From: Dmitry Osipenko <digetx@gmail.com>
Date: Thu, 9 Jul 2020 20:20:57 +0300
Subject: clk: tegra: pll: Improve PLLM enable-state detection

Git-commit: fa64023763cf1a3da8bf3341df6c2a47e54fcead
Patch-mainline: v5.9-rc1
References: jsc#SLE-15847

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@gmail.com>
Link: https://lore.kernel.org/r/20200709172057.13951-1-digetx@gmail.com
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 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 0b212cf2e794..f180c055d33f 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_clk_is_gated_by_pmc(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);
+}
+
 static int clk_pll_is_enabled(struct clk_hw *hw)
 {
 	struct tegra_clk_pll *pll = to_clk_pll(hw);
 	u32 val;
 
-	if (pll->params->flags & TEGRA_PLLM) {
-		val = readl_relaxed(pll->pmc + PMC_PLLP_WB0_OVERRIDE);
-		if (val & PMC_PLLP_WB0_OVERRIDE_PLLM_OVERRIDE)
-			return val & PMC_PLLP_WB0_OVERRIDE_PLLM_ENABLE ? 1 : 0;
-	}
+	/*
+	 * Power Management Controller (PMC) can override the PLLM clock
+	 * settings, including the enable-state. The PLLM is enabled when
+	 * PLLM's CaR state is ON and when PLLM isn't gated by PMC.
+	 */
+	if ((pll->params->flags & TEGRA_PLLM) && pllm_clk_is_gated_by_pmc(pll))
+		return 0;
 
 	val = pll_readl_base(pll);
 
-- 
2.26.2