Re: [PATCH v7 1/6] riscv: mm: dma-noncoherent: Switch using function pointers for cache management

Lad, Prabhakar
2023-04-06T19:00:00Z

Hi Christoph,

On Tue, Apr 4, 2023 at 6:29 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Thu, Mar 30, 2023 at 09:42:12PM +0100, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> >
> > Currently, selecting which CMOs to use on a given platform is done using
> > and ALTERNATIVE_X() macro. This was manageable when there were just two
> > CMO implementations, but now that there are more and more platforms coming
> > needing custom CMOs, the use of the ALTERNATIVE_X() macro is unmanageable.
> >
> > To avoid such issues this patch switches to use of function pointers
> > instead of ALTERNATIVE_X() macro for cache management (the only drawback
> > being performance over the previous approach).
> >
> > void (*clean_range)(unsigned long addr, unsigned long size);
> > void (*inv_range)(unsigned long addr, unsigned long size);
> > void (*flush_range)(unsigned long addr, unsigned long size);
> >
>
> NAK. Function pointers for somthing high performance as cache
> maintainance is a complete no-go.
>
Ok, I will take the ALTERNATIVE() macro route.

Cheers,
Prabhakar