Date:   Wed, 21 Mar 2018 17:33:17 +0100
From:   Robert Munteanu <rombert@...che.org>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>
Subject: Re: [PATCH v3] Fix modifier keys for Redragon Asura Keyboard

Hi Benjamin,

On Wed, 2018-03-21 at 17:12 +0100, Benjamin Tissoires wrote:
> Hi Robert,
> 
> First, apologies for not answering to the RFC. I missed it and it
> fell
> down in my INBOX.
> 
> On Wed, Mar 21, 2018 at 11:43 AM, Robert Munteanu <rombert@...che.org
> > wrote:
> > The microdia family of keyboards uses a non-standard way of sending
> > modifier keys.
> > 
> > The down event always sets the first bit to 0x04 and the second
> > keycode
> 
> Pretty sure you are talking about bytes here, not bits.
> And in the HID world, the first byte is usually a report ID.

Right, thanks for spotting that.

> 
> > to a custom value For instance, left shift sends the following bits
> > 
> >   04 02 00 00 00 00 00 00
> > 
> > while left control sends
> > 
> >   04 01 00 00 00 00 00 00
> 
> This sounds like bit(0) is mapped to LEFT_SHIFT and bit(1) mapped to
> LEFT_CONTROL in the second byte.
> Fortunately, LeftControl is designed in HID as 0xe0 in the keyboard
> HID usage table, and LeftShift is 0xe1. So that would match the
> behavior you are seeing.
> If you have 04 04 00 00 00 00 00 00 when pressing LeftAlt, then
> definitively you are just facing a bitmask, which is fairly common.
> 
> > 
> > As a result all modifier keys are mapped to left shift and the
> > keyboard is
> > non-functional in that respect. To solve the problem, we capture
> > the
> > raw data in raw_event and manually generate the correct input
> > events.
> 
> I'd like to see the hid-recorder events from these keypresses. The
> device might be buggy, but I have a gut feeling your solution is not
> the simplest one.
> Please grab hid-recorder from http://bentiss.github.io/hid-replay-
> docs/

See below, I recorded the output for pressing left ctrl, left alt, left
shift, right ctrl, right alt, right shift, meta.

D: 0
R: 169 05 0c 09 01 a1 01 85 01 19 00 2a 80 03 15 00 26 80 03 95 01 75
10 81 00 c0 05 01 09 80 a1 01 85 02 19 81 29 83 15 00 25 01 75 01 95 03
81 02 95 05 81 01 c0 06 00 ff 09 01 a1 01 85 03 1a f1 00 2a f8 00 15 00
25 01 75 01 95 08 81 02 c0 05 01 09 06 a1 01 85 04 05 07 19 e0 29 e7 15
00 25 01 75 01 95 08 81 00 95 30 75 01 15 00 25 01 05 07 19 00 29 2f 81
02 c0 05 01 09 06 a1 01 85 05 95 38 75 01 15 00 25 01 05 07 19 30 29 67
81 02 c0 05 01 09 06 a1 01 85 06 95 38 75 01 15 00 25 01 05 07 19 68 29
9f 81 02 c0
N: USB Keyboard
P: usb-0000:00:14.0-6/input1
I: 3 0c45 760b
D: 0
E: 0.000000 8 04 01 00 00 00 00 00 00
E: 0.039920 8 04 00 00 00 00 00 00 00
E: 0.751952 8 04 04 00 00 00 00 00 00
E: 0.823977 8 04 00 00 00 00 00 00 00
E: 2.639887 8 04 02 00 00 00 00 00 00
E: 2.711896 8 04 00 00 00 00 00 00 00
E: 3.583932 8 04 10 00 00 00 00 00 00
E: 3.663919 8 04 00 00 00 00 00 00 00
E: 4.871886 8 04 40 00 00 00 00 00 00
E: 4.935906 8 04 00 00 00 00 00 00 00
E: 6.503872 8 04 20 00 00 00 00 00 00
E: 6.575850 8 04 00 00 00 00 00 00 00
E: 7.383844 8 04 08 00 00 00 00 00 00
E: 7.455861 8 04 00 00 00 00 00 00 00

> 
> > 
> > The keyboard functions mostly as expected now, with only a few
> > minor
> > issues:
> > 
> > - two USB devices are detected instead of 1
> 
> Well, that should be easy enough to solve

I think so, but I could not find a way how to do that.

> 
> > - some key combinations are not triggered - e.g.
> >   left shift + left ctrl + p. However, the same combination is
> > recognized
> >   with the right shift key.
> 
> Could you add this combination in the hid-recorder output too?

This is what Left Ctrl + Shift + U produces:

E: 24.575686 8 04 01 00 00 00 00 00 00
E: 24.951689 8 04 03 00 00 00 00 00 00
E: 26.719615 8 04 01 00 00 00 00 00 00
E: 26.727611 8 04 00 00 00 00 00 00 00

On the other hand, Right Ctrl + Shift + U produces:

E: 55.911268 8 04 10 00 00 00 00 00 00
E: 56.119280 8 04 30 00 00 00 00 00 00
E: 56.599319 8 04 30 00 00 00 01 00 00
E: 56.703282 8 04 30 00 00 00 00 00 00
E: 56.815278 8 04 20 00 00 00 00 00 00
E: 56.823255 8 04 00 00 00 00 00 00 00

It looks suspicious that the keypress is not registered. Do I need to
boot a kernel without my patch applied?

> more comments inlined:
> 
> > 
> > Changelog:
> > 
> > - v2: modifier keys work, some combinations are still troublesome
> > - v3: style cleanup, rebase on top of 4.14
> > - v4: remove most debugging calls, make init info useful for user,
> >   rebased on top of 4.15
> > 
> > Signed-off-by: Robert Munteanu <rombert@...che.org>
> > ---
> >  drivers/hid/Kconfig        |   9 +++
> >  drivers/hid/Makefile       |   2 +-
> >  drivers/hid/hid-core.c     |   3 +
> >  drivers/hid/hid-ids.h      |   3 +
> >  drivers/hid/hid-microdia.c | 148
> > +++++++++++++++++++++++++++++++++++++++++++++
> >  5 files changed, 164 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/hid/hid-microdia.c
> > 
> > diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> > index 779c5ae47f36..c3350f2ec4ea 100644
> > --- a/drivers/hid/Kconfig
> > +++ b/drivers/hid/Kconfig
> > @@ -548,6 +548,15 @@ config HID_MAYFLASH
> >         Say Y here if you have HJZ Mayflash PS3 game controller
> > adapters
> >         and want to enable force feedback support.
> > 
> > +config HID_MICRODIA
> > +       tristate "Microdia based keyboards"
> > +       depends on HID
> > +       default !EXPERT
> > +       ---help---
> > +    Support for Microdia devices that are not compliant with the
> > HID standard.
> > +
> > +    One known example if the Redragon Asura Keyboard.
> > +
> >  config HID_MICROSOFT
> >         tristate "Microsoft non-fully HID-compliant devices"
> >         depends on HID
> > diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> > index 235bd2a7b333..e66a305876c5 100644
> > --- a/drivers/hid/Makefile
> > +++ b/drivers/hid/Makefile
> > @@ -62,6 +62,7 @@ obj-$(CONFIG_HID_LOGITECH_DJ) += hid-logitech-
> > dj.o
> >  obj-$(CONFIG_HID_LOGITECH_HIDPP)       += hid-logitech-hidpp.o
> >  obj-$(CONFIG_HID_MAGICMOUSE)   += hid-magicmouse.o
> >  obj-$(CONFIG_HID_MAYFLASH)     += hid-mf.o
> > +obj-$(CONFIG_HID_MICRODIA)  += hid-microdia.o
> >  obj-$(CONFIG_HID_MICROSOFT)    += hid-microsoft.o
> >  obj-$(CONFIG_HID_MONTEREY)     += hid-monterey.o
> >  obj-$(CONFIG_HID_MULTITOUCH)   += hid-multitouch.o
> > @@ -121,4 +122,3 @@ obj-$(CONFIG_USB_KBD)               += usbhid/
> > 
> >  obj-$(CONFIG_I2C_HID)          += i2c-hid/
> > 
> > -obj-$(CONFIG_INTEL_ISH_HID)    += intel-ish-hid/
> > diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> > index 0c3f608131cf..b36c2df4b755 100644
> > --- a/drivers/hid/hid-core.c
> > +++ b/drivers/hid/hid-core.c
> > @@ -2393,6 +2393,9 @@ static const struct hid_device_id
> > hid_have_special_driver[] = {
> >  #endif
> >  #if IS_ENABLED(CONFIG_HID_ZYDACRON)
> >         { HID_USB_DEVICE(USB_VENDOR_ID_ZYDACRON,
> > USB_DEVICE_ID_ZYDACRON_REMOTE_CONTROL) },
> > +#endif
> > +#if IS_ENABLED(CONFIG_HID_MICRODIA)
> > +       {
> > HID_USB_DEVICE(USB_VENDOR_ID_MICRODIA,  USB_DEVICE_ID_REDRAGON_ASUR
> > A) },
> >  #endif
> 
> You don't need this hunk anymore since v4.15 IIRC

Ack, will update and retest.

> 
> >         { }
> >  };
> > diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> > index 5da3d6256d25..146869e55c5a 100644
> > --- a/drivers/hid/hid-ids.h
> > +++ b/drivers/hid/hid-ids.h
> > @@ -1171,4 +1171,7 @@
> >  #define USB_VENDOR_ID_UGTIZER                  0x2179
> >  #define USB_DEVICE_ID_UGTIZER_TABLET_GP0610    0x0053
> > 
> > +#define USB_VENDOR_ID_MICRODIA          0x0c45
> > +#define USB_DEVICE_ID_REDRAGON_ASURA    0x760b
> > +
> >  #endif
> > diff --git a/drivers/hid/hid-microdia.c b/drivers/hid/hid-
> > microdia.c
> > new file mode 100644
> > index 000000000000..f9d8de18a989
> > --- /dev/null
> > +++ b/drivers/hid/hid-microdia.c
> > @@ -0,0 +1,148 @@
> 
> missing the SPDX identifier
> (see Documentation/process/license-rules.rst)

Ack, will update.

> 
> > +/*
> > + *  HID driver for Microdia-based keyboards
> > + *
> > + *  Copyright (c) 2017 Robert Munteanu
> > + */
> > +
> > +/*
> > + * This program is free software; you can redistribute it and/or
> > modify it
> > + * under the terms of the GNU General Public License as published
> > by the Free
> > + * Software Foundation; either version 2 of the License, or (at
> > your option)
> > + * any later version.
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/input.h>
> > +#include <linux/hid.h>
> > +#include <linux/module.h>
> > +#include <linux/log2.h>
> > +#include <linux/input-event-codes.h>
> > +
> > +#include "hid-ids.h"
> > +
> > +
> > +// The microdia family of keyboards uses a non-standard way of
> > sending
> > +// modifier keys
> 
> Unless it has changed since last time I checked, we do not use C++
> comments
> (see Documentation/process/coding-style.rst)

Ack.

> 
> > +//
> > +// The down event always sets the first bit to 0x04 and the second
> > keycode
> > +// to a custom value. For instance, left shift sends the following
> > bits
> > +//
> > +//   04 02 00 00 00 00 00 00
> > +//
> > +// while left control sends
> > +//
> > +//   04 01 00 00 00 00 00 00
> > +//
> > +// Unfortunately these are all mapped to left shift and the
> > keyboard is
> > +// non-functional in that respect. To solve the problem, we
> > capture the
> > +// raw data in raw_event and manually generate the correct input
> > events
> > +//
> > +// TODO
> > +//
> > +// 1. Some modifiers keys still don't work, e.g. Ctrl-Shift-P
> > +//    Interestingly enough, this happens when pressing the
> > physical
> > +//    left shift key, but now when pressing the physical right
> > shift key.
> > +//    hexdump does not show them either.
> > +// 2. A second USB keyboard is registered, but it should be
> > removed
> > +// 3. Modifier keys sometimes get stuck, need to re-press to clear
> > +
> > +static int microdia_input_configured(struct hid_device *hdev,
> > +       struct hid_input *hi)
> > +{
> > +
> > +       hid_info(hdev, "Keyboard configured with limited support
> > (modifier keys may get stuck, some modifiers combinations with
> > left-shift not working) ");
> > +
> > +       hid_set_drvdata(hdev, hi);
> > +
> > +       return 0;
> > +}
> > +
> > +static int microdia_input_mapping(struct hid_device *hdev, struct
> > hid_input *hi,
> > +               struct hid_field *field, struct hid_usage *usage,
> > +               unsigned long **bit, int *max)
> > +{
> > +       // do not map left shift since we will manually generate
> > input
> > +       // events in microdia_raw_event
> > +       if ((usage->hid & HID_USAGE_PAGE) == HID_UP_KEYBOARD)
> > +               if ((usage->hid & HID_USAGE) == 0xe1)
> > +                       return -1;
> > +
> > +       return 0;
> > +}
> > +
> > +// array index of a modifier matches the bit index in the data
> > payload
> > +// the modifier data is always stored in the second int
> > +// e.g. for left alt the 1 bit is set - 04 04 ...
> > +// TODO - second entry should be left shift, but that's not
> > possible
> > +// since we ignore it in the mapping
> > +static int microdia_modifiers[7] = {
> > +               KEY_LEFTCTRL,
> > +               KEY_RIGHTSHIFT,
> > +               KEY_LEFTALT,
> > +               KEY_LEFTMETA,
> > +               KEY_RIGHTCTRL,
> > +               KEY_RIGHTSHIFT,
> > +               KEY_RIGHTALT
> > +};
> > +
> > +static int microdia_last_handled_modifier;
> > +
> > +static int microdia_raw_event(struct hid_device *hdev,
> > +               struct hid_report *report, u8 *data, int size)
> > +{
> > +       int i, changed_key, new_value, mapped_key;
> > +       struct hid_input *hi;
> > +
> > +       // 1. validate that we get 8 bits of the for 04 xx 00 00 00
> > 00 00 00
> > +       if (size != 8)
> > +               return 0;
> > +
> > +       if (data[0] != 4)
> > +               return 0;
> > +
> > +       // TODO - can I somehow use a bit mask? data & 0x00ffffff
> > != 0
> > +       for (i = 2; i < size; i++)
> > +               if (data[i] != 0)
> > +                       return 0;
> > +
> > +       // TODO - don't process the keyup event 04 00 00 00 00 00
> > 00 00
> 
> That's a lot of TODO in such a simple driver :/

Yes, well that's what I get for learning to write hid drivers by
example ... and C isn't my primary programming language either.

> 
> > +       // if we don't expect a modifier key 'up' event
> > +
> > +       // 2. detect based on previous data what key was pressed or
> > depressed
> > +       // a key was pressed or depressed if its bit has a
> > different value
> > +       // between this and the previous invocation. If the bit is
> > set
> > +       // it was pressed
> > +
> > +       changed_key = data[1] ^ microdia_last_handled_modifier;
> > +       new_value = (data[1] & changed_key) != 0;
> > +       // TODO - is ilog2 really needed?
> > +       mapped_key = microdia_modifiers[ilog2(changed_key)];
> 
> What if you get 2 changed keys at a time?

This could explain the problems that I've been getting with modifier
keys being 'stuck'.

> 
> Anyway, before giving you a ACK or NACK on the driver, the behavior
> from the keyboard firmware looks sane and pretty common. So my guess
> is that there is something wrong in the report descriptors, and I
> need
> the hid-recorder output to have a better idea of what is wrong with
> our current handling of this keyboard.

The output is inline. That being said, I'm aware that re-firing the
keypress events myself does not belong in a HID driver, but I'm eager
to work on this being massaged into something proper for inclusion.

Thanks for taking the time to review.

Robert

> 
> Cheers,
> Benjamin
> 
> > +
> > +       // 3. report the key event and track what was sent
> > +       hi = hid_get_drvdata(hdev);
> > +
> > +       input_report_key(hi->input, mapped_key, new_value);
> > +
> > +       microdia_last_handled_modifier = data[1];
> > +
> > +       return 1;
> > +}
> > +
> > +static const struct hid_device_id microdia_devices[] = {
> > +       {HID_USB_DEVICE(USB_VENDOR_ID_MICRODIA,
> > USB_DEVICE_ID_REDRAGON_ASURA)},
> > +       {}
> > +};
> > +
> > +MODULE_DEVICE_TABLE(hid, microdia_devices);
> > +
> > +static struct hid_driver microdia_driver = {
> > +       .name = "microdia",
> > +       .input_mapping = microdia_input_mapping,
> > +       .id_table = microdia_devices,
> > +       .raw_event = microdia_raw_event,
> > +       .input_configured = microdia_input_configured,
> > +};
> > +
> > +module_hid_driver(microdia_driver);
> > +
> > +MODULE_LICENSE("GPL");
> > --
> > 2.16.2
> > 

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