Messages in this thread | | | Date | Fri, 28 Nov 2014 15:10:10 -0800 | From | Guenter Roeck <> | Subject | Re: [PATCH 2/2] ARM: imx: src: support vf610 system reset controller |
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On 11/28/2014 03:00 PM, Stefan Agner wrote: > On 2014-11-28 23:22, Arnd Bergmann wrote: >> On Friday 28 November 2014 23:09:09 Stefan Agner wrote: >>> On 2014-11-28 22:24, Arnd Bergmann wrote: >>>> On Friday 28 November 2014 22:02:01 Stefan Agner wrote: >>>> >>>>>> If the SRC is also capable of resetting individual blocks instead of just >>>>>> the entire machine, it would be a reset driver in drivers/reset instead. >>>>> >>>>> Beside the system reset, there is only a mask functionality for the >>>>> watchdogs (there are two watchdogs, one for Cortex-A5 and one for the >>>>> M4). This makes the SRC module in the Vybrid a bit different then what >>>>> is available on other i.MX SoC's... >>>> >>>> If you already have the watchdog registers in there and want to have >>>> a watchdog driver too, the easiest way would be to register the reboot >>>> handler from the watchdog driver. >>> >>> Hm, not sure we speak about the same here. The SRC module has two >>> (multi-)bit fields to mask the watchdog reset event for each watchdog. >>> Beside that, there are two full watchdog register maps, which are in >>> different areas. There is already a driver for this watchdogs. I'm not >>> sure what the idea behind this is exactly, I guess it would easily allow >>> to (temporary) mask the other CPU's watchdog. However, I don't think we >>> need that functionality, so I don't care about that right now. >> >> Ok, I see, thanks for the clarification! >> >>> There is also a restart handler in the watchdog driver, but I prefer to >>> use the reset capabilities of the SRC since it has immediate effect. >>> >>> Lets get to the big picture again: I could register the whole SRC >>> register map as a syscon device and then access the registers from my >>> suspend/resume implementation later on. And similar in the restart >>> driver, I would use syscon_regmap_lookup_by_compatible to check if it >>> contains the vf610-src compatible string and register the restart >>> driver/handler if available. >> >> Correct, and also in the watchdog driver, I guess. >> >> Instead of syscon_regmap_lookup_by_compatible, please use >> syscon_regmap_lookup_by_phandle and put the link to the syscon >> device into the device accessing it. >> >> Also, see if you can use or extend drivers/power/reset/syscon-reboot.c >> for your use case. > > Nice, this allows to do the reset with almost no code. The only thing > which might be a problem is the priority: I used 192 since 128 is > already used by the watchdog driver. Maybe we can change that > syscon-reboot is a bit above watchdogs by default, or maybe even a dt > property? I will try to use that driver for v2. Thx! >
A dt property might make more sense if the syscon driver is to be used for multiple systems. Otherwise, no matter what you pick, it will be wrong for some system.
Guenter
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