Re: [PATCH 2/2] ARM: OMAP2: Fix GPMC memory initialisation

[Tony Lindgren <tony@atomide.com>]

* Jon Hunter <jon-hunter@ti.com> [130204 07:09]:
> 
> On 02/02/2013 12:11 PM, Tony Lindgren wrote:
> > * Jon Hunter <jon-hunter@ti.com> [130201 17:25]:
> >>
> >> On 02/01/2013 03:51 PM, Tony Lindgren wrote:
> >>>
> >>> How about let's fix this properly to start with so we don't add
> >>> more blockers moving this code to drivers/bus?
> >>>
> >>> Looks like gpmc_mem_init() gets called from gpmc_probe() so
> >>> we can pass that information in pdev.
> >>
> >> I wondered if you would suggest that ;-)
> > 
> > :)
> >  
> >> I definitely can and it is probably best. Things like this become
> >> painful when we move to device-tree. We really need a generic way for
> >> passing stuff like this to drivers for omap. Our options are auxdata or
> >> bus notifiers. I am wondering whether we can plug pdata in the
> >> omap_device bus notifier for device-tree. Let me know if you have any
> >> thoughts.
> > 
> > Hmm but in this case can't you just do it based on the compatible
> > flag? For legacy systems we also need to pass it in pdata.
> 
> This is a boot-time configuration. So really you need to read the
> control status register at boot and then determine the mapping. We could
> store the address of the control status read in the pdata, but I think
> that is a bit of a hack.

Ah right. Well once we have Haojian's generic pinconf patches merged for
pinctrl-single, we can set up the CONTROL_STATUS register as a
pinctrl-single,bits register and query the SYSBOOT_3 pin value directly
from the driver.

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.
 
> > 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.

Regards,

Tony