Hi, This is to take the discussion forward which I started here http://marc.info/?l=linux-omap&m=130812942102354&w=2 on how to support the omap_pm_get_device_context_loss_count() api on OMAP4. I started to work on this and thought I almost had patches which would do the job on OMAP4,(keep a per-module/hwmod context count by looking at the per-module context registers that exist on OMAP4, similar to the per-pwrdm count maintained by looking at the per-pwrdm prepwrst registers on OMAP3) until I realized my approach had 2 issues -1- The book keeping (similar to whats done in pwrdm_pre_transition() and pwrdm_post_transition()) was turning out to be quite expensive to be done for *every* low power system/cpu transition. (Btw, some profiling shows me the existing book keeping is quite expensive already) -2- Doing this book keeping *only* during low power system/cpu transitions is'nt enough as there could be modules which can independently transition while the MPU and L3 are still active like DSS, ABE, GFX etc. This was avoided on OMAP3 with 'autodeps' as described in the discussion thread above which made book keeping in low power system/cpu transitions work for all. Issue -1- might be a little easy to solve if the book-keeping needs to be done only for domains/modules which transition along with the system/cpu. The book keeping can then only be done for specific C states (and suspend) instead of doing it for all C states. What I am unable to fix is Issue -2-. Me and Santosh discussed a lot on how to handle this and we thought with all the HW governed transitions, the only foolproof way of doing this was if the HW itself could log a count instead of just logging the state of previous transition. (Which is not the case on OMAP4 :-)) Does anyone else see any other way of handling this (Issue -2-) on OMAP4 in software? regards, Rajendra/Santosh -- 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
