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Message-ID: <3137049f-eac8-4522-ad2e-b2b0d3537239@foss.st.com>
Date: Mon, 13 May 2024 17:11:52 +0200
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Subject: Re: [PATCH v2 05/11] net: stmmac: dwmac-stm32: update config
 management for phy wo cristal
To: Marek Vasut <marex@denx.de>, "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
        Paolo
 Abeni <pabeni@redhat.com>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley
	<conor+dt@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre
 Torgue <alexandre.torgue@foss.st.com>,
        Richard Cochran
	<richardcochran@gmail.com>,
        Jose Abreu <joabreu@synopsys.com>,
        Liam Girdwood
	<lgirdwood@gmail.com>, Mark Brown <broonie@kernel.org>
CC: <netdev@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>
References: <20240426125707.585269-1-christophe.roullier@foss.st.com>
 <20240426125707.585269-6-christophe.roullier@foss.st.com>
 <b790f34e-8bfb-44f6-869d-798508008483@denx.de>
Content-Language: en-US
From: Christophe ROULLIER <christophe.roullier@foss.st.com>
In-Reply-To: <b790f34e-8bfb-44f6-869d-798508008483@denx.de>
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On 4/26/24 17:37, Marek Vasut wrote:
> On 4/26/24 2:57 PM, Christophe Roullier wrote:
>> Some cleaning because some Ethernet PHY configs do not need to add
>> st,ext-phyclk property.
>> Change print info message "No phy clock provided" only when debug.
>>
>> Signed-off-by: Christophe Roullier <christophe.roullier@foss.st.com>
>> ---
>>   .../net/ethernet/stmicro/stmmac/dwmac-stm32.c | 27 ++++++++++---------
>>   1 file changed, 14 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c 
>> b/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
>> index 7529a8d15492..e648c4e790a7 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
>> @@ -55,17 +55,17 @@
>>    *|         |        |      25MHz    |        50MHz 
>> |                  |
>>    * 
>> ---------------------------------------------------------------------------
>>    *|  MII    |     -   |     eth-ck    |          n/a |      
>> n/a        |
>> - *|         |        | st,ext-phyclk | |             |
>> + *|         |        |                 | |             |
>>    * 
>> ---------------------------------------------------------------------------
>>    *|  GMII   |     -   |     eth-ck    |          n/a |      
>> n/a        |
>> - *|         |        | st,ext-phyclk | |             |
>> + *|         |        |               | |             |
>>    * 
>> ---------------------------------------------------------------------------
>>    *| RGMII   |     -   |     eth-ck    |          n/a |      
>> eth-ck      |
>> - *|         |        | st,ext-phyclk |                    | 
>> st,eth-clk-sel or|
>> + *|         |        |               |                    | 
>> st,eth-clk-sel or|
>>    *|         |        |               |                    | 
>> st,ext-phyclk    |
>>    * 
>> ---------------------------------------------------------------------------
>>    *| RMII    |     -   |     eth-ck    |        eth-ck |      
>> n/a        |
>> - *|         |        | st,ext-phyclk | st,eth-ref-clk-sel 
>> |             |
>> + *|         |        |               | st,eth-ref-clk-sel 
>> |             |
>>    *|         |        |               | or st,ext-phyclk 
>> |             |
>>    * 
>> ---------------------------------------------------------------------------
>>    *
>> @@ -174,23 +174,22 @@ static int stm32mp1_set_mode(struct 
>> plat_stmmacenet_data *plat_dat)
>>       dwmac->enable_eth_ck = false;
>>       switch (plat_dat->mac_interface) {
>>       case PHY_INTERFACE_MODE_MII:
>> -        if (clk_rate == ETH_CK_F_25M && dwmac->ext_phyclk)
>> +        if (clk_rate == ETH_CK_F_25M)
>
> I see two problems here.
>
> First, according to the table above, in MII mode, clk_rate cannot be 
> anything else but 25 MHz, so the (clk_rate == ETH_CK_F_25M) condition 
> is always true. Why not drop that condition ?
Not agree, there is also "Normal" case MII (MII with quartz/cristal) 
(first column in the table above), so need to keep this test to check 
clk_rate 25MHz.
>
> The "dwmac->ext_phyclk" means "Ethernet PHY have no crystal", which 
> means the clock are provided by the STM32 RCC clock IP instead, which 
> means if the dwmac->ext_phyclk is true, dwmac->enable_eth_ck should be 
> set to true, because dwmac->enable_eth_ck controls the enablement of 
> these STM32 clock IP generated clock.
Right
>
> Second, as far as I understand it, there is no way to operate this IP 
> with external clock in MII mode, so this section should always be only:
>
> dwmac->enable_eth_ck = true;
Not for case "Normal" MII :-)
>
>>               dwmac->enable_eth_ck = true;
>>           val = dwmac->ops->pmcsetr.eth1_selmii;
>>           pr_debug("SYSCFG init : PHY_INTERFACE_MODE_MII\n");
>>           break;
>>       case PHY_INTERFACE_MODE_GMII:
>>           val = SYSCFG_PMCR_ETH_SEL_GMII;
>> -        if (clk_rate == ETH_CK_F_25M &&
>> -            (dwmac->eth_clk_sel_reg || dwmac->ext_phyclk)) {
>> +        if (clk_rate == ETH_CK_F_25M)
>>               dwmac->enable_eth_ck = true;
>> -            val |= dwmac->ops->pmcsetr.eth1_clk_sel;
>> -        }
>>           pr_debug("SYSCFG init : PHY_INTERFACE_MODE_GMII\n");
>>           break;
>>       case PHY_INTERFACE_MODE_RMII:
>>           val = dwmac->ops->pmcsetr.eth1_sel_rmii | 
>> dwmac->ops->pmcsetr.eth2_sel_rmii;
>> -        if ((clk_rate == ETH_CK_F_25M || clk_rate == ETH_CK_F_50M) &&
>> +        if (clk_rate == ETH_CK_F_25M)
>> +            dwmac->enable_eth_ck = true;
>> +        if (clk_rate == ETH_CK_F_50M &&
>>               (dwmac->eth_ref_clk_sel_reg || dwmac->ext_phyclk)) {
>
> This doesn't seem to be equivalent change to the previous code . Here, 
> if the clock frequency is 25 MHz, the clock are unconditionally 
> enabled. Before, the code enabled the clock only if clock frequency 
> was 25 MHz AND one of the "dwmac->eth_ref_clk_sel_reg" or 
> "dwmac->ext_phyclk" was set (i.e. clock provided by SoC RCC clock IP).

You are right, but in STM32MP15/MP13 reference manual it is write that 
we need to update SYSCFG (SYSCFG_PMCSETR) register only in "Ethernet 
50MHz RMII clock selection":

Bit 17 ETH_REF_CLK_SEL: Ethernet 50MHz RMII clock selection.

     Set by software.

       0: Writing '0' has no effect, reading '0' means External clock is 
used. Need selection of AFMux. Could be used with all PHY

       1: Writing '1' set this bit, reading '1' means Internal clock 
ETH_CLK1 from RCC is used regardless AFMux. Could be used only with RMII PHY

>
> I think it might make this code easier if you drop all of the 
> frequency test conditionals, which aren't really all that useful, and 
> only enable the clock if either dwmac->ext_phyclk / 
> dwmac->eth_clk_sel_reg / dwmac->eth_ref_clk_sel_reg is set , because 
> effectively what this entire convoluted code is implementing is "if 
> (clock supplied by clock IP i.e. RCC) enable the clock()" *, right ?
>
> * And it is also toggling the right clock mux bit in PMCSETR.
>
> So, for MII this would be plain:
> dwmac->enable_eth_ck = true;
>
> For GMII/RGMII this would be:
> if (dwmac->ext_phyclk || dwmac->eth_clk_sel_reg)
>   dwmac->enable_eth_ck = true;
>
> For RMII this would be:
> if (dwmac->ext_phyclk || dwmac->eth_ref_clk_sel_reg)
>   dwmac->enable_eth_ck = true;
>
> Maybe the clock frequency validation can be retained, but done 
> separately?
As explained previously, need to keep check of clock frequency in this test.
>
>>               dwmac->enable_eth_ck = true;
>>               val |= dwmac->ops->pmcsetr.eth1_ref_clk_sel;
>> @@ -203,7 +202,9 @@ static int stm32mp1_set_mode(struct 
>> plat_stmmacenet_data *plat_dat)
>>       case PHY_INTERFACE_MODE_RGMII_RXID:
>>       case PHY_INTERFACE_MODE_RGMII_TXID:
>>           val = dwmac->ops->pmcsetr.eth1_sel_rgmii | 
>> dwmac->ops->pmcsetr.eth2_sel_rgmii;
>> -        if ((clk_rate == ETH_CK_F_25M || clk_rate == ETH_CK_F_125M) &&
>> +        if (clk_rate == ETH_CK_F_25M)
>> +            dwmac->enable_eth_ck = true;
>> +        if (clk_rate == ETH_CK_F_125M &&
>>               (dwmac->eth_clk_sel_reg || dwmac->ext_phyclk)) {
>>               dwmac->enable_eth_ck = true;
>>               val |= dwmac->ops->pmcsetr.eth1_clk_sel;
>> @@ -219,7 +220,7 @@ static int stm32mp1_set_mode(struct 
>> plat_stmmacenet_data *plat_dat)
>>       }
>>         /* Need to update PMCCLRR (clear register) */
>> -    regmap_write(dwmac->regmap, reg + dwmac->ops->syscfg_clr_off,
>> +    regmap_write(dwmac->regmap, dwmac->ops->syscfg_clr_off,
>>                dwmac->mode_mask);
>>         /* Update PMCSETR (set register) */
>> @@ -328,7 +329,7 @@ static int stm32mp1_parse_data(struct stm32_dwmac 
>> *dwmac,
>>       /*  Get ETH_CLK clocks */
>>       dwmac->clk_eth_ck = devm_clk_get(dev, "eth-ck");
>>       if (IS_ERR(dwmac->clk_eth_ck)) {
>> -        dev_info(dev, "No phy clock provided...\n");
>> +        dev_dbg(dev, "No phy clock provided...\n");
>>           dwmac->clk_eth_ck = NULL;
>>       }