netdev - Re: [PATCH v4 2/5] net: mdio: ipq4019: enable the SoC uniphy clocks for ipq5332 platform

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Date: Wed, 3 Jan 2024 09:48:15 +0000
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Luo Jie <quic_luoj@...cinc.com>, agross@...nel.org, andersson@...nel.org,
 konrad.dybcio@...aro.org, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, andrew@...n.ch,
 hkallweit1@...il.com, linux@...linux.org.uk, robert.marko@...tura.hr
Cc: linux-arm-msm@...r.kernel.org, netdev@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 quic_srichara@...cinc.com
Subject: Re: [PATCH v4 2/5] net: mdio: ipq4019: enable the SoC uniphy clocks
 for ipq5332 platform

On 25/12/2023 08:44, Luo Jie wrote:
> On the platform ipq5332, the related SoC uniphy GCC clocks need
> to be enabled for making the MDIO slave devices accessible.
> 
> These UNIPHY clocks are from the SoC platform GCC clock provider,
> which are enabled for the connected PHY devices working.
> 
> Signed-off-by: Luo Jie <quic_luoj@...cinc.com>
> ---
>   drivers/net/mdio/mdio-ipq4019.c | 75 ++++++++++++++++++++++++++++-----
>   1 file changed, 64 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/mdio/mdio-ipq4019.c b/drivers/net/mdio/mdio-ipq4019.c
> index 5273864fabb3..e24b0e688b10 100644
> --- a/drivers/net/mdio/mdio-ipq4019.c
> +++ b/drivers/net/mdio/mdio-ipq4019.c
> @@ -35,15 +35,36 @@
>   /* MDIO clock source frequency is fixed to 100M */
>   #define IPQ_MDIO_CLK_RATE	100000000
>   
> +/* SoC UNIPHY fixed clock */
> +#define IPQ_UNIPHY_AHB_CLK_RATE	100000000
> +#define IPQ_UNIPHY_SYS_CLK_RATE	24000000
> +
>   #define IPQ_PHY_SET_DELAY_US	100000
>   
>   /* Maximum SOC PCS(uniphy) number on IPQ platform */
>   #define ETH_LDO_RDY_CNT				3
>   
> +enum mdio_clk_id {
> +	MDIO_CLK_MDIO_AHB,
> +	MDIO_CLK_UNIPHY0_AHB,
> +	MDIO_CLK_UNIPHY0_SYS,
> +	MDIO_CLK_UNIPHY1_AHB,
> +	MDIO_CLK_UNIPHY1_SYS,
> +	MDIO_CLK_CNT
> +};
> +
>   struct ipq4019_mdio_data {
>   	void __iomem *membase;
>   	void __iomem *eth_ldo_rdy[ETH_LDO_RDY_CNT];
> -	struct clk *mdio_clk;
> +	struct clk *clk[MDIO_CLK_CNT];
> +};
> +
> +static const char *const mdio_clk_name[] = {
> +	"gcc_mdio_ahb_clk",
> +	"uniphy0_ahb",
> +	"uniphy0_sys",
> +	"uniphy1_ahb",
> +	"uniphy1_sys"
>   };
>   
>   static int ipq4019_mdio_wait_busy(struct mii_bus *bus)
> @@ -209,14 +230,43 @@ static int ipq4019_mdio_write_c22(struct mii_bus *bus, int mii_id, int regnum,
>   static int ipq_mdio_reset(struct mii_bus *bus)
>   {
>   	struct ipq4019_mdio_data *priv = bus->priv;
> -	int ret;
> +	unsigned long rate;
> +	int ret, index;
>   
> -	/* Configure MDIO clock source frequency if clock is specified in the device tree */
> -	ret = clk_set_rate(priv->mdio_clk, IPQ_MDIO_CLK_RATE);
> -	if (ret)
> -		return ret;
> +	/* For the platform ipq5332, there are two SoC uniphies available
> +	 * for connecting with ethernet PHY, the SoC uniphy gcc clock
> +	 * should be enabled for resetting the connected device such
> +	 * as qca8386 switch, qca8081 PHY or other PHYs effectively.
> +	 *
> +	 * Configure MDIO/UNIPHY clock source frequency if clock instance
> +	 * is specified in the device tree.
> +	 */
> +	for (index = MDIO_CLK_MDIO_AHB; index < MDIO_CLK_CNT; index++) {

you could do a

if (!priv->clk[index])
	continue;

here and save a few cycles executing code for absent clocks. ipq6018 has 
just 1/5 of the clocks you are checking for here.

Better still capture the number of clocks you find in probe() in a 
variable priv->num_clocks and only step through the array

for (i = 0; i < priv->num_clocks; i++) {}

---
bod