linux-kernel - Re: [PATCH v3] thermal: ti-soc-thermal: Remove unused variable 'val'

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Date:   Wed, 21 Apr 2021 13:36:30 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Lin Ruizhe <linruizhe@...wei.com>, rui.zhang@...el.com,
        edubezval@...il.com, j-keerthy@...com, amitk@...nel.org,
        eballetbo@...il.com, linux-pm@...r.kernel.org,
        linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] thermal: ti-soc-thermal: Remove unused variable 'val'


Hi Tony,

thanks for testing

  -- Daniel

On 21/04/2021 11:37, Tony Lindgren wrote:
> * Daniel Lezcano <daniel.lezcano@...aro.org> [210421 09:07]:
>> On 21/04/2021 10:49, Greg KH wrote:
>>> On Wed, Apr 21, 2021 at 04:42:56PM +0800, Lin Ruizhe wrote:
>>>> The variable 'val'in function ti_bandgap_restore_ctxt is
>>>> the register value of read bandgap registers. This function is to
>>>> restore the context. But there is no operation on the return value
>>>> of this register, so this block is redundant. Hulk robot scans this
>>>> warning.This commit remove the dead code.
>>>>
>>>> Reported-by: Hulk Robot <hulkci@...wei.com>
>>>> Fixes: b87ea759a4cc ("staging: omap-thermal: fix context restore function")
>>>> Signed-off-by: Lin Ruizhe <linruizhe@...wei.com>
>>>> ---
>>>> v3:
>>>> -Add Fixes tag and more accurate commit message in this patch.
>>>> v2:
>>>> -As suggest remove the whole unuesed block in fuction
>>>>  ti_bandgap_restore_ctxt
>>>>
>>>>  drivers/thermal/ti-soc-thermal/ti-bandgap.c | 4 ----
>>>>  1 file changed, 4 deletions(-)
>>>>
>>>> diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.c b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
>>>> index d81af89166d2..684ffb645aa9 100644
>>>> --- a/drivers/thermal/ti-soc-thermal/ti-bandgap.c
>>>> +++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
>>>> @@ -1142,14 +1142,10 @@ static int ti_bandgap_restore_ctxt(struct ti_bandgap *bgp)
>>>>  	for (i = 0; i < bgp->conf->sensor_count; i++) {
>>>>  		struct temp_sensor_registers *tsr;
>>>>  		struct temp_sensor_regval *rval;
>>>> -		u32 val = 0;
>>>>  
>>>>  		rval = &bgp->regval[i];
>>>>  		tsr = bgp->conf->sensors[i].registers;
>>>>  
>>>> -		if (TI_BANDGAP_HAS(bgp, COUNTER))
>>>> -			val = ti_bandgap_readl(bgp, tsr->bgap_counter);
>>>
>>> Are you sure that this hardware does not require this read to happen in
>>> order for it to work properly?
>>
>> Yes, initially we had the same concern but we were unable to find
>> anything specific in the history. The commit mentioned above removed the
>> user of the 'val' code but without removing this block of code.
>>
>> When looking at the current code, it really looks like an oversight.
> 
> Yes so it seems.
> 
>> There is nothing in the commit's changelog referring to a need of
>> reading the counter register but perhaps I'm wrong because I'm not sure
>> to understand correctly the changelog.
>>
>>> Lots of hardware does need this, have you tested this?
> 
> I just tested this on omap3 logicpd torpedo devkit that can do off during
> idle and reading /sys/class/thermal/thermal_zone0/temp works. So feel
> free to add:
> 
> Reviewed-by: Tony Lindgren <tony@...mide.com>
> Tested-by: Tony Lindgren <tony@...mide.com>

Thanks for testing


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