Re: [PATCH v2] clk: meson-g12a: fix bit range for fixed sys and hifi pll

[Chuan Liu]

Hi Da:

    Thanks for your feedback. but this patch is wrong.


On 8/22/2025 8:22 AM, Da Xue wrote:
> [ EXTERNAL EMAIL ]
>
> The bit range 17:0 does not match the datasheet for A311D / S905D3.
> Change the bit range to 18:0 for FIX and HIFI PLLs to match datasheet.


The upper 2 bits (bit18, bit17) of the frac were deprecated long ago.
The actual effective bit field for frac is bit[16:0]. However, the
corresponding datasheet has not been updated. I will provide feedback
and update the datasheet accordingly.


> The frac field is missing for sys pll so add that as well.


PLLs with frac support are used in scenarios requiring a wide range
of output frequencies (e.g., audio/video applications).

Since sys_pll is dedicated to clocking the CPU and does not require
such frequency versatility, it does not support fractional frequency
multiplication.


> Patched:
>
> + sudo cat /sys/devices/system/cpu/cpufreq/policy0/cpuinfo_cur_freq \
> /sys/devices/system/cpu/cpufreq/policy2/cpuinfo_cur_freq
> 996999
> 500000
> + sudo cat /sys/kernel/debug/meson-clk-msr/measure_summary
> + grep -i '\(sys_\|hifi_\|fixed_\)pll'
>   hifi_pll                      0    +/-1562Hz
>   sys_pll_div16                 0    +/-1562Hz
>   sys_pll_cpub_div16            0    +/-1562Hz
> + sudo cat /sys/kernel/debug/clk/clk_summary
> + grep -i '\(sys_\|hifi_\|fixed_\)pll'
>      hifi_pll_dco                     0       0        0        0
>         hifi_pll                      0       0        0        0
>      sys_pll_dco                      1       1        0        3999999985
>         sys_pll                       0       0        0        499999999
>            sys_pll_div16_en           0       0        0        499999999
>               sys_pll_div16           0       0        0        31249999
>      fixed_pll_dco                    1       1        1        3987999985
>         fixed_pll                     3       3        1        1993999993
>
> Unpatch:
>
> + sudo cat /sys/devices/system/cpu/cpufreq/policy0/cpuinfo_cur_freq \
> /sys/devices/system/cpu/cpufreq/policy2/cpuinfo_cur_freq
> 1000000
> 500000
> + sudo cat /sys/kernel/debug/meson-clk-msr/measure_summary
> + grep -i '\(sys_\|hifi_\|fixed_\)pll'
>   hifi_pll                      0    +/-1562Hz
>   sys_pll_div16                 0    +/-1562Hz
>   sys_pll_cpub_div16            0    +/-1562Hz
> + sudo cat /sys/kernel/debug/clk/clk_summary
> + grep -i '\(sys_\|hifi_\|fixed_\)pll'
>      hifi_pll_dco                     0       0        0        0
>         hifi_pll                      0       0        0        0
>      sys_pll_dco                      1       1        0        4800000000
>         sys_pll                       0       0        0        1200000000
>            sys_pll_div16_en           0       0        0        1200000000
>               sys_pll_div16           0       0        0        75000000
>      fixed_pll_dco                    1       1        1        3999999939
>         fixed_pll                     3       3        1        1999999970
>
> Fixes: 085a4ea93d54 ("clk: meson: g12a: add peripheral clock controller")
> Signed-off-by: Da Xue <da@libre.computer>
> ---
>   drivers/clk/meson/g12a.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c
> index 66f0e817e416..f78cca619ca5 100644
> --- a/drivers/clk/meson/g12a.c
> +++ b/drivers/clk/meson/g12a.c
> @@ -157,7 +157,7 @@ static struct clk_regmap g12a_fixed_pll_dco = {
>                  .frac = {
>                          .reg_off = HHI_FIX_PLL_CNTL1,
>                          .shift   = 0,
> -                       .width   = 17,
> +                       .width   = 19,
>                  },
>                  .l = {
>                          .reg_off = HHI_FIX_PLL_CNTL0,
> @@ -223,6 +223,11 @@ static struct clk_regmap g12a_sys_pll_dco = {
>                          .shift   = 10,
>                          .width   = 5,
>                  },
> +               .frac = {
> +                       .reg_off = HHI_SYS_PLL_CNTL1,
> +                       .shift   = 0,
> +                       .width   = 19,
> +               },
>                  .l = {
>                          .reg_off = HHI_SYS_PLL_CNTL0,
>                          .shift   = 31,
> @@ -1901,7 +1906,7 @@ static struct clk_regmap g12a_hifi_pll_dco = {
>                  .frac = {
>                          .reg_off = HHI_HIFI_PLL_CNTL1,
>                          .shift   = 0,
> -                       .width   = 17,
> +                       .width   = 19,
>                  },
>                  .l = {
>                          .reg_off = HHI_HIFI_PLL_CNTL0,
> --
> 2.47.2
>
>
> _______________________________________________
> linux-amlogic mailing list
> linux-amlogic@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-amlogic