Re: [PATCH v4 2/3] virtio-spi: Add virtio-spi.h

On 8/21/2025 4:45 PM, Michael S. Tsirkin wrote:


>> +
>> +/* Sample data on trailing clock edge */
>> +#define VIRTIO_SPI_CPHA			_BITUL(0)
>> +/* Clock is high when IDLE */
>> +#define VIRTIO_SPI_CPOL			_BITUL(1)
>> +/* Chip Select is active high */
>> +#define VIRTIO_SPI_CS_HIGH			_BITUL(2)
>> +/* Transmit LSB first */
>> +#define VIRTIO_SPI_MODE_LSB_FIRST		_BITUL(3)
>> +/* Loopback mode */
>> +#define VIRTIO_SPI_MODE_LOOP			_BITUL(4)
> 
> It is generally preferable to have an enum with just bit
> numbers.
> 
> 
> E.g.
> 
> enum {
> VIRTIO_SPI_F_CPHA = 0,
> }
> 
> 
> Userspace can add _BITUL wrappers itself if it
> wants.
> 
> 

Hi Michael,

Thank you for the suggestion regarding the bit definitions.

Would it be acceptable to keep the current macro definitions with 
_BITUL() because these macros are also used within the virtio SPI driver 
itself?

Looking forward to your guidance.

Best regards,
Haixu Cui