[U-Boot] [PATCH v1 1/6] serial: stm32x7: cleanup code

[Patrice CHOTARD]

Hi Bo

On 09/29/2017 08:12 AM, Bo Shen wrote:
> Hi Patrice,
> 
> On 09/27/2017 06:44 AM, patrice.chotard at st.com wrote:
>> From: Patrice Chotard <patrice.chotard at st.com>
>>
>> Use BIT() macro and GENMASK() macro
>>
>> Signed-off-by: Patrice Chotard <patrice.chotard at st.com>
>> Reviewed-by: Vikas Manocha <vikas.manocha at st.com>
>> ---
>>   drivers/serial/serial_stm32x7.h | 18 +++++++++---------
>>   1 file changed, 9 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/serial/serial_stm32x7.h 
>> b/drivers/serial/serial_stm32x7.h
>> index 9fe37af..6d36b74 100644
>> --- a/drivers/serial/serial_stm32x7.h
>> +++ b/drivers/serial/serial_stm32x7.h
>> @@ -28,18 +28,18 @@ struct stm32x7_serial_platdata {
>>       unsigned long int clock_rate;
>>   };
>> -#define USART_CR1_OVER8            (1 << 15)
>> -#define USART_CR1_TE            (1 << 3)
>> -#define USART_CR1_RE            (1 << 2)
>> -#define USART_CR1_UE            (1 << 0)
>> +#define USART_CR1_OVER8            BIT(15)
>> +#define USART_CR1_TE            BIT(3)
>> +#define USART_CR1_RE            BIT(2)
>> +#define USART_CR1_UE            BIT(0)
>> -#define USART_CR3_OVRDIS        (1 << 12)
>> +#define USART_CR3_OVRDIS        BIT(12)
>> -#define USART_SR_FLAG_RXNE        (1 << 5)
>> -#define USART_SR_FLAG_TXE        (1 << 7)
>> +#define USART_SR_FLAG_RXNE        BIT(5)
>> +#define USART_SR_FLAG_TXE        BIT(7)
>> -#define USART_BRR_F_MASK        0xFF
>> +#define USART_BRR_F_MASK        GENMASK(7, 0)
>>   #define USART_BRR_M_SHIFT        4
>> -#define USART_BRR_M_MASK        0xFFF0
>> +#define USART_BRR_M_MASK        GENMASK(15, 4)
> 
> In stm32f7, according to the datasheet, there is no fraction and 
> mantissa. Would you please confirm that?

Agree,
"mantissa" is a different wording for BRR[15:4] bits
and "fraction" is used for BRR[0:3] bits


> 
> At the same time, it makes me thinking the BRR is calculated differently 
> between stm32f7 and stm32f4, would you please check it also in the 
> driver code?

Previously BRR was calculated with a more complex formula, i simply 
reused the same BRR formula from the kernel serial driver common to 
F4/F7/H7 (see drivers/tty/serial/stm32-usart.c)


> 
>>   #endif
>>
> 
> Best Regards,
> Bo Shen

Regards

Patrice