Re: [PATCH V5 11/18] clk: tegra210: Add support for Tegra210 clocks
From: Sowjanya Komatineni <skomatineni@nvidia.com>
Date: 2019-07-18 17:42:01
Also in:
linux-clk, linux-gpio, linux-tegra, lkml
On 7/18/19 10:22 AM, Sowjanya Komatineni wrote:
On 7/18/19 9:34 AM, Dmitry Osipenko wrote:quoted
18.07.2019 4:15, Sowjanya Komatineni пишет: [snip]quoted
quoted
quoted
Please try to fix all missing dependencies and orderings.Peter, dfllCPU_OUT is the first one to go thru restore when clk_restore_context traverses thru the list. dfllCPU_OUT has dependency on DFLL_ref and DFLL_SOC but this dependency is unknown to clock-tree. We can add DFLL_REF and DFLL_SOC as parents to dfllCPU_OUT during register so dfllCPU_OUT save/restore happens after their parents are restored. But DFLL needs both of these to be restored before DFLLCPU_Out and as DFLL_SOC restore always happens after the REF, thinking to add DFLL_SOC as parent to dfllCPU_OUT so save/restore follows after their dependencies. Please comment.Did quick try and I see by adding dfll-soc as parent to dfllCPU_OUT, its in proper order after all its dependencies. Can now add dfll save/restore to do dfll reinit during restore..If dfllCPU_OUT can work properly with dfll-soc being disabled, then this kind of dependency isn't very correct and just papers over the real problem, which is that there should be a way for CCF to specify multiple dependencies for the clock or the reverse ordering should be used for the restoring.dfll will not work without dfll-soc enabled. CLDVFS control logic is split into 2 clock domains. dvfs_ref_clk and dvfs_soc_clk. Majority of the control logic is clocked from dvfs_soc_clk for interfacing control registers.
Note on reverse ordering for restore. Currently restore order goes thru clock list and for each root goes thru parent -> child restore. this order is correct and also all clocks are parented properly so they follow proper order. dfllCPU is the only one where current driver doesn't take care of dependency in dfll_soc which gets enabled only after dfll_ref. Based on dfllCPU control logic module design, dfll_ref and dfll_soc should be enabled prior to dfll init/enable. So parenting dfll_soc to dfllCPU keeps proper order.