On 11/13/2013 06:41 PM, Tomasz Figa wrote: > 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. I believe SMP is enabled before any initcalls. > 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. Unfortunately, non-secure mode platforms like highbank and omap have to make platform specific smc calls. Rob -- 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
 |