linux-kernel - Re: [PATCH v3 2/3] phy: ti: gmii-sel: Update methods for fetching and using qsgmii main port

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Message-ID: <7f85cf3e-e04d-c4b6-46c8-7125d76cd599@kernel.org>
Date:   Fri, 28 Oct 2022 13:42:11 +0300
From:   Roger Quadros <rogerq@...nel.org>
To:     Siddharth Vadapalli <s-vadapalli@...com>
Cc:     robh+dt@...nel.org, lee@...nel.org, krzysztof.kozlowski@...aro.org,
        krzysztof.kozlowski+dt@...aro.org, kishon@...nel.org,
        vkoul@...nel.org, dan.carpenter@...cle.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-phy@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 2/3] phy: ti: gmii-sel: Update methods for fetching and
 using qsgmii main port



On 28/10/2022 13:32, Siddharth Vadapalli wrote:
> Hello Roger,
> 
> On 28/10/22 15:53, Roger Quadros wrote:
>> Hi Siddharth,
>>
>> On 26/10/2022 10:45, Siddharth Vadapalli wrote:
>>> The number of QSGMII main ports are specific to the device. TI's J7200 for
>>> which the QSGMII main port property is fetched from the device-tree has
>>> only one QSGMII main port. However, devices like TI's J721e support up to
>>> two QSGMII main ports. Thus, the existing methods for fetching and using
>>> the QSGMII main port are not scalable.
>>>
>>> Update the existing methods for handling the QSGMII main ports and its
>>> associated requirements to make it scalable for future devices.
>>>
>>> Signed-off-by: Siddharth Vadapalli <s-vadapalli@...com>
>>> ---
>>>  drivers/phy/ti/phy-gmii-sel.c | 29 ++++++++++++++++++++++-------
>>>  1 file changed, 22 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/phy/ti/phy-gmii-sel.c b/drivers/phy/ti/phy-gmii-sel.c
>>> index 0bcfd6d96b4d..c8f30d2e1f46 100644
>>> --- a/drivers/phy/ti/phy-gmii-sel.c
>>> +++ b/drivers/phy/ti/phy-gmii-sel.c
>>> @@ -50,6 +50,7 @@ struct phy_gmii_sel_soc_data {
>>>  	const struct reg_field (*regfields)[PHY_GMII_SEL_LAST];
>>>  	bool use_of_data;
>>>  	u64 extra_modes;
>>> +	u32 num_qsgmii_main_ports;
>>>  };
>>>  
>>>  struct phy_gmii_sel_priv {
>>> @@ -213,6 +214,8 @@ struct phy_gmii_sel_soc_data phy_gmii_sel_cpsw5g_soc_j7200 = {
>>>  	.use_of_data = true,
>>>  	.regfields = phy_gmii_sel_fields_am654,
>>>  	.extra_modes = BIT(PHY_INTERFACE_MODE_QSGMII),
>>> +	.num_ports = 4,
>>> +	.num_qsgmii_main_ports = 1,
>>>  };
>>>  
>>>  static const struct of_device_id phy_gmii_sel_id_table[] = {
>>> @@ -378,11 +381,13 @@ static int phy_gmii_sel_init_ports(struct phy_gmii_sel_priv *priv)
>>>  static int phy_gmii_sel_probe(struct platform_device *pdev)
>>>  {
>>>  	struct device *dev = &pdev->dev;
>>> +	const struct phy_gmii_sel_soc_data *soc_data;
>>>  	struct device_node *node = dev->of_node;
>>>  	const struct of_device_id *of_id;
>>>  	struct phy_gmii_sel_priv *priv;
>>>  	u32 main_ports = 1;
>>>  	int ret;
>>> +	u32 i;
>>>  
>>>  	of_id = of_match_node(phy_gmii_sel_id_table, pdev->dev.of_node);
>>>  	if (!of_id)
>>> @@ -394,16 +399,26 @@ static int phy_gmii_sel_probe(struct platform_device *pdev)
>>>  
>>>  	priv->dev = &pdev->dev;
>>>  	priv->soc_data = of_id->data;
>>> +	soc_data = priv->soc_data;
>>>  	priv->num_ports = priv->soc_data->num_ports;
>>> -	of_property_read_u32(node, "ti,qsgmii-main-ports", &main_ports);
>>> +	priv->qsgmii_main_ports = 0;
>>> +
>>>  	/*
>>> -	 * Ensure that main_ports is within bounds. If the property
>>> -	 * ti,qsgmii-main-ports is not mentioned, or the value mentioned
>>> -	 * is out of bounds, default to 1.
>>> +	 * Based on the compatible, try to read the appropriate number of
>>> +	 * QSGMII main ports from the "ti,qsgmii-main-ports" property from
>>> +	 * the device-tree node.
>>>  	 */
>>> -	if (main_ports < 1 || main_ports > 4)
>>> -		main_ports = 1;
>>> -	priv->qsgmii_main_ports = PHY_GMII_PORT(main_ports);
>>> +	for (i = 0; i < soc_data->num_qsgmii_main_ports; i++) {
>>> +		of_property_read_u32_index(node, "ti,qsgmii-main-ports", i, &main_ports);
>>> +		/*
>>> +		 * Ensure that main_ports is within bounds.
>>> +		 */
>>> +		if (main_ports < 1 || main_ports > soc_data->num_ports) {
>>> +			dev_err(dev, "Invalid qsgmii main port provided\n");
>>
>> nit: This message is a bit misleading if the property does not exist in DT.
>>
>> How about just "Invalid ti,qsgmii-main-ports"
> 
> Thank you for reviewing the patch. The variable "main_ports" has been
> initialized to 1 at the top. Thus, the only way the error condition is
> entered is if "ti,qsgmii-main-ports" is mentioned in the device-tree
> with an invalid value. If "ti,qsgmii-main-ports" is not mentioned in the
> device-tree, then "main_ports" continues being 1, since the function
> "of_property_read_u32_index()" does not modify "main_ports" if
> "ti,qsgmii-main-ports" is not present in the device-tree. Thus, in this
> case, the error condition isn't reached.

You are right. No need to change the message in that case.

cheers,
-roger