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SubjectRe: [RFC PATCH V4 4/6] RISC-V: Implement arch_sync_dma* functions
On Wed, Sep 15, 2021 at 3:50 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Sat, Sep 11, 2021 at 05:21:37PM +0800, guoren@kernel.org wrote:
> > +static void __dma_sync(phys_addr_t paddr, size_t size, enum dma_data_direction dir)
> > +{
> > + if ((dir == DMA_FROM_DEVICE) && (dma_cache_sync->cache_invalidate))
> > + dma_cache_sync->cache_invalidate(paddr, size);
> > + else if ((dir == DMA_TO_DEVICE) && (dma_cache_sync->cache_clean))
> > + dma_cache_sync->cache_clean(paddr, size);
> > + else if ((dir == DMA_BIDIRECTIONAL) && dma_cache_sync->cache_flush)
> > + dma_cache_sync->cache_flush(paddr, size);
> > +}
>
> Despite various snipplets this is a still pretty much the broken previous
> versions. These need to use the CMO instructions directly which are
> about to go into review, and then your SBI can trap on those can call
> whatever non-standard mess you're using.
I think you mean put an ALTERNATIVE slot in the prologue of __dma_sync?

#define ALT_DMA_SYNC() \
asm(ALTERNATIVE(".rept 64\n nop\n .endr\n", "<vendor code>",
XXX_VENDOR_ID, \
ERRATA_XXX, CONFIG_ERRATA_XXX) \
: : : "memory")

static void __dma_sync(phys_addr_t paddr, size_t size, enum
dma_data_direction dir)
{
ALT_DMA_SYNC();

/* future cmo codes */
}




--
Best Regards
Guo Ren

ML: https://lore.kernel.org/linux-csky/

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