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Subject: Re: [PATCH] phy: intel: fix enum type mismatch warning
To:     Nathan Chancellor <natechancellor@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>
Cc:     Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com
References: <20200527134518.908624-1-arnd@arndb.de>
 <20200527164035.GA1073507@ubuntu-s3-xlarge-x86>
From:   Dilip Kota <eswara.kota@linux.intel.com>
Message-ID: <f9ac4d6b-95a2-3ac3-8aeb-d9a73801b4b5@linux.intel.com>
Date:   Thu, 28 May 2020 16:51:15 +0800
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On 5/28/2020 12:40 AM, Nathan Chancellor wrote:
> On Wed, May 27, 2020 at 03:45:06PM +0200, Arnd Bergmann wrote:
>> clang points out that a local variable is initialized with
>> an enum value of the wrong type:
>>
>> drivers/phy/intel/phy-intel-combo.c:202:34: error: implicit conversion from enumeration type 'enum intel_phy_mode' to different enumeration type 'enum intel_combo_mode' [-Werror,-Wenum-conversion]
>>          enum intel_combo_mode cb_mode = PHY_PCIE_MODE;
>>                                ~~~~~~~   ^~~~~~~~~~~~~
>>
>>  From reading the code, it seems that this was not only the
>> wrong type, but not even supposed to be a code path that can
>> happen in practice.
>>
>> Change the code to have no default phy mode but instead return an
>> error for invalid input.
>>
>> Fixes: ac0a95a3ea78 ("phy: intel: Add driver support for ComboPhy")
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>>   drivers/phy/intel/phy-intel-combo.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/phy/intel/phy-intel-combo.c b/drivers/phy/intel/phy-intel-combo.c
>> index c2a35be4cdfb..04f7b0d08742 100644
>> --- a/drivers/phy/intel/phy-intel-combo.c
>> +++ b/drivers/phy/intel/phy-intel-combo.c
>> @@ -199,7 +199,7 @@ static int intel_cbphy_pcie_dis_pad_refclk(struct intel_cbphy_iphy *iphy)
>>   
>>   static int intel_cbphy_set_mode(struct intel_combo_phy *cbphy)
>>   {
>> -	enum intel_combo_mode cb_mode = PHY_PCIE_MODE;
>> +	enum intel_combo_mode cb_mode;
>>   	enum aggregated_mode aggr = cbphy->aggr_mode;
>>   	struct device *dev = cbphy->dev;
>>   	enum intel_phy_mode mode;
>> @@ -224,6 +224,8 @@ static int intel_cbphy_set_mode(struct intel_combo_phy *cbphy)
>>   
>>   		cb_mode = SATA0_SATA1_MODE;
>>   		break;
>> +	default:
>> +		return -EINVAL;
>>   	}
>>   
>>   	ret = regmap_write(cbphy->hsiocfg, REG_COMBO_MODE(cbphy->bid), cb_mode);
>> -- 
>> 2.26.2
>>
> I sent an almost identical patch:
>
> https://lore.kernel.org/lkml/20200523035043.3305846-1-natechancellor@gmail.com/
>
> I left out the default case since clang warns when a switch on an enum
> does not handle all the values (compile time scream) versus a run time
> scream like yours.
>
> I don't have a preference for either so:
>
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Thanks for fixing it. I wrongly initiated it with PHY_PCIE_MODE instead 
of PCIE0_PCIE1_MODE to fix the compiler warnings. (On real time use 
case, cb_mode gets initialized with one of the switch case values, it 
never hits the default case, so I didn't add the default case.)

This patch looks good to fix the warnings.
Reviewed-by: Dilip Kota <eswara.kota@linux.intel.com>

Regards,
Dilip