Messages in this thread | | | Date | Mon, 27 Nov 2006 13:04:21 -0700 | From | "Jordan Crouse" <> | Subject | Re: char: Add MFGPT driver for the CS5535/CS5536 |
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On 22/11/06 22:17 +0000, Alan wrote: > > The attached driver provides a low-level interface to the block, and > > allows for other kernel drivers to use the timers. > > Three comments > > 2. There is an RTC timer interface - could you use that interface > for some of this so its compatible and consistent ?
Do you mean, use the RTC interface itself (i.e. - turn the mfgpt driver into an RTC driver), or just emulate parts of the RTC interface in the MFGPT driver. I would be fine with the second option - the first doesn't really fit, since the only functionality the RTC and the MFGPT share is the periodic interrupt feature (which is sub-optimal on RTC anyway).
If the "timer interrupt" feature feels tacked on, thats because it is. The best use for the MFGPT block is to drive a duty cycle on the output pin suitable for LEDs and such. Most Geode customers would use it for that purpose. Running a close second on the usefulness scale is the watchdog timer - its always nice to have that sort of functionality available at the hardware level (and its a double bonus that the watchdog can be set up to continue running while in suspend).
The interrupt/NMI functionality was added to the hardware for the BIOS to use, and we added it to the kernel driver for a sense of completeness. I personally can't fathom anybody using the timers, and I would gladly remove them if nobody else can come up with a realistic usage model.
> 3. Ditto for a watchdog use - although that would be a separate > driver using the kernel hooks anyway.
That was the plan - I do have a watchdog driver that I had when I first wrote the MFGPT driver for a now defunct project. I should dust it off and add it in.
Thanks, Jordan
-- Jordan Crouse Senior Linux Engineer Advanced Micro Devices, Inc. <www.amd.com/embeddedprocessors>
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