Re: [PATCH net-next v2 8/9] net: stmmac: qcom-ethqos: add per-platform NOC clock voting

[Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>]

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> Some SoCs gate the EMAC's path to the System NOC behind dedicated clocks
> that must be enabled before the DMA can reach memory. Add
> ethqos_noc_clk_cfg and the corresponding fields in the driver-data and
> runtime structs so each compatible can declare its own set with per-clock
> rates.  The clocks are acquired during probe and enabled/disabled
> alongside the existing link clock in ethqos_clks_config().
> 
> No functional change for existing compatibles. This will help us when
> we add support for Shikra.
> 
> Signed-off-by: Mohd Ayaan Anwar <mohd.anwar@oss.qualcomm.com>
> ---
>  .../ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c    | 106 +++++++++++++++++++++
>  1 file changed, 106 insertions(+)
> 

[...]

>  static u32 rgmii_readl(struct qcom_ethqos *ethqos, unsigned int offset)
> @@ -689,15 +703,51 @@ static int ethqos_mac_finish_serdes(struct net_device *ndev, void *priv,
>  static int ethqos_clks_config(void *priv, bool enabled)
>  {
>  	struct qcom_ethqos *ethqos = priv;
> +	unsigned int i;
>  	int ret = 0;
>  
>  	if (enabled) {
> +		if (ethqos->num_noc_clks) {
> +			ret = dev_pm_opp_set_rate(&ethqos->pdev->dev,
> +						  ethqos->noc_clk_rates[0]);

assuming the first clock is always an OPP device seems a bit fragile to me.
Can we find a way to enforce it? (e.g. have a dedicated clk_bulk_data struct
for it).

> +			if (ret) {
> +				dev_err(&ethqos->pdev->dev,
> +					"NOC OPP rate set failed: %d\n", ret);
> +				return ret;
> +			}
> +
> +			for (i = 1; i < ethqos->num_noc_clks; i++) {
> +				ret = clk_set_rate(ethqos->noc_clks[i].clk,
> +						   ethqos->noc_clk_rates[i]);
> +				if (ret) {
> +					dev_err(&ethqos->pdev->dev,
> +						"NOC clock rate set failed: %d\n", ret);
> +					dev_pm_opp_set_rate(&ethqos->pdev->dev, 0);
> +					return ret;
> +				}
> +			}
> +		}
> +
>  		ret = clk_prepare_enable(ethqos->link_clk);
>  		if (ret) {
>  			dev_err(&ethqos->pdev->dev, "link_clk enable failed\n");
> +			if (ethqos->num_noc_clks)
> +				dev_pm_opp_set_rate(&ethqos->pdev->dev, 0);
>  			return ret;
>  		}
>  
> +		if (ethqos->num_noc_clks) {
> +			ret = clk_bulk_prepare_enable(ethqos->num_noc_clks,
> +						      ethqos->noc_clks);
> +			if (ret) {
> +				dev_err(&ethqos->pdev->dev,
> +					"NOC clocks enable failed: %d\n", ret);
> +				clk_disable_unprepare(ethqos->link_clk);
> +				dev_pm_opp_set_rate(&ethqos->pdev->dev, 0);
> +				return ret;
> +			}
> +		}
> +
>  		/* Enable functional clock to prevent DMA reset to timeout due
>  		 * to lacking PHY clock after the hardware block has been power
>  		 * cycled. The actual configuration will be adjusted once
> @@ -706,7 +756,12 @@ static int ethqos_clks_config(void *priv, bool enabled)
>  		qcom_ethqos_set_sgmii_loopback(ethqos, true);
>  		ethqos_set_func_clk_en(ethqos);
>  	} else {
> +		if (ethqos->num_noc_clks)
> +			clk_bulk_disable_unprepare(ethqos->num_noc_clks,
> +						   ethqos->noc_clks);
>  		clk_disable_unprepare(ethqos->link_clk);
> +		if (ethqos->num_noc_clks)
> +			dev_pm_opp_set_rate(&ethqos->pdev->dev, 0);
>  	}
>  
>  	return ret;
> @@ -734,6 +789,51 @@ static void ethqos_ptp_clk_freq_config(struct stmmac_priv *priv)
>  	netdev_dbg(priv->dev, "PTP rate %lu\n", plat_dat->clk_ptp_rate);
>  }
>  
> +static void qcom_ethqos_noc_opp_cleanup(void *dev)
> +{
> +	dev_pm_opp_set_rate(dev, 0);
> +}
> +
> +/* Some SoCs gate NOC access behind dedicated clocks. Acquire them here
> + * so ethqos_clks_config() can enable/disable them at runtime. The OPP
> + * table is used to propagate the required VDD_CX performance state via
> + * dev_pm_opp_set_rate().
> + */
> +static int qcom_ethqos_init_noc_clks(struct qcom_ethqos *ethqos,
> +				     const struct ethqos_emac_driver_data *data)
> +{
> +	struct device *dev = &ethqos->pdev->dev;
> +	unsigned int i;
> +	int ret;
> +
> +	if (!data->num_noc_clks)
> +		return 0;
> +
> +	for (i = 0; i < data->num_noc_clks; i++) {
> +		ethqos->noc_clks[i].id = data->noc_clk_cfg[i].id;
> +		ethqos->noc_clk_rates[i] = data->noc_clk_cfg[i].rate;
> +	}
> +	ethqos->num_noc_clks = data->num_noc_clks;
> +
> +	ret = devm_clk_bulk_get(dev, ethqos->num_noc_clks, ethqos->noc_clks);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to get NOC clocks\n");
> +
> +	ret = devm_pm_opp_set_clkname(dev, data->noc_clk_cfg[0].id);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to set OPP clock name\n");
> +
> +	ret = devm_pm_opp_of_add_table(dev);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to add OPP table\n");
> +
> +	ret = dev_pm_opp_set_rate(dev, data->noc_clk_cfg[0].rate);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to set initial NOC OPP rate\n");
> +
> +	return devm_add_action_or_reset(dev, qcom_ethqos_noc_opp_cleanup, dev);
> +}
> +
>  static int qcom_ethqos_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> @@ -795,6 +895,12 @@ static int qcom_ethqos_probe(struct platform_device *pdev)
>  	ethqos->has_emac_ge_3 = data->has_emac_ge_3;
>  	ethqos->needs_sgmii_loopback = data->needs_sgmii_loopback;
>  
> +	if (data->num_noc_clks) {

I guess you can drop this check since it is already done in
qcom_ethqos_init_noc_clks(), right?

Regards,
Lorenzo

> +		ret = qcom_ethqos_init_noc_clks(ethqos, data);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	ethqos->link_clk = devm_clk_get(dev, data->link_clk_name ?: "rgmii");
>  	if (IS_ERR(ethqos->link_clk))
>  		return dev_err_probe(dev, PTR_ERR(ethqos->link_clk),
> 
> -- 
> 2.34.1
> 
> 

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