On Tue, 4 Oct 2011, Santosh Shilimkar wrote: > On Tuesday 04 October 2011 04:08 AM, Tony Lindgren wrote: > > * Nicolas Pitre <nico@xxxxxxxxxxx> [111003 14:36]: > >> On Mon, 3 Oct 2011, Tony Lindgren wrote: > >> > >>> 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. > > > > OK, I'll take a look at that. > > > I have tried __arm_ioremap_pfn() for some DDR mapping and it didn't > work as expected. The mapping was not getting created. Did you investigate why it wasn't created? Must have been a trivial issue surely? But you have to wait until memory management is fully initialized to call the real ioremap() though, which happens later during the boot. > Needless to say this can't be an IO memory. I later managed to get > around with it by using iotable_init() though downside is I have to > pick a static virtual address for the mapping. You are using either MT_MEMORY or MT_MEMORY_NONCACHED in your map_desc entry. So using e.g. __arm_ioremap(phys_addr, size, MT_MEMORY) should give you what you need, given that this is called late enough of course. > But I agree that SRAM mapping can be moved further down. We > just need to ensure that it's ready before we initialise SDRC > and PM code. SDRC reconfigure of DDR needs to be executed from > SRAM and of-course the PM WFI routine. Today we do SDRC init early > and that's the reason SRAM is mapped before that. So both of them > needs to be moved down in the boot to make it work. Note that it is best not to call iotable_init() outside of the mdesc->map_io call path. So either you reshuffle the initialization order so that the static mappings alre always in place before doing the ioremap() trick, or you use __arm_ioremap() later on. 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
