09.07.2020 12:49, Jon Hunter пишет: > > On 08/07/2020 08:54, Dmitry Osipenko wrote: >> Power Management Controller (PMC) can override the PLLM clock settings, >> including the enable-state. Although PMC could only act as a second level >> gate, meaning that PLLM needs to be enabled by the Clock and Reset >> Controller (CaR) anyways if we want it to be enabled. Hence, when PLLM is >> overridden by PMC, it needs to be enabled by CaR and ungated by PMC in >> order to be functional. Please note that this patch doesn't fix any known >> problem, and thus, it's merely a minor improvement. >> >> Link: https://lore.kernel.org/linux-arm-kernel/20191210120909.GA2703785@ulmo/T/ >> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx> >> --- >> >> Changelog: >> >> v3: - Dropped unintended code change that was accidentally added to v2. >> >> v2: - Added clarifying comment to the code. >> >> - Prettified the code. >> >> drivers/clk/tegra/clk-pll.c | 20 +++++++++++++++----- >> 1 file changed, 15 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/clk/tegra/clk-pll.c b/drivers/clk/tegra/clk-pll.c >> index b2d39a66f0fa..37cfcd6836c9 100644 >> --- a/drivers/clk/tegra/clk-pll.c >> +++ b/drivers/clk/tegra/clk-pll.c >> @@ -327,16 +327,26 @@ int tegra_pll_wait_for_lock(struct tegra_clk_pll *pll) >> return clk_pll_wait_for_lock(pll); >> } >> >> +static bool pllm_pmc_clk_enabled(struct tegra_clk_pll *pll) >> +{ >> + u32 val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE); >> + >> + return !(val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE) || >> + (val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE); >> +} >> + > > > I am not sure that the name of the above function really reflects what > it is doing. If it was enabled, isn't it the AND of these bits? > > Futhermore, what we really want to know is if the override is enabled, > but the PMC PLLM enable is not set. In other words, the PMC is gating > the clock. So maybe we should have a function that is called something > like pllm_clk_is_gated_by_pmc(). Yeah, the name indeed could be improved + the logic could be inverted in order to make it all more clear. Thank you for the suggestion! I'll prepare the v4.
