From: Pali Rohár pali@kernel.org
[ Upstream commit 4decb9187589f61fe9fc2bc4d9b01160b0a610c5 ]
It was observed that the workaround introduced by commit 61c40f35f5cd ("clk: mvebu: armada-37xx-periph: Fix switching CPU rate from 300Mhz to 1.2GHz") when base CPU frequency is 1.2 GHz is also required when base CPU frequency is 1 GHz. Otherwise switching CPU frequency directly from L2 (250 MHz) to L0 (1 GHz) causes a crash.
When base CPU frequency is just 800 MHz no crashed were observed during switch from L2 to L0.
Signed-off-by: Pali Rohár pali@kernel.org Acked-by: Stephen Boyd sboyd@kernel.org Acked-by: Gregory CLEMENT gregory.clement@bootlin.com Tested-by: Tomasz Maciej Nowak tmn505@gmail.com Tested-by: Anders Trier Olesen anders.trier.olesen@gmail.com Tested-by: Philip Soares philips@netisense.com Fixes: 2089dc33ea0e ("clk: mvebu: armada-37xx-periph: add DVFS support for cpu clocks") Signed-off-by: Viresh Kumar viresh.kumar@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clk/mvebu/armada-37xx-periph.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c index d5226ab8e26f..5193dc817197 100644 --- a/drivers/clk/mvebu/armada-37xx-periph.c +++ b/drivers/clk/mvebu/armada-37xx-periph.c @@ -485,8 +485,10 @@ static long clk_pm_cpu_round_rate(struct clk_hw *hw, unsigned long rate, }
/* - * Switching the CPU from the L2 or L3 frequencies (300 and 200 Mhz - * respectively) to L0 frequency (1.2 Ghz) requires a significant + * Workaround when base CPU frequnecy is 1000 or 1200 MHz + * + * Switching the CPU from the L2 or L3 frequencies (250/300 or 200 MHz + * respectively) to L0 frequency (1/1.2 GHz) requires a significant * amount of time to let VDD stabilize to the appropriate * voltage. This amount of time is large enough that it cannot be * covered by the hardware countdown register. Due to this, the CPU @@ -496,15 +498,15 @@ static long clk_pm_cpu_round_rate(struct clk_hw *hw, unsigned long rate, * To work around this problem, we prevent switching directly from the * L2/L3 frequencies to the L0 frequency, and instead switch to the L1 * frequency in-between. The sequence therefore becomes: - * 1. First switch from L2/L3(200/300MHz) to L1(600MHZ) + * 1. First switch from L2/L3 (200/250/300 MHz) to L1 (500/600 MHz) * 2. Sleep 20ms for stabling VDD voltage - * 3. Then switch from L1(600MHZ) to L0(1200Mhz). + * 3. Then switch from L1 (500/600 MHz) to L0 (1000/1200 MHz). */ static void clk_pm_cpu_set_rate_wa(unsigned long rate, struct regmap *base) { unsigned int cur_level;
- if (rate != 1200 * 1000 * 1000) + if (rate < 1000 * 1000 * 1000) return;
regmap_read(base, ARMADA_37XX_NB_CPU_LOAD, &cur_level);