From a7ce40508803d7ac1e642a93e80709ee2514c1c2 Mon Sep 17 00:00:00 2001 From: Caesar Wang Date: Tue, 1 Dec 2015 17:13:24 +0800 Subject: [PATCH] clk: rockchip: Force rk3368 PWM clock (and its parents) on Most rk3368 boards (especially those with Pmic that followed the lead from rk3368-evb-act8846) have a PWM regulator on them for vdd_logic. This is the main voltage for all kinds of misc stuff including the memory controller. On these boards it is critically important to make sure that the PWM never ever glitches and never loses its clock. Any glitch could crash the system. Right now there are no users of the PWM regulator and also Linux thinks that the PWM regulator is disabled. Things happen to work because firmware configured the PWM and Linux doesn't touch it. ..and the PWM's clock is marked as "ignore unused". ...but things _stop_ working if we turn off serial console. Why? Because: 1. Serial console shares a parent clock with the PWM (pclk_cpu) 2. If we have no serial console then nobody is holding pclk_cpu on at reboot time. It gets disabled. We need to fix a lot of the above problems, but until we get everything right the cleanest "hack" seems like it is to just keep the "rk_pwm" clock on always. Signed-off-by: Caesar Wang Signed-off-by: Heiko Stuebner --- drivers/clk/rockchip/clk-rk3368.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/clk/rockchip/clk-rk3368.c b/drivers/clk/rockchip/clk-rk3368.c index 7e6b783e6eee..1834b6ad6725 100644 --- a/drivers/clk/rockchip/clk-rk3368.c +++ b/drivers/clk/rockchip/clk-rk3368.c @@ -819,6 +819,11 @@ static struct rockchip_clk_branch rk3368_clk_branches[] __initdata = { }; static const char *const rk3368_critical_clocks[] __initconst = { + /* + * pwm1 supplies vdd_logic on a lot of boards, is currently unhandled + * but needs to stay enabled there (including its parents) at all times. + */ + "pclk_pwm1", "pclk_pd_pmu", }; -- 2.20.1