Re: [PATCH] usb: gadget: f_hid: added GET_IDLE and SET_IDLE handlers

From: Felipe Balbi <balbi@kernel.org>
To: Maxim Devaev <mdevaev@gmail.com>
Cc: gregkh@linuxfoundation.org, sandeen@redhat.com,
	linux-usb@vger.kernel.org, mdevaev@gmail.com
Subject: Re: [PATCH] usb: gadget: f_hid: added GET_IDLE and SET_IDLE handlers
Date: Fri, 23 Jul 2021 10:20:29 +0300	[thread overview]
Message-ID: <87sg05lcn6.fsf@kernel.org> (raw)
In-Reply-To: <20210722205132.7a168041@reki>

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Maxim Devaev <mdevaev@gmail.com> writes:

>> Felipe Balbi <balbi@kernel.org> writes:
>> 
>> yeah, I don't see any issues with this. If you have access to the tool,
>> mind running USBCV on the f_hid gadget? Would be cool to get some
>> confirmation that we're within spec.
>
> Thanks for pointing to USBCV. I used a hardware USB protocol analyzer
> to understand what was wrong with f_hid, and my hosts only sent idle=0.
> Thanks to the test, I realized that I should only use the upper byte
> that contains duration. Here a fixed version of the patch,
> which successfully passes all HID tests. The idle part:
>
>     Now Starting Test: HID Class GET/SET Idle Test (Configuration Index 0)
>     Start time: Jul 22, 2021 - 20:29:40
>     No report IDs found in report descriptor for Interface : 0x0
>     GET/SETIdle test for report ID 0. Setting Idle rate to : 0x7F
>     No report IDs found in report descriptor for Interface : 0x1
>     GET/SETIdle test for report ID 0. Setting Idle rate to : 0x7F
>     
>     Stop time: Jul 22, 2021 - 20:29:41
>     Duration:  1 second.
>     Stopping Test [ HID Class GET/SET Idle Test (Configuration Index 0):
>          Number of: Fails (0); Aborts (0); Warnings (0) ]
>
>
> From ac56ddc1ab2dfa599a12a3bf064e520d587e89fe Mon Sep 17 00:00:00 2001
> From: Maxim Devaev <mdevaev@gmail.com>
> Date: Wed, 21 Jul 2021 20:48:28 +0300
> Subject: [PATCH] usb: gadget: f_hid: added GET_IDLE and SET_IDLE handlers
>
> The USB HID standard declares mandatory support for GET_IDLE and SET_IDLE
> requests for Boot Keyboard. Most hosts can handle their absence, but others
> like some old/strange UEFIs and BIOSes consider this a critical error
> and refuse to work with f_hid.
>
> This primitive implementation of saving and returning idle is sufficient
> to meet the requirements of the standard and these devices.
>
> Signed-off-by: Maxim Devaev <mdevaev@gmail.com>

Great, thank you.

Acked-by: Felipe Balbi <balbi@kernel.org>

-- 
balbi

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