linux-kernel - Re: [PATCH] HID: i2c-hid: override HID descriptors for some Haptick 5288 touchpads

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Message-ID: <ngcltngjjl5dc4nt5i3ui5pjvemt26kp4iqpbcpbllvwwbonfd@yspyfi423i3w>
Date: Tue, 13 Jan 2026 16:00:35 +0100
From: Benjamin Tissoires <bentiss@...nel.org>
To: kenkinming2002@...il.com
Cc: jikos@...nel.org, linux-input@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] HID: i2c-hid: override HID descriptors for some Haptick
 5288 touchpads

On Jan 13 2026, kenkinming2002@...il.com wrote:
> On Thu, Jan 08, 2026 at 02:14:29AM +0800, kenkinming2002@...il.com wrote:
> > > The simplest "solution" following what you are doing is making a HID-BPF
> > > fixup which checks whether the device properly sent the report
> > > descriptor and if not puts the one here. The HID-BPF has the advantage
> > > of being compatible with hid-multitouch so you won't get into troubles
> > > with a separate module.
> > This might be a solution but would that not only fix it just for me? I
> > would have to look into how to do HID-BPF fixup.
> An update, I have looked into HID-BPF but it seems to me that we can
> only fix up the HID report descriptor and not the HID descriptor (this
> descriptor is specific to i2c-hid device) but from my testing both
> descriptor can be corrupted. Specifically, I see messages such as:
> 
>   i2c_hid_acpi i2c-SPPT2600:00: unexpected HID descriptor bcdVersion (0x0209)
>   i2c_hid_acpi i2c-SPPT2600:00: Failed to fetch the HID Descriptor
> 
> appearing in my log.
> 
> For now, I am just going to just apply the patch locally for myself till
> a better solution come up.

On second thoughts, maybe we can have the HID descriptor dmi quirk in
the kernel only. This way, the device should be presented to HID-BPF and
the HID stack, and if there is something wrong in the descriptor, this
shouldn't fail dramatically.

The HID descriptor is something specific to i2c-hid, so it's fine
"fixing" it there. The report descriptor can be fixed later on I think.

Cheers,
Benjamin

> 
> I have finally clean up the pile of garbage I have while investigating
> the problem and put up a proper git repository with relevant script and
> logs at https://github.com/kenkinming2002/samsung-i2c-hid-bug-repro.git.
> 
> Huge thanks to Benjamin and anyway who might have stumbled across this
> patch for your time.
> 
> Yours sincerly,
> Ken Kwok