Re: [PATCH v3 06/11] clk: tegra: remove EMC to MC clock mux in Tegra114

[Mikko Perttunen <mperttunen@nvidia.com>]

On Monday, September 15, 2025 5:01 PM Svyatoslav Ryhel wrote:
> Configure EMC without mux for correct EMC driver support.

Rather than just 'removing EMC to MC clock mux in Tegra114', I would say this patch removes current emc and emc_mux clocks and replaces them with the proper EMC clock implementation. I would edit the commit subject and commit message along those lines.

> 
> Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> ---
>  drivers/clk/tegra/clk-tegra114.c | 48 ++++++++++++++++++++++----------
>  1 file changed, 33 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/clk/tegra/clk-tegra114.c b/drivers/clk/tegra/clk-tegra114.c
> index 8bde72aa5e68..6b3a140772c2 100644
> --- a/drivers/clk/tegra/clk-tegra114.c
> +++ b/drivers/clk/tegra/clk-tegra114.c
> @@ -622,10 +622,6 @@ static const char *mux_plld_out0_plld2_out0[] = {
>  };
>  #define mux_plld_out0_plld2_out0_idx NULL
>  
> -static const char *mux_pllmcp_clkm[] = {
> -	"pll_m_out0", "pll_c_out0", "pll_p_out0", "clk_m", "pll_m_ud",
> -};
> -
>  static const struct clk_div_table pll_re_div_table[] = {
>  	{ .val = 0, .div = 1 },
>  	{ .val = 1, .div = 2 },
> @@ -672,7 +668,6 @@ static struct tegra_clk tegra114_clks[tegra_clk_max] __initdata = {
>  	[tegra_clk_csi] = { .dt_id = TEGRA114_CLK_CSI, .present = true },
>  	[tegra_clk_i2c2] = { .dt_id = TEGRA114_CLK_I2C2, .present = true },
>  	[tegra_clk_uartc] = { .dt_id = TEGRA114_CLK_UARTC, .present = true },
> -	[tegra_clk_emc] = { .dt_id = TEGRA114_CLK_EMC, .present = true },
>  	[tegra_clk_usb2] = { .dt_id = TEGRA114_CLK_USB2, .present = true },
>  	[tegra_clk_usb3] = { .dt_id = TEGRA114_CLK_USB3, .present = true },
>  	[tegra_clk_vde_8] = { .dt_id = TEGRA114_CLK_VDE, .present = true },
> @@ -1048,14 +1043,7 @@ static __init void tegra114_periph_clk_init(void __iomem *clk_base,
>  					     0, 82, periph_clk_enb_refcnt);
>  	clks[TEGRA114_CLK_DSIB] = clk;
>  
> -	/* emc mux */
> -	clk = clk_register_mux(NULL, "emc_mux", mux_pllmcp_clkm,
> -			       ARRAY_SIZE(mux_pllmcp_clkm),
> -			       CLK_SET_RATE_NO_REPARENT,
> -			       clk_base + CLK_SOURCE_EMC,
> -			       29, 3, 0, &emc_lock);
> -
> -	clk = tegra_clk_register_mc("mc", "emc_mux", clk_base + CLK_SOURCE_EMC,
> +	clk = tegra_clk_register_mc("mc", "emc", clk_base + CLK_SOURCE_EMC,
>  				    &emc_lock);
>  	clks[TEGRA114_CLK_MC] = clk;
>  
> @@ -1321,6 +1309,28 @@ static int tegra114_reset_deassert(unsigned long id)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_TEGRA124_CLK_EMC
> +static struct clk *tegra114_clk_src_onecell_get(struct of_phandle_args *clkspec,
> +						void *data)
> +{
> +	struct clk_hw *hw;
> +	struct clk *clk;
> +
> +	clk = of_clk_src_onecell_get(clkspec, data);
> +	if (IS_ERR(clk))
> +		return clk;
> +
> +	hw = __clk_get_hw(clk);
> +
> +	if (clkspec->args[0] == TEGRA114_CLK_EMC) {
> +		if (!tegra124_clk_emc_driver_available(hw))
> +			return ERR_PTR(-EPROBE_DEFER);
> +	}
> +
> +	return clk;
> +}
> +#endif
> +
>  static void __init tegra114_clock_init(struct device_node *np)
>  {
>  	struct device_node *node;
> @@ -1362,16 +1372,24 @@ static void __init tegra114_clock_init(struct device_node *np)
>  	tegra_audio_clk_init(clk_base, pmc_base, tegra114_clks,
>  			     tegra114_audio_plls,
>  			     ARRAY_SIZE(tegra114_audio_plls), 24000000);
> +
> +	tegra_clk_apply_init_table = tegra114_clock_apply_init_table;
> +

Is there any particular reason for moving this here? If not, omitting the change would simplify the patch a bit.

>  	tegra_super_clk_gen4_init(clk_base, pmc_base, tegra114_clks,
>  					&pll_x_params);
>  
>  	tegra_init_special_resets(1, tegra114_reset_assert,
>  				  tegra114_reset_deassert);
>  
> +#ifdef CONFIG_TEGRA124_CLK_EMC
> +	tegra_add_of_provider(np, tegra114_clk_src_onecell_get);
> +	clks[TEGRA114_CLK_EMC] = tegra124_clk_register_emc(clk_base, np,
> +							   &emc_lock);
> +#else
>  	tegra_add_of_provider(np, of_clk_src_onecell_get);
> -	tegra_register_devclks(devclks, ARRAY_SIZE(devclks));
> +#endif

tegra124_clk_register_emc and tegra124_clk_emc_driver_available have stub implementations when CONFIG_TEGRA124_CLK_EMC is not enabled, so it would be cleaner to just call them always.

>  
> -	tegra_clk_apply_init_table = tegra114_clock_apply_init_table;
> +	tegra_register_devclks(devclks, ARRAY_SIZE(devclks));
>  
>  	tegra_cpu_car_ops = &tegra114_cpu_car_ops;
>  }
>