* Kevin Hilman <khilman@xxxxxx> [120306 15:33]: > Nishanth Menon <nm@xxxxxx> writes: > > > 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 > > > > Acked-by: Jon Hunter <jon-hunter@xxxxxx> > > [nm@xxxxxx: slightly better implementation] > > Signed-off-by: Nishanth Menon <nm@xxxxxx> > > Signed-off-by: Yuan Jiangli <jlyuan@xxxxxxxxxxxx> > > Acked-by: Kevin Hilman <khilman@xxxxxx> > > Tony, I don't have any more PM fixes for this cycle, so feel free to add > this to fixes-non-critical-part2. > > This is an important fix, but since we're not doing active voltage > scaling in mainline today, I don't think it's 3.3 material. OK, adding. Thanks, Tony -- 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
