Re: [PATCH v4 1/2] usb: core: Add quirk for 255-bytes initial config read

[Alan Stern]

On Tue, Jul 28, 2026 at 01:37:16PM +0530, Nikhil Solanke wrote:
> On Tue, 28 Jul 2026 at 07:29, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Also, it's odd that you add the quirk flag to the kernel without adding
> > a new quirk entry for the Xbox 360-compatible devices.  That doesn't
> > have to be done in this patch, though; it can be done in a follow-up.
> > (But note that without a followup this patch doesn't actually fix
> > anything, since a true fix would require user intervention.)
> >
> 
> Well the device I am using spoofs Microsoft's device IDs directly. I
> avoided adding it because the official xbox controllers work out of
> the box. It won't break their functionality, but it kinda falls into
> the category of "if it ain't broken, why fix it". Other clone devices
> use different VID:PID pair as well, like with what happened Ishaan's
> device (his reply to my previous patch revision). I believe they
> should be added here instead. Since there are many such devices,
> gathering all the IDs would take considerable time and community work.

Okay.  It's worth mentioning this in the patch description.

> Also, the kernel's own xpad module is slightly behind some changes or
> so I have heard. There are a few community maintained kernel
> modules/drivers with many changes that are required for these devices
> to actually function. There is some magic packet that needs to be sent
> after the usb device has initialized along with doing a bunch of other
> things like mapping out buttons, etc. These drivers are also required
> for a device to fully function in most cases (the builtin xpad also
> works in some cases). So just by adding a device to the quirk list
> wouldn't truly fix it.
> 
> There's still a lot of issues that need to be addressed in the kernel
> driver space to "truly" fix Xbox 360-compatible devices (majorly,
> hid-generic or other drivers claim the devices before these
> out-of-tree modules due to race conditions). My patch is just the
> first step.

Got it.

> Thanks! I would like to know your thoughts on the above points as to
> what should be preferably done moving forward. If it happens that I
> should send in another patch, I will address the nits and add the
> Acked-By as well.

That's up to you.  What you have done so far is already acceptable, IMO.

Alan Stern