Quoting Loic Poulain (2020-07-03 01:49:43) > From: Ilia Lin <ilialin@xxxxxxxxxxxxxx> > > Each of the CPU clusters (Power and Perf) on msm8996 are > clocked via 2 PLLs, a primary and alternate. There are also > 2 Mux'es, a primary and secondary all connected together > as shown below > > +-------+ > XO | | > +------------------>0 | > | | > PLL/2 | SMUX +----+ > +------->1 | | > | | | | > | +-------+ | +-------+ > | +---->0 | > | | | > +---------------+ | +----------->1 | CPU clk > |Primary PLL +----+ PLL_EARLY | | +------> > | +------+-----------+ +------>2 PMUX | > +---------------+ | | | | > | +------+ | +-->3 | > +--^+ ACD +-----+ | +-------+ > +---------------+ +------+ | > |Alt PLL | | > | +---------------------------+ > +---------------+ PLL_EARLY > > The primary PLL is what drives the CPU clk, except for times > when we are reprogramming the PLL itself (for rate changes) when > we temporarily switch to an alternate PLL. A subsequent patch adds > support to switch between primary and alternate PLL during rate > changes. > > The primary PLL operates on a single VCO range, between 600MHz > and 3GHz. However the CPUs do support OPPs with frequencies > between 300MHz and 600MHz. In order to support running the CPUs > at those frequencies we end up having to lock the PLL at twice > the rate and drive the CPU clk via the PLL/2 output and SMUX. > > Signed-off-by: Ilia Lin <ilialin@xxxxxxxxxxxxxx> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx> > --- Applied to clk-next
