linux-kernel - Re: [PATCH v2 1/3] firmware: Introduce request_firmware

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Date:	Mon, 11 Nov 2013 15:05:36 -0500
From:	Prarit Bhargava <prarit@...hat.com>
To:	Takashi Iwai <tiwai@...e.de>
CC:	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	Ming Lei <ming.lei@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org, amd64-microcode@...64.org
Subject: Re: [PATCH v2 1/3] firmware: Introduce request_firmware_direct()



On 11/11/2013 12:30 PM, Takashi Iwai wrote:
> At Mon, 11 Nov 2013 16:34:26 +0100,
> Borislav Petkov wrote:
>>
>> On Mon, Nov 11, 2013 at 04:21:16PM +0100, Takashi Iwai wrote:
>>> When CONFIG_FW_LOADER_USER_HELPER is set, request_firmware() falls
>>> back to the usermode helper for loading via udev when the direct
>>> loading fails.  But the recent udev takes way too long timeout (60
>>> seconds) for non-existing firmware.  This is unacceptable for the
>>> drivers like microcode loader where they load firmwares optionally,
>>> i.e. it's no error even if no requested file exists.
>>>
>>> This patch provides a new helper function, request_firmware_direct().
>>> It behaves as same as request_firmware() except for that it doesn't
>>> fall back to usermode helper but returns an error immediately if the
>>> f/w can't be loaded directly in kernel.
>>>
>>> Without CONFIG_FW_LOADER_USER_HELPER=y, request_firmware_direct() is
>>> just an alias of request_firmware(), due to obvious reason.
>>>
>>> Tested-by: Prarit Bhargava <prarit@...hat.com>
>>> Acked-by: Ming Lei <ming.lei@...onical.com>
>>> Signed-off-by: Takashi Iwai <tiwai@...e.de>
>>> ---
>>>  drivers/base/firmware_class.c | 36 +++++++++++++++++++++++++++++++-----
>>>  include/linux/firmware.h      |  7 +++++++
>>>  2 files changed, 38 insertions(+), 5 deletions(-)
>>
>> I like it, the 60 seconds thing has been a senseless PITA for no good
>> reason. I have always wondered what might change in 60 seconds wrt to us
>> being able to load the firmware...
>>
>>> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
>>> index eb8fb94ae2c5..7f48a6ffb0df 100644
>>> --- a/drivers/base/firmware_class.c
>>> +++ b/drivers/base/firmware_class.c
>>> @@ -1061,7 +1061,7 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device,
>>>  /* called from request_firmware() and request_firmware_work_func() */
>>>  static int
>>>  _request_firmware(const struct firmware **firmware_p, const char *name,
>>> -		  struct device *device, bool uevent, bool nowait)
>>> +		  struct device *device, bool uevent, bool nowait, bool fallback)
>>
>> Just a nitpick: three boolean args in a row starts to slowly look like a
>> function from the windoze API. Can we do:
>>
>> _request_firmware(..., unsigned long flags)
>>
>> instead and have nice bit flags for that?
> 
> Sounds like a good idea.  How about the patch below?
> (I used unsigned int since there shouldn't be so many different
>  behaviors.)
> 
> 
> thanks,
> 
> Takashi
> 
> ===
> 
> From: Takashi Iwai <tiwai@...e.de>
> Subject: [PATCH] firmware: Use bit flags instead of boolean combos
> 
> More than two boolean arguments to a function are rather confusing and
> error-prone for callers.  Let's make the behavior bit flags instead of
> triple combos.
> 
> A nice suggestion by Borislav Petkov.
> 
> Signed-off-by: Takashi Iwai <tiwai@...e.de>

Sure -- looks good.

Acked-by: Prarit Bhargava <prarit@...hat.com>

P.
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