On Tue, Mar 6, 2012 at 7:32 PM, Nishanth Menon <nm@xxxxxx> wrote: > From: Yuan Jiangli <jlyuan@xxxxxxxxxxxx> > > commit 2f34ce81b8c05c900e45bd88595cc154f7bb5957 > (OMAP3: PM: Adding voltage driver support.) > introduced runtime computation of waittime to handle all potential > sys clocks available. > > In the voltage processor, the SPMSUpdateWait is calculated based on > the slew rate and the voltage step (SMPSUpdateWait = slew rate * > Voltage Step). After the voltage processor receives the SMPS_Ack > signal, the Voltage Controller will wait for SMPSUpdateWait clock > cycles for the voltage to settle to the new value. For all > practical purposes, the waittime parameter is the OMAP hardware > translation of what the slew rate on the PMIC is. > > As an example, with TPS62361 on OMAP4460, > step_size = 10000 > slew_rate = 32000 > sys_clk_rate = 38400 > > Our current computation results in the following: > = ((step_size / slew_rate) * sys_clk_rate) / 1000 > = ((10000 / 32000) * 38400 / 1000 > = 0 > > Fix the same using DIV_ROUND_UP as an extra wait clock cycle > is better than lesser clock cycle. For the above example, this > translates to: > = (10000 * 38400) / (1000 * 32000) > = 12 > > Change-Id: I0ee22e60555e1cfd6cc3dea7ee44d0584ce182b6 You don't need above gerrit change id in commit message. Regardas 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
