linux-kernel - Re: [RFC v0 7/8] Input: ims-pcu: use firmware

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Date:	Sun, 31 Jul 2016 00:23:09 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	"Luis R. Rodriguez" <mcgrof@...nel.org>,
	Arend van Spriel <arend.vanspriel@...adcom.com>
CC:	Daniel Wagner <daniel.wagner@...-carit.de>,
	Bjorn Andersson <bjorn.andersson@...aro.org>,
	Daniel Wagner <wagi@...om.org>,
	Bastien Nocera <hadess@...ess.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Johannes Berg <johannes.berg@...el.com>,
	Kalle Valo <kvalo@...eaurora.org>,
	Ohad Ben-Cohen <ohad@...ery.com>, linux-input@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC v0 7/8] Input: ims-pcu: use firmware_stat instead of completion

On July 30, 2016 9:58:17 AM PDT, "Luis R. Rodriguez" <mcgrof@...nel.org> wrote:
>On Sat, Jul 30, 2016 at 02:42:41PM +0200, Arend van Spriel wrote:
>> + Luis (again) ;-)
>> 
>> On 29-07-16 08:13, Daniel Wagner wrote:
>> > On 07/28/2016 09:01 PM, Bjorn Andersson wrote:
>> >> On Thu 28 Jul 11:33 PDT 2016, Dmitry Torokhov wrote:
>> >>
>> >>> On Thu, Jul 28, 2016 at 09:55:11AM +0200, Daniel Wagner wrote:
>> >>>> From: Daniel Wagner <daniel.wagner@...-carit.de>
>> >>>>
>> >> [..]
>> >>>
>> >>> Do not quite like it... I'd rather asynchronous request give out
>a
>> >>> firmware status pointer that could be used later on.
>> 
>> Excellent. Why not get rid of the callback function as well and have
>> fw_loading_wait() return result (0 = firmware available, < 0 = fail).
>> Just to confirm, you are proposing a new API function next to
>> request_firmware_nowait(), right?
>
>If proposing new firmware_class patches please bounce / Cc me, I've
>recently asked for me to be added to MAINTAINERS so I get these
>e-mails as I'm working on a new flexible API which would allow us
>to extend the firmware API without having to care about the old
>stupid usermode helper at all.

I am not sure why we started calling usermode helper "stupid". We only had to implement direct kernel firmware loading because udev/stsremd folks had "interesting" ideas how events should be handled; but having userspace to feed us data is not stupid.

If we want to overhaul firmware loading support we need to figure out how to support case when a driver want to [asynchronously] request firmware/config/blob and the rest of the system is not ready. Even if we want kernel to do read/load the data we need userspace to tell kernel when firmware partition is available, until then the kernel should not fail the request.


Thanks.

-- 
Dmitry