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SubjectRe: [PATCH v4 5/7] clk: axi-clkgen: Respect ZYNQMP PFD/VCO frequency limits
Hi Alexandru,

On Tue, Sep 29, 2020 at 05:44:15PM +0300, Alexandru Ardelean wrote:
> From: Mathias Tausen <mta@gomspace.com>
>
> Since axi-clkgen is now supported on ZYNQMP, make sure the max/min
> frequencies of the PFD and VCO are respected.
>
> Signed-off-by: Mathias Tausen <mta@gomspace.com>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>

This patch still does not cover the PCIe Zynq plugged into ZynqMP linux
machine case.

> ---
> drivers/clk/clk-axi-clkgen.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c
> index 4342b7735590..2319bb1c5c08 100644
> --- a/drivers/clk/clk-axi-clkgen.c
> +++ b/drivers/clk/clk-axi-clkgen.c
> @@ -108,12 +108,21 @@ static uint32_t axi_clkgen_lookup_lock(unsigned int m)
> return 0x1f1f00fa;
> }
>
> +#ifdef ARCH_ZYNQMP
> +static const struct axi_clkgen_limits axi_clkgen_default_limits = {
> + .fpfd_min = 10000,
> + .fpfd_max = 450000,
> + .fvco_min = 800000,
> + .fvco_max = 1600000,
> +};
> +#else
> static const struct axi_clkgen_limits axi_clkgen_default_limits = {
> .fpfd_min = 10000,
> .fpfd_max = 300000,
> .fvco_min = 600000,
> .fvco_max = 1200000,
> };
> +#endif

I still don't understand this. You have a way to determine which fabric
you are looking at with the FPGA info. Why not:

[..] axi_clkgen_zynqmp_default_limits = {
};

[..] axi_clkgen_default_limits = {
};

Set them based on what you read back, i.e. determine which fabric you
are looking at *per clock gen* and use that info, rather than making a
compile time decision to support only one of them.

Generally speaking #ifdef $ARCH should be a last resort solution.
>
> static void axi_clkgen_calc_params(const struct axi_clkgen_limits *limits,
> unsigned long fin, unsigned long fout,
> --
> 2.17.1
>

Cheers,
Moritz

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