Messages in this thread | | | Subject | Re: [PATCH 5/5] firmware: add DECLARE_FW_CUSTOM_FALLBACK() annotation | From | Milo Kim <> | Date | Sun, 18 Dec 2016 12:50:43 +0900 |
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Hi Luis,
On 12/17/2016 01:14 AM, Luis R. Rodriguez wrote: > Milo if sysfs is used can't the old userspace be mapped to use the new > sysfs interface through a wrapper of some sort ? What exactly would be > needed to ensure old userspace will not break?
LP5521 and LP5523 have two ways to load hex code from the userspace - the sysfs and firmware I/F. So user program supports both interfaces. Even if the firmware I/F is not available, user can still run LED effect through the sysfs.
However, LP5562 and LP8501 support only single way which is the firmware I/F. So user-space program for LP5562/8501 should be modified if lp55xx removes the interface. My idea is
Phase 1) - create sysfs in LP5562 and LP8501 - use new sysfs inside the firmware I/F loading callback - mark the firmware callback as a deprecated interface
Phase 2) - remove the firmware I/F after all user program fixes the interface (but the problem is how can we get to know when this is done?)
> Why has no one cried > after the v4.0 custom fallback mechanism breaking ?
Well, I don't know the reason exactly but my guess is they maybe still using old kernel.
> How wide spread is this custom userspace ?
Device manufactures in Asia & North America requested lp55xx drivers, but I don't know how many vendors uses the firmware I/F. Some vendors embeds the binary code inside the driver instead of using user-program.
I understood it's a kind of troublesome work in terms of the maintenance. Sorry for that. I hope we have a consensus to resolve it. Thanks!
Best regards, Milo
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