Messages in this thread | | | Subject | SYSFS: need a noncaching read | From | Heiko Schocher <> | Date | Tue, 11 Sep 2007 11:43:17 +0200 |
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Hello,
I have developed a device driver and use the sysFS to export some registers to userspace. I opened the sysFS File for one register and did some reads from this File, but I alwas becoming the same value from the register, whats not OK, because they are changing. So I found out that the sysFS caches the reads ... :-(
Is there a way to retrigger the reads (in that way, that the sysFS rereads the values from the driver), without closing and opening the sysFS Files? Or must I better use the ioctl () Driver-interface for exporting these registers?
I am asking this, because I must read every 10 ms 2 registers, so doing a open/read/close for reading one registers is a little bit too much overhead.
I made a sysFS seek function, which retriggers the read, and that works fine, but I have again 2 syscalls, whats also is not optimal.
Or can we make a open () with a (new?)Flag, that informs the sysFS to always reread the values from the underlying driver?
Or a new flag in the "struct attribute_group" in include/linux/sysfs.h, which let the sysfs rereading the values?
suggestions are welcome
thanks Heiko -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
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