diff options
| author | Pali Rohár <pali@kernel.org> | 2021-04-08 13:42:18 +0200 |
|---|---|---|
| committer | Viresh Kumar <viresh.kumar@linaro.org> | 2021-04-09 15:17:33 +0530 |
| commit | 4decb9187589f61fe9fc2bc4d9b01160b0a610c5 (patch) | |
| tree | f42a52d6245ccdae8dc7333c333258950601ef60 /drivers/clk | |
| parent | d118ac2062b5b8331c8768ac81e016617e0996ee (diff) | |
| download | linux-4decb9187589f61fe9fc2bc4d9b01160b0a610c5.tar.bz2 | |
clk: mvebu: armada-37xx-periph: Fix switching CPU freq from 250 Mhz to 1 GHz
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>
Diffstat (limited to 'drivers/clk')
| -rw-r--r-- | drivers/clk/mvebu/armada-37xx-periph.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c index 6507bd2c5f31..b15e177bea7e 100644 --- a/drivers/clk/mvebu/armada-37xx-periph.c +++ b/drivers/clk/mvebu/armada-37xx-periph.c @@ -487,8 +487,10 @@ 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 @@ -498,15 +500,15 @@ 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); |