lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 7 Mar 2014 12:18:48 +0800
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Rob Herring <robherring2@...il.com>
CC:	Arnd Bergmann <arnd@...db.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Russell King <linux@....linux.org.uk>,
	Olof Johansson <olof@...om.net>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 3/7] of: introduce of_dma_is_coherent() helper

On Friday 07 March 2014 11:55 AM, Rob Herring wrote:
> On Thu, Mar 6, 2014 at 9:44 PM, Santosh Shilimkar
> <santosh.shilimkar@...com> wrote:
>> On Friday 07 March 2014 11:13 AM, Rob Herring wrote:
>>> On Thu, Mar 6, 2014 at 3:19 AM, Santosh Shilimkar
>>> <santosh.shilimkar@...com> wrote:
>>>> The of_dma_is_coherent() helper parses the given DT device
>>>> node to see if the "dma-coherent" property is supported and
>>>> returns true or false accordingly.
>>>>
>>>> For the architectures which are fully dma coherent and don't need per device
>>>> property, it can enable CONFIG_ARCH_IS_DMA_COHERENT config option which
>>>> enables DMA coherent for all devices by default.
>>>
>>> This worries me. I killed off arch_is_coherent() for arm. Now we're
>>> adding something back. Also, we already have HAVE_GENERIC_DMA_COHERENT
>>> which is different, but the names will be confusing. MIPS also has
>>> DMA_NONCOHERENT.
>>>
>> Thanks for comments Rob. I will address them in next version.
>> Specifically about ARCH_IS_DMA_COHERENT, I wasn't very comfortable either
>> while adding it. But as Arnd mentioned, there is a need to have a way
>> for the arch's which are fully coherent to use coherent ops by default.
>>
>> Am not sure whats the best way to have such support without imposing
>> any special updates on such arches.
> 
> Thinking about this some more, if the arch is always coherent or
> always non-coherent, then the default ops are always fine. In that
> case set_arch_dma_coherent_ops is always a nop and of_dma_is_coherent
> is a don't care.
> 
Hmmm.. I guess you are right. In that case we can drop the need of
config option.

Regards,
Santosh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists