diff options
| author | Roman Stratiienko <r.stratiienko@gmail.com> | 2022-07-05 10:52:26 +0300 |
|---|---|---|
| committer | Jernej Skrabec <jernej.skrabec@gmail.com> | 2022-07-08 18:13:50 +0200 |
| commit | 4167ac8a657e4f0860419adf24d4b91a26580488 (patch) | |
| tree | 2d2be2a4b98da10728e1cb13947de7ff5449ed9f /drivers/clk | |
| parent | b17403a56064c63b10dc56884b99114355f03e57 (diff) | |
clk: sunxi-ng: sun50i: h6: Modify GPU clock configuration to support DFS
Using simple bash script it was discovered that not all CCU registers
can be safely used for DFS, e.g.:
while true
do
devmem 0x3001030 4 0xb0003e02
devmem 0x3001030 4 0xb0001e02
done
Script above changes the GPU_PLL multiplier register value. While the
script is running, the user should interact with the user interface.
Using this method the following results were obtained:
| Register | Name | Bits | Values | Result |
| -- | -- | -- | -- | -- |
| 0x3001030 | GPU_PLL.MULT | 15..8 | 20-62 | OK |
| 0x3001030 | GPU_PLL.INDIV | 1 | 0-1 | OK |
| 0x3001030 | GPU_PLL.OUTDIV | 0 | 0-1 | FAIL |
| 0x3001670 | GPU_CLK.DIV | 3..0 | ANY | FAIL |
DVFS started to work seamlessly once dividers which caused the
glitches were set to fixed values.
Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220705075226.359475-1-r.stratiienko@gmail.com
Diffstat (limited to 'drivers/clk')
| -rw-r--r-- | drivers/clk/sunxi-ng/ccu-sun50i-h6.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/clk/sunxi-ng/ccu-sun50i-h6.c b/drivers/clk/sunxi-ng/ccu-sun50i-h6.c index 1a5e418923f6..30056da3e0af 100644 --- a/drivers/clk/sunxi-ng/ccu-sun50i-h6.c +++ b/drivers/clk/sunxi-ng/ccu-sun50i-h6.c @@ -95,13 +95,13 @@ static struct ccu_nkmp pll_periph1_clk = { }, }; +/* For GPU PLL, using an output divider for DFS causes system to fail */ #define SUN50I_H6_PLL_GPU_REG 0x030 static struct ccu_nkmp pll_gpu_clk = { .enable = BIT(31), .lock = BIT(28), .n = _SUNXI_CCU_MULT_MIN(8, 8, 12), .m = _SUNXI_CCU_DIV(1, 1), /* input divider */ - .p = _SUNXI_CCU_DIV(0, 1), /* output divider */ .common = { .reg = 0x030, .hw.init = CLK_HW_INIT("pll-gpu", "osc24M", @@ -294,9 +294,9 @@ static SUNXI_CCU_M_WITH_MUX_GATE(deinterlace_clk, "deinterlace", static SUNXI_CCU_GATE(bus_deinterlace_clk, "bus-deinterlace", "psi-ahb1-ahb2", 0x62c, BIT(0), 0); +/* Keep GPU_CLK divider const to avoid DFS instability. */ static const char * const gpu_parents[] = { "pll-gpu" }; -static SUNXI_CCU_M_WITH_MUX_GATE(gpu_clk, "gpu", gpu_parents, 0x670, - 0, 3, /* M */ +static SUNXI_CCU_MUX_WITH_GATE(gpu_clk, "gpu", gpu_parents, 0x670, 24, 1, /* mux */ BIT(31), /* gate */ CLK_SET_RATE_PARENT); @@ -1191,6 +1191,16 @@ static int sun50i_h6_ccu_probe(struct platform_device *pdev) if (IS_ERR(reg)) return PTR_ERR(reg); + /* Force PLL_GPU output divider bits to 0 */ + val = readl(reg + SUN50I_H6_PLL_GPU_REG); + val &= ~BIT(0); + writel(val, reg + SUN50I_H6_PLL_GPU_REG); + + /* Force GPU_CLK divider bits to 0 */ + val = readl(reg + gpu_clk.common.reg); + val &= ~GENMASK(3, 0); + writel(val, reg + gpu_clk.common.reg); + /* Enable the lock bits on all PLLs */ for (i = 0; i < ARRAY_SIZE(pll_regs); i++) { val = readl(reg + pll_regs[i]); |