Re: [PATCH v2] scsi: libsas: Allocation SMP request is aligned to ARCH_DMA_MINALIGN

[Christoph Hellwig]

On Tue, Mar 26, 2024 at 01:32:09PM +0000, John Garry wrote:
> > > +	u8 *p;
> > > +
> > > +	size = ALIGN(size, ARCH_DMA_MINALIGN);
> 
> 
> If this is a hisi_sas requirement, then why use ARCH_DMA_MINALIGN and not
> 16B as minimum alignment?
> 
> Or are we really talking about an arch requirement?

One thing is that we should never allocate unaligned memory for
anything DMA mapped, or data will be corrupted by non-coherent DMA.
So ARCH_DMA_MINALIGN needs to be here.  If specific hardware has
further requirements we'll need to communicated it through a field
or op vector.