linux-kernel - Re: [RESEND PATCH v8 0/3] Add Intel ComboPhy driver

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Date:   Tue, 19 May 2020 11:56:41 +0800
From:   Dilip Kota <eswara.kota@...ux.intel.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        linux-kernel@...r.kernel.org, vkoul@...nel.org,
        devicetree@...r.kernel.org
Cc:     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: [RESEND PATCH v8 0/3] Add Intel ComboPhy driver


On 5/18/2020 9:49 PM, Kishon Vijay Abraham I wrote:
> Dilip,
>
> On 5/15/2020 1:43 PM, Dilip Kota wrote:
>> This patch series adds Intel ComboPhy driver, respective yaml schemas
>>
>> Changes on v8:
>>    As per PHY Maintainer's request add description in comments for doing
>>    register access through register map framework.
>>
>> Changes on v7:
>>    As per System control driver maintainer's inputs remove
>>      fwnode_to_regmap() definition and use device_node_get_regmap()
> Can you fix this warning and resend the patch?
> drivers/phy/intel/phy-intel-combo.c:229:6: warning: ‘cb_mode’ may be used
> uninitialized in this function [-Wmaybe-uninitialized]
>    ret = regmap_write(cbphy->hsiocfg, REG_COMBO_MODE(cbphy->bid), cb_mode);
>    ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/phy/intel/phy-intel-combo.c:204:24: note: ‘cb_mode’ was declared here
>    enum intel_combo_mode cb_mode;
>                          ^~~~~~~
I noticed this warning while preparing the patch.
It sounds like false warning because:
1.) "cb_mode" is initialized in the switch case based on the "mode = 
cbphy->phy_mode;"
2.) cbphy->phy_mode is initialized during the probe in 
"intel_cbphy_fwnode_parse()" with one of the 3 values.
PHY_PCIE_MODE, PHY_SATA_MODE, PHY_XPCS_MODE.
3.) There is no chance of "cbphy->phy_mode" having different value.
4.) And "cb_mode" will be initialized according to the "mode = 
cbphy->phy_mode;"
5.) Hence, there is no chance of "cb_mode" getting accessed uninitialized.

Regards,
Dilip
> Thanks
> Kishon
>>      
>> Changes on v6:
>>    Rebase patches on the latest maintainer's branch
>>    https://git.kernel.org/pub/scm/linux/kernel/git/kishon/linux-phy.git/?h=phy-for-5.7
>> Dilip Kota (3):
>>    dt-bindings: phy: Add PHY_TYPE_XPCS definition
>>    dt-bindings: phy: Add YAML schemas for Intel ComboPhy
>>    phy: intel: Add driver support for ComboPhy
>>
>>   .../devicetree/bindings/phy/intel,combo-phy.yaml   | 101 ++++
>>   drivers/phy/intel/Kconfig                          |  14 +
>>   drivers/phy/intel/Makefile                         |   1 +
>>   drivers/phy/intel/phy-intel-combo.c                | 632 +++++++++++++++++++++
>>   include/dt-bindings/phy/phy.h                      |   1 +
>>   5 files changed, 749 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/phy/intel,combo-phy.yaml
>>   create mode 100644 drivers/phy/intel/phy-intel-combo.c
>>