Re: [2.6.23-rc9 regression] commit 4f01a757 broke HAL input support

[Anssi Hannula]

Ben Gamari wrote:
> On Thu, 2007-10-04 at 22:40 -0400, Dmitry Torokhov wrote:
> > 4f01a757e75f2a3cab2bab89c4176498963946b9.
>
> The change that Dmitry proposed would still require
> CONFIG_SYSFS_DEPRECATED, right?

What proposed change?
The changeset you quote is already applied.

Andrey Borzenkov wrote:
> > Actually this specific problem was introduced by 
> > 4f01a757e75f2a3cab2bab89c4176498963946b9. This commit seems to have 
> > completely disassociated eventX from corresponding inputY
> >
> > To summarize.
> >
> > 1. Any kernel with SYSFS_DEPRECATED unset
> >
> > events are sent for /devices/...
> > /devices/.../eventX is direct child of /devices/.../inputY
> > HAL checks for parent of eventX, finds inputY and is happy
> >
> > 2. SYSFS_DEPRECATED=y, pre-2.6.23 kernel
> >
> > events are sent for /class/...
> > /class/.../eventX is direct child of /class/.../inputY
> > HAL checks for parent of eventX, finds inputY and works
> >
> > 3. SYSFS_DEPRECATED=y, 2.6.23 before commit 
> > 4f01a757e75f2a3cab2bab89c4176498963946b9. 
> >
> > events are sent for /class/...
> > /class/.../eventX is *not* child of /class/.../inputY
> > /class/.../eventX/device points to .../inputY
> > HAL checks for .../device link, finds inputY and works
> >
> > 4. SYSFS_DEPRECATED=y, 2.6.23 after commit 
> > 4f01a757e75f2a3cab2bab89c4176498963946b9. 
> >
> > /class/.../eventX is *not* child of /class/.../inputY
> > /class/.../eventX/device points to some physical device
> > HAL finds inputY neither as ../inputY nor as device link and breaks
> >
> > But what is worse, now the only way to find which inputY corresponds to which 
> > eventX is to scan the whole /class/input, check for device link and compare. 

> > I am afraid that we have to bite the bullet and just accept that 2.6.23 breaks 
> > user space this way or that. Frankly fixing path_id seems to be the least 
> > evil.

I'd hate to see such breakage. IMO the sysfs structure of input devices 
should be made compatible with both HAL and udev, with both 
CONFIG_SYSFS_DEPRECATED and without it, as in 2.6.22 and before.

> > Is it possible to fall back to /class/input/inputX/eventY if SYSFS_DEPRECATED 
> > is set?

Hopefully.

--
Anssi Hannula
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