Hi Gaël, On Wed, Mar 20, 2019 at 05:50:13PM -0400, Gaël PORTAY wrote: > Hi Matthias, > > On Tue, Mar 19, 2019 at 05:33:52PM -0700, Matthias Kaehlcke wrote: > > ... > > > @@ -95,6 +103,19 @@ static int rk3399_dmcfreq_target(struct device *dev, > > > unsigned long *freq, > > > > > > mutex_lock(&dmcfreq->lock); > > > > > > + if (target_rate >= dmcfreq->odt_dis_freq) > > > + odt_enable = true; > > > + > > > + /* > > > + * This makes a SMC call to the TF-A to set the DDR PD (power-down) > > > + * timings and to enable or disable the ODT (on-die termination) > > > + * resistors. > > > + */ > > > + arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, dmcfreq->odt_pd_arg0, > > > + dmcfreq->odt_pd_arg1, > > > + ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD, > > > + odt_enable, 0, 0, 0, &res); > > > > Is it necessary/desirable to make this call for every frequency > > change? IIUC it should be only needed when odt_enable changes and the > > driver could track the state. If the DDR frequency doesn't change too > > often and the overhead of the call is small it shouldn't be really > > important though. > > > > I will test your solution first to make sure there is no regression to > run that call for frequency change only.
If there is no frequency change the function returns at the beginning. My suggestion was to only do the call when 'odt_enable' changes, i.e. when a change (up or down) passes the 'odt_dis_freq' threshold. > Also, the call takes around 300us. Thanks for the info! Matthias
