RE: [PATCH v4 3/3] timer/exynos4210_mct: Remove redundant statement in exynos4210_mct_write()

["Chenqun (kuhn)" <kuhn.chenqun@huawei.com>]

>-----Original Message-----
>From: Laurent Vivier [mailto:laurent@vivier.eu]
>Sent: Tuesday, March 24, 2020 6:59 PM
>To: Chenqun (kuhn) <kuhn.chenqun@huawei.com>; qemu-devel@nongnu.org;
>qemu-trivial@nongnu.org
>Cc: Zhanghailiang <zhang.zhanghailiang@huawei.com>; philmd@redhat.com;
>Euler Robot <euler.robot@huawei.com>; Igor Mitsyanko
><i.mitsyanko@gmail.com>; Peter Maydell <peter.maydell@linaro.org>
>Subject: Re: [PATCH v4 3/3] timer/exynos4210_mct: Remove redundant
>statement in exynos4210_mct_write()
>
>Le 24/03/2020 à 09:22, Chen Qun a écrit :
>> Clang static code analyzer show warning:
>> hw/timer/exynos4210_mct.c:1370:9: warning: Value stored to 'index' is never
>read
>>         index = GET_L_TIMER_CNT_REG_IDX(offset, lt_i);
>>         ^       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> hw/timer/exynos4210_mct.c:1399:9: warning: Value stored to 'index' is never
>read
>>         index = GET_L_TIMER_CNT_REG_IDX(offset, lt_i);
>>         ^       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> hw/timer/exynos4210_mct.c:1441:9: warning: Value stored to 'index' is never
>read
>>         index = GET_L_TIMER_CNT_REG_IDX(offset, lt_i);
>>         ^       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>It would be interesting to understand why we need the index for these registers
>in exynos4210_mct_read() and not in exynos4210_mct_write().
>
I think the index can also be used in exynos4210_mct_write(), but the original author used a more obvious reg name instead of it.

The obvious reg name:
case L0_TCNTB: case L1_TCNTB:
           reg name is :  L_REG_CNT_TCNTB 

case L0_ICNTB: case L1_ICNTB:
           reg name is :   L_REG_CNT_ICNTB

case L0_FRCNTB: case L1_FRCNTB:
           reg name is :   L_REG_CNT_FRCCNTB

Thanks.
>
>> Reported-by: Euler Robot <euler.robot@huawei.com>
>> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
>> ---
>> Cc: Igor Mitsyanko <i.mitsyanko@gmail.com>
>> Cc: Peter Maydell <peter.maydell@linaro.org>
>> ---
>>  hw/timer/exynos4210_mct.c | 4 ----
>>  1 file changed, 4 deletions(-)
>>
>> diff --git a/hw/timer/exynos4210_mct.c b/hw/timer/exynos4210_mct.c
>> index 944120aea5..570cf7075b 100644
>> --- a/hw/timer/exynos4210_mct.c
>> +++ b/hw/timer/exynos4210_mct.c
>> @@ -1367,7 +1367,6 @@ static void exynos4210_mct_write(void *opaque,
>> hwaddr offset,
>>
>>      case L0_TCNTB: case L1_TCNTB:
>>          lt_i = GET_L_TIMER_IDX(offset);
>> -        index = GET_L_TIMER_CNT_REG_IDX(offset, lt_i);
>>
>>          /*
>>           * TCNTB is updated to internal register only after CNT expired.
>> @@ -1396,7 +1395,6 @@ static void exynos4210_mct_write(void *opaque,
>> hwaddr offset,
>>
>>      case L0_ICNTB: case L1_ICNTB:
>>          lt_i = GET_L_TIMER_IDX(offset);
>> -        index = GET_L_TIMER_CNT_REG_IDX(offset, lt_i);
>>
>>          s->l_timer[lt_i].reg.wstat |= L_WSTAT_ICNTB_WRITE;
>>          s->l_timer[lt_i].reg.cnt[L_REG_CNT_ICNTB] = value & @@
>> -1438,8 +1436,6 @@ static void exynos4210_mct_write(void *opaque,
>> hwaddr offset,
>>
>>      case L0_FRCNTB: case L1_FRCNTB:
>>          lt_i = GET_L_TIMER_IDX(offset);
>> -        index = GET_L_TIMER_CNT_REG_IDX(offset, lt_i);
>> -
>>          DPRINTF("local timer[%d] FRCNTB write %llx\n", lt_i, value);
>>
>>          s->l_timer[lt_i].reg.wstat |= L_WSTAT_FRCCNTB_WRITE;
>>