RE: [EXT] [PATCH v2 3/3] mtd: rawnand: micron: Address the shallow erase issue

["Bean Huo (beanhuo)" <beanhuo@xxxxxxxxxx>]

Hi, Miquel
I have two questions about your patch, please help me. 

> +	 */
> +	for (eb = first_eb; eb < first_eb + nb_eb; eb++) {
> +		/* Il all the first pages are not written yet, do it */
> +		if (micron->writtenp[eb] != MICRON_PAGE_MASK_TRIGGER)
> +			micron_nand_avoid_shallow_erase(chip, eb);
> +
> +		micron->writtenp[eb] = 0;
> +	}


Here, if the power loss happens before erasing this block, for the next time boot up,
What will happen from FS layer in case FS detect this filled data?

> +
> +	return nand_erase_nand(chip, instr, allowbbt); 
>+ }

 static int
> +micron_nand_write_oob(struct nand_chip *chip, loff_t to,
> +				 struct mtd_oob_ops *ops)
> +{
> +	struct micron_nand *micron = nand_get_manufacturer_data(chip);
> +	unsigned int eb_sz = nanddev_eraseblock_size(&chip->base);
> +	unsigned int p_sz = nanddev_page_size(&chip->base);
> +	unsigned int ppeb = nanddev_pages_per_eraseblock(&chip->base);
> +	unsigned int nb_p_tot = ops->len / p_sz;
> +	unsigned int first_eb = DIV_ROUND_DOWN_ULL(to, eb_sz);
> +	unsigned int first_p = DIV_ROUND_UP_ULL(to - (first_eb * eb_sz), p_sz);
> +	unsigned int nb_eb = DIV_ROUND_UP_ULL(first_p + nb_p_tot, ppeb);
> +	unsigned int remaining_p, eb, nb_p;
> +	int ret;
> +
> +	ret = nand_write_oob_nand(chip, to, ops);
> +	if (ret || (ops->len != ops->retlen))
> +		return ret;
> +
> +	/* Mark the last pages of the first erase block to write */
> +	nb_p = min(nb_p_tot, ppeb - first_p);
> +	micron->writtenp[first_eb] |= GENMASK(first_p + nb_p, first_p) &
> +				      MICRON_PAGE_MASK_TRIGGER;
> +	remaining_p = nb_p_tot - nb_p;
> +
> +	/* Mark all the pages of all "in-the-middle" erase blocks */
> +	for (eb = first_eb + 1; eb < first_eb + nb_eb - 1; eb++) {
> +		micron->writtenp[eb] |= MICRON_PAGE_MASK_TRIGGER;
> +		remaining_p -= ppeb;
> +	}
> +
> +	/* Mark the first pages of the last erase block to write */
> +	if (remaining_p)
> +		micron->writtenp[eb] |= GENMASK(remaining_p - 1, 0) &
> +					MICRON_PAGE_MASK_TRIGGER;
> +


This micron->written is stored in the system memory, once power cut,  for the next time
Boot up, will it be reinstated or it will be 0x00?



> +	return 0;
> +}
> +


Thanks,

Bean
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