Messages in this thread | | | From | "Loh, Tien Hock" <> | Subject | Re: [PATCH 1/1] drivers/misc: Add Intel System ID driver | Date | Thu, 2 Mar 2017 02:17:36 +0000 |
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On Rab, 2017-03-01 at 12:34 +0100, Arnd Bergmann wrote: > On Wed, Mar 1, 2017 at 11:42 AM, Loh, Tien Hock <tien.hock.loh@intel. > com> wrote: > > > > On Rab, 2017-03-01 at 10:01 +0100, Arnd Bergmann wrote: > > > > > > On Wed, Mar 1, 2017 at 8:23 AM, Loh, Tien Hock <tien.hock.loh@int > > > el.c > > > Another option would be to fold the timestamp into the revision > > > attribute, > > > but whether that is a reasonable place for it would in turn > > > depend on > > > what the timestamp signifies. > > > > > > Can you explain what the timestamp is used for? Does it identify > > > the > > > time that the hardware revision was made, the time that a > > > software > > > was built which was loaded into it, or something else? > > > What kind of user space application would need this information? > > I just checked, and it seems like we can't put this into soc > > subsystem. > > In FPGA, we now can do partial reconfiguration, which > > "reconfigures" > > the hardware to have an updated sysid and timestamp value, and the > > base > > address of the Intel System ID may also be changed. This would > > require > > the driver to be a module that will be removed, probed again. The > > soc > > subsystem doesn't seem to be a suitable place to add this driver. > Ah, I had not realized this is for fpga_manager. > > Why not put the attributes into /sys/class/fpga_manager/*/ then > along with the other attributes that exist there? That way, we have > an interface that works for all users of drivers/fpga/ >
Well, this is not only for fpga_manager, but often time used to ensure that the correct hardware is programmed into the FPGA by checking the sysid after fpga_manager reconfigures the hardware. Systems without fpga_manager can still use sysid and timestamp to ensure the hardware is as expected value.
What do you think of /sys/class/fpga_sysid/*/id and /sys/class/fpga_sysid/*/timestamp?
> > > > A note on the timestamp, in the old days this is used to check that > > the > > BSP is using the correct FPGA hardware. I believe in Linux we > > should do > > the same in the driver, and if it not, the driver should print a > > warning. The timestamp's print is not exactly needed. I'll add the > > feature into the driver in the next patch. > Ok. > > Arnd | |