Matthias, On Wed, Mar 20, 2019 at 03:02:23PM -0700, Matthias Kaehlcke wrote: > 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. > Oops, I wanted to say when odt_enable changes since last call. > 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. > So, for a reason that I ignore, if we try to save unecessary calls to ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD (odt_enable has not changed since last call), we get stalled in the call to ROCKCHIP_SIP_CONFIG_SET_RAGE that follows. The function arm_smccc_smc never returns and the device hard hang. Thanks to your remark, I have also fixed an issue with the odt_dis_freq value. Its value is initialized to 0 in the probe function. Thus the odt_enable is always true (target_rate > 0). I moved its initialization after the timings are parsed from the device-tree; its value is now none zero (333000000 in my case). > > Also, the call takes around 300us. > > Thanks for the info! > > Matthias > > _______________________________________________ > Linux-rockchip mailing list > Linux-rockchip@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-rockchip Gaël
