Hi Will, On Friday 25 of October 2013 14:48:52 Will Deacon wrote: > On Sat, Oct 19, 2013 at 03:04:22PM +0100, Tomasz Figa wrote: > > On Saturday 19 of October 2013 18:09:15 Sachin Kamat wrote: > > > Hi Tomasz, > > > > > > On 17 October 2013 18:35, Tomasz Figa <t.figa@xxxxxxxxxxx> wrote: > > > > Hi Sachin, > > > > > > > > On Thursday 17 of October 2013 17:33:12 Sachin Kamat wrote: > > > >> L2x0 cache controller is present only in Cortex-A9 based Exynos4 SoCs. > > > >> Thus move this function to Exynos4 early init call to avoid non-Exynos4 > > > >> SoCs from calling this function in multi-platform support. > > > > > > > > I believe that at the time .init_early() is called there is no ioremap() > > > > infrastructure working yet and so L2 cache initialization which needs > > > > it will cause a kernel panic. This patch worked only because currently > > > > there is no L2X0 controller defined in device tree sources of Exynos 4. > > > > > > It is not clear to me as to why device tree entry is required for this > > > to work in current form > > > as we call the L2X0 init function explicitly. > > > > L2x0 controller is just another IP block on the SoC. In addition its > > registers are memory mapped and the driver needs some way to get their > > location. The function being called explicitly simply scans device tree > > for applicable node and performs rest of the setup only if it finds one. > > > > Ideally there should be no need to call this function explicitly, as it > > should be called by some code based on presence of applicable device tree > > node. > > It's a nice idea, but you need to be careful if you start deferring this > stuff. Aside from the potential performance loss during early boot, I'm not > even sure that the l2x0_init function is safe to run with IRQs enabled. > > Will I just realised that I have not replied to your message, sorry for that. So, my intention was not deferring this, but rather making this more generic. In case of Exynos, we call l2x0_of_init() from an early_initcall which is long time already after enabling interrupts, but still before SMP is initialized. My idea was to create a generic early_initcall in arch/arm/mm/cache-l2x0.c that would scan DT for applicable node, parse aux_val and aux_mask from such node (if found) and then initialize L2X0 without any need for having platform-specific code. However my concern here is whether on some platforms such platform code wouldn't be needed anyway. Unfortunately I don't really know enough about L2X0 to be able to answer this myself, at least at the moment. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
 |