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

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Message-ID: <0ca57046-9bdc-69f3-3891-cac19cd57e8e@linux.intel.com>
Date:   Tue, 19 May 2020 13:25:31 +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 5/19/2020 1:17 PM, Kishon Vijay Abraham I wrote:
> Dilip,
>
> On 5/19/2020 9:26 AM, Dilip Kota wrote:
>> 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.
> Let's try to keep the compiler happy. Please fix this warning.
Sure, will fix it and send the patch series.
>
> Thanks
> Kishon