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From:   Benjamin Tissoires <benjamin.tissoires@redhat.com>
Date:   Mon, 16 Apr 2018 12:02:01 +0200
Message-ID: <CAO-hwJKbYyZdtq=zg_ZeJOiL=5cTbD4oKuWmpF-P_7TgBkqVYA@mail.gmail.com>
Subject: Re: [PATCH v5] Fix modifier keys for Redragon Asura Keyboard
To:     Robert Munteanu <rombert@apache.org>
Cc:     Jiri Kosina <jikos@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Robert,

On Wed, Apr 11, 2018 at 11:49 AM, Robert Munteanu <rombert@apache.org> wrote:
> 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
> - v5: fix the HID descriptor as suggested by Benjamin Tissoires,
>   use existing USB vendor id, update comment style, add SPDX
>   license identifier, rename to hid-redragon, stop registering
>   two input devices, rebased on top of 4.16

As Jiri said, please provide a correct commit message.

I have a few nitpicks in the driver, v6 should be fine:

>
> Signed-off-by: Robert Munteanu <rombert@apache.org>
> ---
>  drivers/hid/Kconfig        |  7 ++++
>  drivers/hid/Makefile       |  1 +
>  drivers/hid/hid-ids.h      |  1 +
>  drivers/hid/hid-quirks.c   |  3 ++
>  drivers/hid/hid-redragon.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 101 insertions(+)
>  create mode 100644 drivers/hid/hid-redragon.c
>
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 19c499f5623d..1125e4813716 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -560,6 +560,13 @@ config HID_MAYFLASH
>         Say Y here if you have HJZ Mayflash PS3 game controller adapters
>         and want to enable force feedback support.
>
> +config HID_REDRAGON
> +       tristate "Redragon keyboards"
> +       depends on HID
> +       default !EXPERT
> +       ---help---
> +    Support for Redragon keyboards that need fix-ups to work properly.
> +
>  config HID_MICROSOFT
>         tristate "Microsoft non-fully HID-compliant devices"
>         depends on HID
> diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> index eb13b9e92d85..a36f3f40ba63 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -84,6 +84,7 @@ hid-picolcd-$(CONFIG_DEBUG_FS)                += hid-picolcd_debugfs.o
>
>  obj-$(CONFIG_HID_PLANTRONICS)  += hid-plantronics.o
>  obj-$(CONFIG_HID_PRIMAX)       += hid-primax.o
> +obj-$(CONFIG_HID_REDRAGON)     += hid-redragon.o
>  obj-$(CONFIG_HID_RETRODE)      += hid-retrode.o
>  obj-$(CONFIG_HID_ROCCAT)       += hid-roccat.o hid-roccat-common.o \
>         hid-roccat-arvo.o hid-roccat-isku.o hid-roccat-kone.o \
> diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> index 9454ac134ce2..41a64d0e91f9 100644
> --- a/drivers/hid/hid-ids.h
> +++ b/drivers/hid/hid-ids.h
> @@ -599,6 +599,7 @@
>  #define USB_VENDOR_ID_JESS             0x0c45
>  #define USB_DEVICE_ID_JESS_YUREX       0x1010
>  #define USB_DEVICE_ID_ASUS_MD_5112     0x5112
> +#define USB_DEVICE_ID_REDRAGON_ASURA   0x760b
>
>  #define USB_VENDOR_ID_JESS2            0x0f30
>  #define USB_DEVICE_ID_JESS2_COLOR_RUMBLE_PAD 0x0111
> diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
> index e92b77fa574a..5f1253f1739a 100644
> --- a/drivers/hid/hid-quirks.c
> +++ b/drivers/hid/hid-quirks.c
> @@ -557,6 +557,9 @@ static const struct hid_device_id hid_have_special_driver[] = {
>  #if IS_ENABLED(CONFIG_HID_PRODIKEYS)
>         { HID_USB_DEVICE(USB_VENDOR_ID_CREATIVELABS, USB_DEVICE_ID_PRODIKEYS_PCMIDI) },
>  #endif
> +#if IS_ENABLED(CONFIG_HID_REDRAGON)
> +       { HID_USB_DEVICE(USB_VENDOR_ID_JESS,  USB_DEVICE_ID_REDRAGON_ASURA) },
> +#endif

Please drop this hunk. v4.16 should work without changing
hid_have_special_driver. This way, you will be sure that an initramfs
that doesn't include hid-redragon.ko will allo people to type their
LUKS password.

>  #if IS_ENABLED(CONFIG_HID_RETRODE)
>         { HID_USB_DEVICE(USB_VENDOR_ID_FUTURE_TECHNOLOGY, USB_DEVICE_ID_RETRODE2) },
>  #endif
> diff --git a/drivers/hid/hid-redragon.c b/drivers/hid/hid-redragon.c
> new file mode 100644
> index 000000000000..ff98a5dbb8e2
> --- /dev/null
> +++ b/drivers/hid/hid-redragon.c
> @@ -0,0 +1,89 @@
> +/*
> + *  HID driver for Redragon keyboards
> + *
> + *  Copyright (c) 2017 Robert Munteanu
> + *  SPDX-License-Identifier: GPL-2.0
> + */
> +
> +/*
> + * 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>

you probably don't need input.h

> +#include <linux/hid.h>
> +#include <linux/module.h>
> +#include <linux/log2.h>

log2.h? I am not sure you need it either

> +#include <linux/input-event-codes.h>

probably drop this one too.

> +
> +#include "hid-ids.h"
> +
> +
> +/*
> + * The Redragon Asura keyboard sends an incorrect HID descriptor.
> + * At byte 100 it contains
> + *
> + *   0x81, 0x00
> + *
> + * which is Input (Data, Arr, Abs), but it should be
> + *
> + *   0x81, 0x02
> + *
> + * which is Input (Data, Var, Abs), which is consistent with the way
> + * key codes are generated.
> + */
> +
> +static __u8 *redragon_report_fixup(struct hid_device *hdev, __u8 *rdesc,
> +       unsigned int *rsize)
> +{
> +       if (*rsize >= 102 && rdesc[100] == 0x81 && rdesc[101] == 0x00) {
> +               dev_info(&hdev->dev, "Fixing Redragon ASURA report descriptor.\n");
> +               rdesc[101] = 0x02;
> +       }
> +
> +       return rdesc;
> +}
> +
> +static int redragon_probe(struct hid_device *dev,
> +       const struct hid_device_id *id)
> +{
> +       int ret;
> +
> +       ret = hid_parse(dev);
> +       if (ret) {
> +               hid_err(dev, "parse failed\n");
> +               return ret;
> +       }
> +
> +       /* do not register unused input device */
> +       if (dev->maxapplication == 1)
> +               return 0;
> +
> +       ret = hid_hw_start(dev, HID_CONNECT_DEFAULT);
> +       if (ret) {
> +               hid_err(dev, "hw start failed\n");
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +static const struct hid_device_id redragon_devices[] = {
> +       {HID_USB_DEVICE(USB_VENDOR_ID_JESS, USB_DEVICE_ID_REDRAGON_ASURA)},
> +       {}
> +};
> +
> +MODULE_DEVICE_TABLE(hid, redragon_devices);
> +
> +static struct hid_driver redragon_driver = {
> +       .name = "redragon",
> +       .id_table = redragon_devices,
> +       .report_fixup = redragon_report_fixup,
> +       .probe = redragon_probe
> +};
> +
> +module_hid_driver(redragon_driver);
> +
> +MODULE_LICENSE("GPL");

The SPDX header says GPL-v2. And IIRC if there is the SPDX header you
can drop the MODULE_LICENSE (not entirely sure though).

Cheers,
Benjamin

> --
> 2.16.3
>