linux-kernel - Re: [PATCH v2 2/4] phy: qcom-snps: Add SNPS USB PHY driver for QCOM based SOCs

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Date:   Tue, 24 Mar 2020 13:50:19 -0700
From:   Wesley Cheng <wcheng@...eaurora.org>
To:     Philipp Zabel <pza@...gutronix.de>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org, kishon@...com,
        robh+dt@...nel.org, mark.rutland@....com,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/4] phy: qcom-snps: Add SNPS USB PHY driver for QCOM
 based SOCs

Hi Philipp,

On 3/24/2020 2:49 AM, Philipp Zabel wrote:
> Hi Wesley,
> 
> On Mon, Mar 23, 2020 at 01:17:10PM -0700, Wesley Cheng wrote:
>> This adds the SNPS FemtoPHY driver used in QCOM SOCs.  There
>> are potentially multiple instances of this UTMI PHY on the
>> SOC, all which can utilize this driver.
>>
>> Signed-off-by: Wesley Cheng <wcheng@...eaurora.org>
>> ---
>>  drivers/phy/qualcomm/Kconfig             |  10 ++
>>  drivers/phy/qualcomm/Makefile            |   1 +
>>  drivers/phy/qualcomm/phy-qcom-snps-7nm.c | 294 +++++++++++++++++++++++++++++++
>>  3 files changed, 305 insertions(+)
>>  create mode 100644 drivers/phy/qualcomm/phy-qcom-snps-7nm.c
>>
> [...]
>> diff --git a/drivers/phy/qualcomm/phy-qcom-snps-7nm.c b/drivers/phy/qualcomm/phy-qcom-snps-7nm.c
>> new file mode 100644
>> index 0000000..8d4ba53
>> --- /dev/null
>> +++ b/drivers/phy/qualcomm/phy-qcom-snps-7nm.c
>> @@ -0,0 +1,294 @@
> [...]
>> +static int qcom_snps_hsphy_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct qcom_snps_hsphy *hsphy;
>> +	struct phy_provider *phy_provider;
>> +	struct phy *generic_phy;
>> +	struct resource *res;
>> +	int ret, i;
>> +	int num;
>> +
>> +	hsphy = devm_kzalloc(dev, sizeof(*hsphy), GFP_KERNEL);
>> +	if (!hsphy)
>> +		return -ENOMEM;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	hsphy->base = devm_ioremap_resource(dev, res);
>> +	if (IS_ERR(hsphy->base))
>> +		return PTR_ERR(hsphy->base);
>> +
>> +	hsphy->ref_clk = devm_clk_get(dev, "ref");
>> +	if (IS_ERR(hsphy->ref_clk)) {
>> +		ret = PTR_ERR(hsphy->ref_clk);
>> +		if (ret != -EPROBE_DEFER)
>> +			dev_err(dev, "failed to get ref clk, %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	hsphy->phy_reset = devm_reset_control_get_by_index(&pdev->dev, 0);
>> +	if (IS_ERR(hsphy->phy_reset)) {
>> +		dev_err(dev, "failed to get phy core reset\n");
>> +		return PTR_ERR(hsphy->phy_reset);
>> +	}
> 
> There is only a single reset specified, so there is no need for
> _by_index. Also please explicitly request exclusive reset control
> for this driver, I suggest:
> 
> 	hsphy->phy_reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
> 
> If you do want to prepare for future addition of other resets to the
> bindings (but if so, why not specify those right now?), you should add
> a reset-names property and request the reset control by id string
> instead.
> 
> regards
> Philipp
> 

Thanks for the feedback.  Sure, I will move to using
devm_reset_control_get_exclusive, as we won't be having multiple resets
for this particular PHY.  Will update a new patch series.

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