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Date:   Fri, 28 Oct 2022 16:02:25 +0530
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Subject: Re: [PATCH v3 2/3] phy: ti: gmii-sel: Update methods for fetching and
 using qsgmii main port
To:     Roger Quadros <rogerq@kernel.org>
References: <20221026074532.109220-1-s-vadapalli@ti.com>
 <20221026074532.109220-3-s-vadapalli@ti.com>
 <ad852357-98a3-b8b9-e9eb-d65c28947ed5@kernel.org>
Content-Language: en-US
From:   Siddharth Vadapalli <s-vadapalli@ti.com>
In-Reply-To: <ad852357-98a3-b8b9-e9eb-d65c28947ed5@kernel.org>
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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@ti.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.

Regards,
Siddharth.