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References: <4AFD971C.3090204@csldevices.co.uk>
	 <4AFD9BAF.1010200@csldevices.co.uk>
	 <aday6mac5ai.fsf@roland-alpha.cisco.com> <4AFED614.1050109@gmail.com>
	 <53ea87da0911140855u7993989aod746bcaf18ee4c31@mail.gmail.com>
Date: Sat, 14 Nov 2009 12:19:13 -0600
Message-ID: <51f3faa70911141019y1248fb27k5f7edb3729f72375@mail.gmail.com>
Subject: Re: firmware loading interface
From: Robert Hancock <hancockrwd@gmail.com>
To: venu <vjosyula@gmail.com>
Cc: Roland Dreier <rdreier@cisco.com>, Philip Downer <phil@csldevices.co.uk>,
       linux-kernel@vger.kernel.org
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On Sat, Nov 14, 2009 at 10:55 AM, venu <vjosyula@gmail.com> wrote:
> ?who triggers this upgrade from userspace ? I understand it is a naivee /
> beginers questions but i hope somebody explains me how ?

The request_firmware interface probably isn't suitable for that..
using an ioctl or read/write-based interface, possibly on a separate
device node, would likely be the way to go..

>
> On Sat, Nov 14, 2009 at 9:38 PM, Robert Hancoctk <hancockrwd@gmail.cr tom>
> wrote:
>>
>> On 11/13/2009 06:35 PM, Roland Dreier wrote:
>>>
>>> ?> ?However our device will have flash to store the firmware in and,
>>> whilst
>>> ?> ?it looks as though it would be possible for us to use
>>> request_firmware
>>> ?> ?to provide occasional firmware upgrades from userspace, I can't find
>>> any
>>> ?> ?reference as to whether this is an accepted method for doing so.
>>> Could
>>> ?> ?someone please confirm for me whether or not it's a good idea to use
>>> ?> ?request_firmware for this, or perhaps point me at another standard
>>> ?> ?method for doing firmware updates from userspace?
>>>
>>> I think request_firmware() is fine for this... you could have a look at
>>> drivers/net/cxgb3 to see a device that writes new firmware to flash when
>>> it detects a version mismatch between driver and device.
>>
>> It depends on the consequences of a failed flash due to losing power,
>> crash, etc - if it has the potential to brick the device then I don't think
>> that should happen without the user triggering it explicitly..
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