linux-kernel - 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 21:25:40 +0800
From: Jie Luo <quic_luoj@...cinc.com>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>, <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 1/3/2024 5:48 PM, Bryan O'Donoghue wrote:
> 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;

Thanks for the comments, will update it.
> 
> 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

Ok, thanks bod for the comments to improve the code.

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