On 02/04/2013 01:47 PM, Tony Lindgren wrote: > * Jon Hunter <jon-hunter@xxxxxx> [130204 11:37]: >> >> On 02/04/2013 01:15 PM, Tony Lindgren wrote: >>> * Jon Hunter <jon-hunter@xxxxxx> [130204 10:49]: >>>> On 02/04/2013 11:45 AM, Tony Lindgren wrote: >>>>> >>>>> AFAIK SYSBOOT_n values reflect the boot time values of the actual SYSBOOT >>>>> pins, so using generic pinconf there makes sense. But this of course should >>>>> be checked. >>>> >>>> Not sure I am a fan of that idea. It is possible the pins could be >>>> re-used as GPIOs after reset. Given that the state at reset is latched >>>> in a register, it is best just to read the register directly. >>> >>> Yes the physical SYSBOOT pins can be reused as GPIO, but that's are already >>> handled by the padconf and GPIO registers. This is a different register >>> showing the boot time pin values for some pins. So it makes sense to use >>> generic pinconf to make the pin values available to the client drivers >>> as needed. >>> >>> The advantage doing it this way is that we don't need to export any omap >>> custom functions to the drivers from the SCM driver. This way we need zero >>> platform glue code, and can deal with it directly in the drivers in a >>> generic way. And all we need to do is just need to map the SoC specific >>> SYSBOOT pin register in the .dts files. >> >> I see what you are saying exporting the state in control_status register >> via the pinconf. That could work. >> >>> It may also make sense to export DEVICETYPE this way. At least early omaps >>> had the GP vs HS mode configured by pulls on some pins during the boot time. >>> So those bits too may reflect actual physical pins during the boot time >>> configured by the efuse settings? >> >> I *believe* that was only omap1. > > Yeah but maybe the efuses just configure some pulls for selected pins for > later omaps? > >>>>>>> Regarding omap_device, we should find a way to keep the dependencies >>>>>>> between drivers and the bus code down to minimum. So ideally things >>>>>>> like this would be only done using just the compatible flag. But the >>>>>>> pdata we cannot remove quite yet. >>>>>> >>>>>> Agree. However, there are several drivers today (gpio, dmtimer, mmc, >>>>>> serial, dss, etc), that make use of a function pointer to >>>>>> omap_pm_get_dev_context_loss_count() to determine when the peripheral's >>>>>> state has been lost. When booting with DT this function pointer is not >>>>>> populated and so with DT we currently have no way to determine this. I >>>>>> see this as a blocker to migrating completely to DT. Ideally we would >>>>>> find a way for RPM to handle this and remove the function pointer. >>>>>> However, right now we still need a generic way to pass this type of >>>>>> platform data to drivers. >>>>> >>>>> Yeah pinconf generic won't help us with the legacy boot. >>>> >>>> Right. I view all this sort of thing as system-level device information >>>> that some drivers may need. It does not seem that we have a good way to >>>> handle that at the moment. Any ideas? >>> >>> I suggest just passing it in in pdata for now for the legacy boot. Then >>> I suggest we make what we can generic with pinconf in the long run. >> >> I don't see why we would want to export a function pointer to >> omap_pm_get_dev_context_loss_count() with pinconf. Have we got our wires >> crossed here? > > Yes sorry, too many muxes here. I got this topic mixed up with the sysboot > pin topic :) > > We really need to find a Linux generic API to query this. Sounds like it > should be part of runtime PM? Ideally, yes. I had discussed with Kevin about adding a new state for "logic state lost" and then if this could be passed to the RPM resume callback then we could use this. May be I need to bring this up with Tero. Cheers Jon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
