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. >>>>> 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? 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
