Messages in this thread | | | From | John Stultz <> | Date | Tue, 8 May 2018 16:17:35 -0700 | Subject | Userland breakage from "Modify the device name as devfreq(X) for sysfs" |
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Hey folks, I wanted to bring up an issue we've recently tripped over, which was caused by 4585fbcb5331f ("PM / devfreq: Modify the device name as devfreq(X) for sysfs"). https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=4585fbcb5331fc910b7e553ad3efd0dd7b320d14
That patch replaced paths like: /sys/class/devfreq/ddr_devfreq/min_freq and /sys/class/devfreq/e82c0000.mali/min_freq
With /sys/class/devfreq/devfreq(0)/min_freq and /sys/class/devfreq/devfreq(1)/min_freq
This broke userspace we have that needs to work on 4.4, 4.9 and 4.14 (and on).
I wanted to try to ask to understand more about the rational for this patch, as it doesn't make much sense to me, particularly as now it is less obvious as to which path is for which device - and more worrisome it could change depending on initialization order.
Unfortunately, this wasn't noticed very quickly, as the patch has been upstream now for some time. But I wanted to better understand why this change was made, and see if we might consider reverting it, or alternatively consider provide multiple sysfs links (both dev_name and devfreq(N)) so that we can preserve compatibility?
Thoughts? -john
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