From: Benjamin Tissoires <bentiss@kernel.org>
To: Zhouwang Huang <honjow311@gmail.com>
Cc: Jiri Kosina <jikos@kernel.org>,
denis.benato@linux.dev, linux-kernel@vger.kernel.org,
linux-input@vger.kernel.org
Subject: Re: [PATCH] HID: core: add short report quirk and use it for GPD Win (2f24:0137)
Date: Wed, 8 Apr 2026 17:41:28 +0200 [thread overview]
Message-ID: <adZ2PTzQ05iObcGt@beelink> (raw)
In-Reply-To: <20260407173212.86942-1-honjow311@gmail.com>
Hi,
Definitely not a big fan of that new quirk. The issue is that current
hid-core fix is too restrictive because it doesn't have enough
information, like the actual allocated buffer size.
On Apr 08 2026, Zhouwang Huang wrote:
> Commit 9e2a17d2e808 ("HID: gpd: fix report descriptor on GPD Win
> handheld (2f24:0137)") used report_fixup to shrink Report Count from
> 63 to 11 so that short reports from firmware <= 1.09 would not be
> rejected by hid_report_raw_event().
>
> However, firmware 1.10 fixed the report length and now sends the full
> 63 bytes. Because report_fixup already shrank the descriptor,
> usbhid allocates a 12-byte URB buffer — far too small for the 64-byte
> transfer — causing continuous -EOVERFLOW on every interrupt-in URB.
> The HID report descriptor and bcdDevice are identical across firmware
> versions, so report_fixup cannot conditionally apply.
OK, so if a firmware already fixed the bug, I'll drop 9e2a17d2e808 from
for-next and not include it in the final 7.0 PR I'll need to send. We
can tell people to upgrade to the latest firmware while I work on a
proper fix.
BTW, technically we could also not change the report descriptor if we
detect the correct firmware version. That would be easier to implement
than a global quirk. But hopefully we won't have to do anything and get
the proper hid-core fix soon.
Cheers,
Benjamin
>
> Replace the report_fixup driver with a new per-device quirk
> HID_QUIRK_ALLOW_SHORT_REPORTS. When set, hid_report_raw_event()
> zero-pads short reports instead of rejecting them — the same behaviour
> the core had before commit 0a3fe972a7cb ("HID: core: Mitigate
> potential OOB by removing bogus memset()"). The descriptor is left
> unmodified so the URB buffer matches the declared report size and works
> with any firmware version.
>
> Remove hid-gpd.c, its Kconfig entry and Makefile line; the device is
> now handled by hid-generic with the quirk applied from hid-quirks.c.
>
> Fixes: 9e2a17d2e808 ("HID: gpd: fix report descriptor on GPD Win handheld (2f24:0137)")
> Signed-off-by: Zhouwang Huang <honjow311@gmail.com>
> ---
> drivers/hid/Kconfig | 10 --------
> drivers/hid/Makefile | 1 -
> drivers/hid/hid-core.c | 11 +++++----
> drivers/hid/hid-gpd.c | 52 ----------------------------------------
> drivers/hid/hid-quirks.c | 2 ++
> include/linux/hid.h | 2 ++
> 6 files changed, 11 insertions(+), 67 deletions(-)
> delete mode 100644 drivers/hid/hid-gpd.c
>
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 2159d0fb7020..c1d9f7c6a5f2 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -419,16 +419,6 @@ config HID_GLORIOUS
> Support for Glorious PC Gaming Race mice such as
> the Glorious Model O, O- and D.
>
> -config HID_GPD
> - tristate "GPD Win handheld OEM HID support"
> - depends on USB_HID
> - help
> - Report descriptor fix for the OEM USB HID interface (GameSir
> - 2f24:0137) found on GPD Win handhelds. The firmware declares 63-byte
> - reports but only sends 11 bytes, which the HID core rejects.
> -
> - Say Y or M here if you use a GPD Win handheld with this interface.
> -
> config HID_HOLTEK
> tristate "Holtek HID devices"
> depends on USB_HID
> diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> index f69cd6015465..e01838239ae6 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -53,7 +53,6 @@ obj-$(CONFIG_HID_ELO) += hid-elo.o
> obj-$(CONFIG_HID_EVISION) += hid-evision.o
> obj-$(CONFIG_HID_EZKEY) += hid-ezkey.o
> obj-$(CONFIG_HID_FT260) += hid-ft260.o
> -obj-$(CONFIG_HID_GPD) += hid-gpd.o
> obj-$(CONFIG_HID_GEMBIRD) += hid-gembird.o
> obj-$(CONFIG_HID_GFRM) += hid-gfrm.o
> obj-$(CONFIG_HID_GLORIOUS) += hid-glorious.o
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index f5587b786f87..52e86f927a38 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2057,10 +2057,13 @@ int hid_report_raw_event(struct hid_device *hid, enum hid_report_type type, u8 *
> rsize = max_buffer_size;
>
> if (csize < rsize) {
> - hid_warn_ratelimited(hid, "Event data for report %d was too short (%d vs %d)\n",
> - report->id, rsize, csize);
> - ret = -EINVAL;
> - goto out;
> + if (!(hid->quirks & HID_QUIRK_ALLOW_SHORT_REPORTS)) {
> + hid_warn_ratelimited(hid, "Event data for report %d was too short (%d vs %d)\n",
> + report->id, rsize, csize);
> + ret = -EINVAL;
> + goto out;
> + }
> + memset(cdata + csize, 0, rsize - csize);
> }
>
> if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_report_event)
> diff --git a/drivers/hid/hid-gpd.c b/drivers/hid/hid-gpd.c
> deleted file mode 100644
> index 5b4d203e2499..000000000000
> --- a/drivers/hid/hid-gpd.c
> +++ /dev/null
> @@ -1,52 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-or-later
> -/*
> - * HID report descriptor fixup for GPD Win handhelds.
> - *
> - * The OEM HID interface (VID 2f24 / GameSir, PID 0137) declares Report ID 1
> - * with Report Count 63 (8-bit fields) for both Input and Feature, but the
> - * firmware only sends 11 bytes of payload after the report ID.
> - */
> -
> -#include <linux/hid.h>
> -#include <linux/module.h>
> -
> -#include "hid-ids.h"
> -
> -#define RDESC_LEN 38
> -#define RPT_COUNT_INPUT_OFF 21
> -#define RPT_COUNT_FEATURE_OFF 34
> -
> -static const __u8 *gpd_report_fixup(struct hid_device *hdev, __u8 *rdesc,
> - unsigned int *rsize)
> -{
> - if (*rsize != RDESC_LEN)
> - return rdesc;
> -
> - if (rdesc[RPT_COUNT_INPUT_OFF - 1] == 0x95 &&
> - rdesc[RPT_COUNT_INPUT_OFF] == 0x3f &&
> - rdesc[RPT_COUNT_FEATURE_OFF - 1] == 0x95 &&
> - rdesc[RPT_COUNT_FEATURE_OFF] == 0x3f) {
> - hid_info(hdev, "fixing report counts (63 -> 11 bytes)\n");
> - rdesc[RPT_COUNT_INPUT_OFF] = 11;
> - rdesc[RPT_COUNT_FEATURE_OFF] = 11;
> - }
> -
> - return rdesc;
> -}
> -
> -static const struct hid_device_id gpd_devices[] = {
> - { HID_USB_DEVICE(USB_VENDOR_ID_GAMESIR, USB_DEVICE_ID_GAMESIR_0137) },
> - { }
> -};
> -MODULE_DEVICE_TABLE(hid, gpd_devices);
> -
> -static struct hid_driver gpd_driver = {
> - .name = "gpd",
> - .id_table = gpd_devices,
> - .report_fixup = gpd_report_fixup,
> -};
> -
> -module_hid_driver(gpd_driver);
> -
> -MODULE_DESCRIPTION("HID report descriptor fix for GPD Win handheld (GameSir 2f24:0137)");
> -MODULE_LICENSE("GPL");
> diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
> index f6be3ffee023..b9ae1442eba9 100644
> --- a/drivers/hid/hid-quirks.c
> +++ b/drivers/hid/hid-quirks.c
> @@ -97,6 +97,8 @@ static const struct hid_device_id hid_quirks[] = {
> HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE },
> { HID_USB_DEVICE(USB_VENDOR_ID_GAMEVICE, USB_DEVICE_ID_GAMEVICE_KISHI),
> HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE },
> + { HID_USB_DEVICE(USB_VENDOR_ID_GAMESIR, USB_DEVICE_ID_GAMESIR_0137),
> + HID_QUIRK_ALLOW_SHORT_REPORTS },
> { HID_USB_DEVICE(USB_VENDOR_ID_HAPP, USB_DEVICE_ID_UGCI_DRIVING), HID_QUIRK_BADPAD | HID_QUIRK_MULTI_INPUT },
> { HID_USB_DEVICE(USB_VENDOR_ID_HAPP, USB_DEVICE_ID_UGCI_FIGHTING), HID_QUIRK_BADPAD | HID_QUIRK_MULTI_INPUT },
> { HID_USB_DEVICE(USB_VENDOR_ID_HAPP, USB_DEVICE_ID_UGCI_FLYING), HID_QUIRK_BADPAD | HID_QUIRK_MULTI_INPUT },
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index 31324609af4d..212dd13bfcfa 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -381,6 +381,7 @@ struct hid_item {
> * | @HID_QUIRK_X_INVERT:
> * | @HID_QUIRK_Y_INVERT:
> * | @HID_QUIRK_IGNORE_MOUSE:
> + * | @HID_QUIRK_ALLOW_SHORT_REPORTS: accept shorter-than-expected reports, zero-pad
> * | @HID_QUIRK_SKIP_OUTPUT_REPORTS:
> * | @HID_QUIRK_SKIP_OUTPUT_REPORT_ID:
> * | @HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP:
> @@ -408,6 +409,7 @@ struct hid_item {
> #define HID_QUIRK_X_INVERT BIT(12)
> #define HID_QUIRK_Y_INVERT BIT(13)
> #define HID_QUIRK_IGNORE_MOUSE BIT(14)
> +#define HID_QUIRK_ALLOW_SHORT_REPORTS BIT(15)
> #define HID_QUIRK_SKIP_OUTPUT_REPORTS BIT(16)
> #define HID_QUIRK_SKIP_OUTPUT_REPORT_ID BIT(17)
> #define HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP BIT(18)
> --
> 2.53.0
>
>
next prev parent reply other threads:[~2026-04-08 15:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-07 17:32 [PATCH] HID: core: add short report quirk and use it for GPD Win (2f24:0137) Zhouwang Huang
2026-04-08 15:41 ` Benjamin Tissoires [this message]
2026-04-08 16:07 ` Zhouwang Huang
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