On Mon, 3 Oct 2011, Tony Lindgren wrote: > * Nicolas Pitre <nico@xxxxxxxxxxx> [111003 11:26]: > > > > The problem is that those ioremap() calls are performed _*before*_ the > > memory is fully set up yet, and also even before the corresponding > > static mappings are even in place! So not only is the ioremap code > > unoperational at this point, but a generic way to trap ioremap() calls > > in order to toss a static mapping back won't even work here because > > iotable_init() was not even called yet. > > > > The current code get away with it because OMAP is providing its own > > __arch_ioremap() which does the interception and provide a virtual > > address from hardcoded but yet to exist mappings. But the goal of > > global kernel maintenance is to _remove_ such SOC-specific special cases > > and move such a perfectly valid optimization into core code where it can > > be applied uniformly to all. So the OMAP __arch_ioremap() is going > > away, meaning that static mappings have to be in place before ioremap() > > calls can return something minimally usable. > > Sure this would be nice to fix, see below. Great! > > OK, so let's modify omap4_panda_map_io() just to test this one board and > > reverse the omap44xx_map_common_io() and omap2_set_globals_443x() call > > order. Now the mappings will be there before ioremap() is called. But > > that, too, doesn't work and the kernel now complains with: > > > > |OMAP revision unknown, please fix! > > |Uninitialized omap_chip, please fix! > > |Could not detect SRAM size > > > > But it looks like omap2_set_globals_tap() still has to be called first! > > Isn't this wonderfully convoluted? > > We've already unravelled some of that with the init_early changes. > > Earlier having the IO space moving around between 2420/2430/3430 > meant that we had to map some IO to detect the SoC. Now we have > SoC specific initcalls where we assume the SoC category is initialized > from board-*.c file (and from DT at some point). But the map_io method always has been tied to machine specific descriptors. That always implied a fixed SoC category, no? Unless you have a machine which can accommodate multiple different SOCs but that's very uncommon. > Having the SRAM base address move around with different sizes also > requires the SoC detection.. Otherwise we can end up mapping wrong > size and end up trying to access secure SRAM that will hang the system. > > The way to fix it is to move SRAM init happen much later so we don't > have to map it early. I guess now we could use ioremap for SRAM, > although we may not want device attributes for the executable code? > Got any suggestions here on how we should map SRAM later on? You can use a variant of ioremap() such as __arm_ioremap() which let you specify the memory attribute. > > So could someone in the OMAP camp fix this nonsense ASAP please? > > Of course, yesterday would be best. > > Heh. Were working on it. So far it's been moving things to get initialized > later, separate sys_timer code from dmtimer driver features, initialize > only the hwmods needed for sys_timer early, SoC specific initcalls to > clear the SoC detection out of the early init path and so on. Wonderful! > > Furthermore... there is also a static mapping for physical address > > 0x4e000000 using virtual address 0xff100000 which is already reserved > > for other purposes i.e. the consistent DMA area. It is not immediately > > obvious where this comes from without being intimate with the OMAP code. > > Can this be fixed as well i.e. moved elsewhere please? > > This sounds like a bug somewhere. Which omap are you seeing this on? OMAP4430 on a Panda board. Here are the static mappings I'm seeing: phys = 0x44000000 virt = 0xf8000000 size = 0x100000 phys = 0x4a000000 virt = 0xfc000000 size = 0x400000 phys = 0x50000000 virt = 0xf9000000 size = 0x100000 phys = 0x4c000000 virt = 0xfd100000 size = 0x100000 phys = 0x4d000000 virt = 0xfe100000 size = 0x100000 phys = 0x4e000000 virt = 0xff100000 size = 0x100000 <--- phys = 0x48000000 virt = 0xfa000000 size = 0x400000 phys = 0x54000000 virt = 0xfe800000 size = 0x800000 It is also possible that I might have screwed something up on my side. What is located at 0x4e000000? Nicolas -- 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
