should not change the mapping type. Hi, all I have met

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-19 Thread Russell King - ARM Linux
On Tue, Apr 09, 2013 at 08:53:18PM -0700, Colin Cross wrote: > On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring wrote: > > - return ioremap(start, size); > > + return ioremap_wc(start, size); > > ioremap_wc corresponds to MT_DEVICE_WC, which is still device memory, > so I don't see how

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-19 Thread Russell King - ARM Linux
On Tue, Apr 09, 2013 at 08:53:18PM -0700, Colin Cross wrote: On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring robherri...@gmail.com wrote: - return ioremap(start, size); + return ioremap_wc(start, size); ioremap_wc corresponds to MT_DEVICE_WC, which is still device memory, so I

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-16 Thread Catalin Marinas
On Tue, Apr 16, 2013 at 01:58:27PM +0100, Rob Herring wrote: > On 04/16/2013 03:44 AM, Will Deacon wrote: > > On Tue, Apr 16, 2013 at 01:43:09AM +0100, Colin Cross wrote: > >> On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring wrote: > >>> Exclusive accesses still have further restrictions. From

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-16 Thread Rob Herring
On 04/16/2013 03:44 AM, Will Deacon wrote: > On Tue, Apr 16, 2013 at 01:43:09AM +0100, Colin Cross wrote: >> On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring wrote: >>> Exclusive accesses still have further restrictions. From section 3.4.5: >>> >>> • It is IMPLEMENTATION DEFINED whether LDREX and

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-16 Thread Will Deacon
On Tue, Apr 16, 2013 at 01:43:09AM +0100, Colin Cross wrote: > On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring wrote: > > Exclusive accesses still have further restrictions. From section 3.4.5: > > > > • It is IMPLEMENTATION DEFINED whether LDREX and STREX operations can be > > performed to a memory

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-16 Thread Will Deacon
On Tue, Apr 16, 2013 at 01:43:09AM +0100, Colin Cross wrote: On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring robherri...@gmail.com wrote: Exclusive accesses still have further restrictions. From section 3.4.5: • It is IMPLEMENTATION DEFINED whether LDREX and STREX operations can be performed

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-16 Thread Rob Herring
On 04/16/2013 03:44 AM, Will Deacon wrote: On Tue, Apr 16, 2013 at 01:43:09AM +0100, Colin Cross wrote: On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring robherri...@gmail.com wrote: Exclusive accesses still have further restrictions. From section 3.4.5: • It is IMPLEMENTATION DEFINED whether

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-16 Thread Catalin Marinas
On Tue, Apr 16, 2013 at 01:58:27PM +0100, Rob Herring wrote: On 04/16/2013 03:44 AM, Will Deacon wrote: On Tue, Apr 16, 2013 at 01:43:09AM +0100, Colin Cross wrote: On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring robherri...@gmail.com wrote: Exclusive accesses still have further restrictions.

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-15 Thread Colin Cross
On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring wrote: > On 04/15/2013 05:21 PM, Colin Cross wrote: >> On Wed, Apr 10, 2013 at 6:30 AM, Rob Herring wrote: >>> On 04/09/2013 10:53 PM, Colin Cross wrote: On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring wrote: > From: Rob Herring > >

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-15 Thread Rob Herring
On 04/15/2013 05:21 PM, Colin Cross wrote: > On Wed, Apr 10, 2013 at 6:30 AM, Rob Herring wrote: >> On 04/09/2013 10:53 PM, Colin Cross wrote: >>> On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring wrote: From: Rob Herring Atomic operations are undefined behavior on ARM for device or

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-15 Thread Colin Cross
On Wed, Apr 10, 2013 at 6:30 AM, Rob Herring wrote: > On 04/09/2013 10:53 PM, Colin Cross wrote: >> On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring wrote: >>> From: Rob Herring >>> >>> Atomic operations are undefined behavior on ARM for device or strongly >>> ordered memory types. So use

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-15 Thread Colin Cross
On Wed, Apr 10, 2013 at 6:30 AM, Rob Herring robherri...@gmail.com wrote: On 04/09/2013 10:53 PM, Colin Cross wrote: On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring robherri...@gmail.com wrote: From: Rob Herring rob.herr...@calxeda.com Atomic operations are undefined behavior on ARM for device or

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-15 Thread Rob Herring
On 04/15/2013 05:21 PM, Colin Cross wrote: On Wed, Apr 10, 2013 at 6:30 AM, Rob Herring robherri...@gmail.com wrote: On 04/09/2013 10:53 PM, Colin Cross wrote: On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring robherri...@gmail.com wrote: From: Rob Herring rob.herr...@calxeda.com Atomic operations

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-15 Thread Colin Cross
On Mon, Apr 15, 2013 at 4:59 PM, Rob Herring robherri...@gmail.com wrote: On 04/15/2013 05:21 PM, Colin Cross wrote: On Wed, Apr 10, 2013 at 6:30 AM, Rob Herring robherri...@gmail.com wrote: On 04/09/2013 10:53 PM, Colin Cross wrote: On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-10 Thread Rob Herring
On 04/09/2013 10:53 PM, Colin Cross wrote: > On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring wrote: >> From: Rob Herring >> >> Atomic operations are undefined behavior on ARM for device or strongly >> ordered memory types. So use write-combine variants for mappings. This >> corresponds to normal,

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-10 Thread Rob Herring
On 04/09/2013 10:53 PM, Colin Cross wrote: On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring robherri...@gmail.com wrote: From: Rob Herring rob.herr...@calxeda.com Atomic operations are undefined behavior on ARM for device or strongly ordered memory types. So use write-combine variants for

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-09 Thread Colin Cross
On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring wrote: > From: Rob Herring > > Atomic operations are undefined behavior on ARM for device or strongly > ordered memory types. So use write-combine variants for mappings. This > corresponds to normal, non-cacheable memory on ARM. For many other >

[RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-09 Thread Rob Herring
From: Rob Herring Atomic operations are undefined behavior on ARM for device or strongly ordered memory types. So use write-combine variants for mappings. This corresponds to normal, non-cacheable memory on ARM. For many other architectures, this change should not change the mapping type.

[RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-09 Thread Rob Herring
From: Rob Herring rob.herr...@calxeda.com Atomic operations are undefined behavior on ARM for device or strongly ordered memory types. So use write-combine variants for mappings. This corresponds to normal, non-cacheable memory on ARM. For many other architectures, this change should not change

Re: [RFC PATCH 1/3] pstore-ram: use write-combine mappings

2013-04-09 Thread Colin Cross
On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring robherri...@gmail.com wrote: From: Rob Herring rob.herr...@calxeda.com Atomic operations are undefined behavior on ARM for device or strongly ordered memory types. So use write-combine variants for mappings. This corresponds to normal, non-cacheable