linux-kernel - Re: [PATCH v7 3/3] phy: intel: Add driver support for ComboPhy

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Date:   Tue, 5 May 2020 15:54:40 +0800
From:   Dilip Kota <eswara.kota@...ux.intel.com>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     linux-kernel@...r.kernel.org, kishon@...com,
        devicetree@...r.kernel.org, lee.jones@...aro.org, arnd@...db.de,
        robh@...nel.org, andriy.shevchenko@...el.com,
        cheol.yong.kim@...el.com, chuanhua.lei@...ux.intel.com,
        qi-ming.wu@...el.com, yixin.zhu@...el.com
Subject: Re: [PATCH v7 3/3] phy: intel: Add driver support for ComboPhy


On 5/5/2020 1:21 PM, Vinod Koul wrote:
> On 04-05-20, 17:32, Dilip Kota wrote:
>> On 5/4/2020 5:20 PM, Vinod Koul wrote:
>>> On 04-05-20, 16:26, Dilip Kota wrote:
>>>> On 5/4/2020 3:29 PM, Vinod Koul wrote:
>>>>> On 30-04-20, 15:15, Dilip Kota wrote:
>>>>>
>>>>>> +					  u32 mask, u32 val)
>>>>>> +{
>>>>>> +	u32 reg_val;
>>>>>> +
>>>>>> +	reg_val = readl(base + reg);
>>>>>> +	reg_val &= ~mask;
>>>>>> +	reg_val |= FIELD_PREP(mask, val);
>>>>>> +	writel(reg_val, base + reg);
>>>>> bypassing regmap here... why?
>>>> It is not regmap address, one of the below two addresses are passed to this
>>>> function.
>>> okay, perhaps add a comment somewhere that regmap is not used for this
>>> base?
>> I dont see a need of adding a comment, describing don't do regmap here.
> Driver uses regmap except here, which seems odd hence explanation
> required for this.
During the driver Probe, the register phandles are stored in regmap 
datatype variables and PHY core addresses are stored in iomem datatype.
Since then, regmap access is performed for the regmap datatype variables 
and readl/writel access is performed on the iomem datatype variables. 
And nowhere in the driver iomem datatype address are converted to regmap 
address and performed regmap access.

Driver is not doing any 'regmap_init' on any physical address. Driver is 
getting the register address phandle from the device tree node and 
performing the regmap access.
ret = fwnode_property_get_reference_args(fwnode, "intel,syscfg", NULL, 
1, 0, &ref);
[...]
cbphy->syscfg = device_node_to_regmap(to_of_node(ref.fwnode));

[...]
ret = fwnode_property_get_reference_args(fwnode, "intel,hsio", NULL, 1, 
0, &ref);
[...]

cbphy->hsiocfg = device_node_to_regmap(to_of_node(ref.fwnode));

[...]
cbphy->app_base = devm_platform_ioremap_resource_byname(pdev, "app");
  [...]
cbphy->cr_base = devm_platform_ioremap_resource_byname(pdev, "core");

The DT parsing logic in the driver is explaining why the PHY driver 
should do regmap access and to whom should be done. For this reason i am 
a bit puzzled to what more is needed to explain in the comments and 
where to add it.
Please let me know your view.

Regards,
Dilip