From 25bb2cec88401a512c01adc8b815f8a579da2558 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Mon, 3 Aug 2015 14:23:29 +0200 Subject: [PATCH] drm/tegra: sor: Factor out tegra_sor_set_parent_clock() Switching the SOR parent clock can glitch if done while the clock is enabled. Extract a common function that can be used to disable the module clock, switch the parent and reenable the module clock. Signed-off-by: Thierry Reding --- drivers/gpu/drm/tegra/sor.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c index 757c6e8603af..ed03a1f5b692 100644 --- a/drivers/gpu/drm/tegra/sor.c +++ b/drivers/gpu/drm/tegra/sor.c @@ -225,6 +225,23 @@ static inline void tegra_sor_writel(struct tegra_sor *sor, u32 value, writel(value, sor->regs + (offset << 2)); } +static int tegra_sor_set_parent_clock(struct tegra_sor *sor, struct clk *parent) +{ + int err; + + clk_disable_unprepare(sor->clk); + + err = clk_set_parent(sor->clk, parent); + if (err < 0) + return err; + + err = clk_prepare_enable(sor->clk); + if (err < 0) + return err; + + return 0; +} + static int tegra_sor_dp_train_fast(struct tegra_sor *sor, struct drm_dp_link *link) { @@ -733,7 +750,8 @@ static int tegra_sor_power_down(struct tegra_sor *sor) if ((value & SOR_PWR_TRIGGER) != 0) return -ETIMEDOUT; - err = clk_set_parent(sor->clk, sor->clk_safe); + /* switch to safe parent clock */ + err = tegra_sor_set_parent_clock(sor, sor->clk_safe); if (err < 0) dev_err(sor->dev, "failed to set safe parent clock: %d\n", err); @@ -1219,7 +1237,8 @@ static void tegra_sor_edp_enable(struct drm_encoder *encoder) return; } - err = clk_set_parent(sor->clk, sor->clk_safe); + /* switch to safe parent clock */ + err = tegra_sor_set_parent_clock(sor, sor->clk_safe); if (err < 0) dev_err(sor->dev, "failed to set safe parent clock: %d\n", err); @@ -1326,10 +1345,10 @@ static void tegra_sor_edp_enable(struct drm_encoder *encoder) value &= ~SOR_PLL2_PORT_POWERDOWN; tegra_sor_writel(sor, value, SOR_PLL2); - /* switch to DP clock */ - err = clk_set_parent(sor->clk, sor->clk_dp); + /* switch to DP parent clock */ + err = tegra_sor_set_parent_clock(sor, sor->clk_dp); if (err < 0) - dev_err(sor->dev, "failed to set DP parent clock: %d\n", err); + dev_err(sor->dev, "failed to set parent clock: %d\n", err); /* power DP lanes */ value = tegra_sor_readl(sor, SOR_DP_PADCTL0); @@ -1781,7 +1800,8 @@ static void tegra_sor_hdmi_enable(struct drm_encoder *encoder) reset_control_deassert(sor->rst); - err = clk_set_parent(sor->clk, sor->clk_safe); + /* switch to safe parent clock */ + err = tegra_sor_set_parent_clock(sor, sor->clk_safe); if (err < 0) dev_err(sor->dev, "failed to set safe parent clock: %d\n", err); @@ -1892,7 +1912,8 @@ static void tegra_sor_hdmi_enable(struct drm_encoder *encoder) tegra_sor_writel(sor, 0x00000000, SOR_XBAR_POL); - err = clk_set_parent(sor->clk, sor->clk_parent); + /* switch to parent clock */ + err = tegra_sor_set_parent_clock(sor, sor->clk_parent); if (err < 0) dev_err(sor->dev, "failed to set parent clock: %d\n", err); -- 2.20.1