Re: [PATCH v7 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller

[Liang Yang]

On 2018/12/10 19:38, Boris Brezillon wrote:
> On Mon, 10 Dec 2018 19:23:46 +0800
> Liang Yang <liang.yang@xxxxxxxxxxx> wrote:
>
> > > > +			mtd->ecc_stats.failed++;
> > > > +			continue;
> > > > +		}
> > > > +		mtd->ecc_stats.corrected += ECC_ERR_CNT(*info);
> > > > +		bitflips = max_t(u32, bitflips, ECC_ERR_CNT(*info));
> > > > +	}
> > >
> > > Are you sure you handle correctly empty pages with bf?
> > >    
> > if scramble is enable, i would say yes here.
> > when scramble is disabled, i am considering how to use the helper
> > nand_check_erased_ecc_chunk, but it seems that i can't get the ecc
> > bytes which is caculated by ecc engine.by the way, nfc dma doesn't send
> > out the ecc parity bytes.
>
> Even if the ECC engine is disabled?
No.
When ECC engine is disabled, it can read the ecc parity bytes ; but 
there is another problem that i need to consider how code struct looks 
better when reading error with ecc opened and then try to raw read.
Is there a good idea?

> > so i would suggest using scramble.
>
> No, please don't force people to use the scrambler.
>
> > > > +
> > > > +const void *
> > > > +meson_nand_op_get_dma_safe_output_buf(const struct nand_op_instr *instr)
> > > > +{
> > > > +	if (WARN_ON(instr->type != NAND_OP_DATA_OUT_INSTR))
> > > > +		return NULL;
> > > > +
> > > > +	if (virt_addr_valid(instr->ctx.data.buf.out) &&
> > > > +	    !object_is_on_stack(instr->ctx.data.buf.out))
> > >
> > > Can you please create helpers for that? I guess it will help removing
> > > these checks once the core will have a DMA-safe approach.
> > >    
> > I will use below definition:
> > #define BUFFER_IS_DMA_SAFE(x)	\
> > 	(virt_addr_valid((x)) && (!object_is_on_stack((x))))
> >
> > Is it ok?
>
> Please define a function, not a macro.
> ok
> .