From 843be1e7fb30f6309aa9389344b16dca57e6d4e2 Mon Sep 17 00:00:00 2001 From: Rajendra Nayak Date: Mon, 23 Jan 2017 09:56:21 +0530 Subject: clk: qcom: gdsc: Fix handling of hw control enable/disable Once a gdsc is brought in and out of HW control, there is a power down and up cycle which can take upto 1us. Polling on the gdsc status immediately after the hw control enable/disable can mislead software/firmware to belive the gdsc is already either on or off, while its yet to complete the power cycle. To avoid this add a 1us delay post a enable/disable of HW control mode. Also after the HW control mode is disabled, poll on the status to check gdsc status reflects its 'on' before force disabling it in software. Reported-by: Stanimir Varbanov Reviewed-by: Stanimir Varbanov Tested-by: Stanimir Varbanov Signed-off-by: Rajendra Nayak Fixes: 904bb4f5c7de ("clk: qcom: gdsc: Add support for gdscs with HW control") Signed-off-by: Stephen Boyd --- drivers/clk/qcom/gdsc.c | 58 ++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 45 insertions(+), 13 deletions(-) (limited to 'drivers/clk/qcom') diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c index 288186cce0ae..a4f3580587b7 100644 --- a/drivers/clk/qcom/gdsc.c +++ b/drivers/clk/qcom/gdsc.c @@ -63,11 +63,26 @@ static int gdsc_hwctrl(struct gdsc *sc, bool en) return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val); } +static int gdsc_poll_status(struct gdsc *sc, unsigned int reg, bool en) +{ + ktime_t start; + + start = ktime_get(); + do { + if (gdsc_is_enabled(sc, reg) == en) + return 0; + } while (ktime_us_delta(ktime_get(), start) < TIMEOUT_US); + + if (gdsc_is_enabled(sc, reg) == en) + return 0; + + return -ETIMEDOUT; +} + static int gdsc_toggle_logic(struct gdsc *sc, bool en) { int ret; u32 val = en ? 0 : SW_COLLAPSE_MASK; - ktime_t start; unsigned int status_reg = sc->gdscr; ret = regmap_update_bits(sc->regmap, sc->gdscr, SW_COLLAPSE_MASK, val); @@ -100,16 +115,7 @@ static int gdsc_toggle_logic(struct gdsc *sc, bool en) udelay(1); } - start = ktime_get(); - do { - if (gdsc_is_enabled(sc, status_reg) == en) - return 0; - } while (ktime_us_delta(ktime_get(), start) < TIMEOUT_US); - - if (gdsc_is_enabled(sc, status_reg) == en) - return 0; - - return -ETIMEDOUT; + return gdsc_poll_status(sc, status_reg, en); } static inline int gdsc_deassert_reset(struct gdsc *sc) @@ -188,8 +194,20 @@ static int gdsc_enable(struct generic_pm_domain *domain) udelay(1); /* Turn on HW trigger mode if supported */ - if (sc->flags & HW_CTRL) - return gdsc_hwctrl(sc, true); + if (sc->flags & HW_CTRL) { + ret = gdsc_hwctrl(sc, true); + if (ret) + return ret; + /* + * Wait for the GDSC to go through a power down and + * up cycle. In case a firmware ends up polling status + * bits for the gdsc, it might read an 'on' status before + * the GDSC can finish the power cycle. + * We wait 1us before returning to ensure the firmware + * can't immediately poll the status bits. + */ + udelay(1); + } return 0; } @@ -204,9 +222,23 @@ static int gdsc_disable(struct generic_pm_domain *domain) /* Turn off HW trigger mode if supported */ if (sc->flags & HW_CTRL) { + unsigned int reg; + ret = gdsc_hwctrl(sc, false); if (ret < 0) return ret; + /* + * Wait for the GDSC to go through a power down and + * up cycle. In case we end up polling status + * bits for the gdsc before the power cycle is completed + * it might read an 'on' status wrongly. + */ + udelay(1); + + reg = sc->gds_hw_ctrl ? sc->gds_hw_ctrl : sc->gdscr; + ret = gdsc_poll_status(sc, reg, true); + if (ret) + return ret; } if (sc->pwrsts & PWRSTS_OFF) -- cgit v1.2.3