Re: [PATCH 1/2] mmc: add helper to query max enhanced part size

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi,

On 9/22/21 9:30 PM, Matthias Schiffer wrote:
> From: Markus Niebel <Markus.Niebel@ew.tq-group.com>
> 
> This helper will be used later on in an extension of the mmc
> command.
> 
> Signed-off-by: Markus Niebel <Markus.Niebel@ew.tq-group.com>
> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> ---
>  drivers/mmc/mmc.c | 38 ++++++++++++++++++++++++++++++++++++++
>  include/mmc.h     |  1 +
>  2 files changed, 39 insertions(+)
> 
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> index d3babbfeb1c..c1b1ef7eb0b 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -1039,6 +1039,44 @@ int mmc_switch_part(struct mmc *mmc, unsigned int part_num)
>  }
>  
>  #if CONFIG_IS_ENABLED(MMC_HW_PARTITIONING)
> +int mmc_max_enhanced_size_sectors(struct mmc *mmc, u64 *size)
> +{
> +	u64 sz;
> +	int err;
> +
> +	ALLOC_CACHE_ALIGN_BUFFER(u8, ext_csd, MMC_MAX_BLOCK_LEN);
> +
> +	if (IS_SD(mmc) || mmc->version < MMC_VERSION_4_41) {
> +		pr_err("eMMC >= 4.4 required for enhanced user data area\n");

Error log is considering about only eMMC. It can be SD-card.

> +		return -EMEDIUMTYPE;
> +	}
> +
> +	if (!(mmc->part_support & PART_SUPPORT)) {
> +		pr_err("Card does not support partitioning\n");
> +		return -EMEDIUMTYPE;
> +	}
> +
> +	if (!mmc->hc_wp_grp_size) {
> +		pr_err("Card does not define HC WP group size\n");
> +		return -EMEDIUMTYPE;
> +	}
> +
> +	err = mmc_send_ext_csd(mmc, ext_csd);
> +	if (err)
> +		return err;
> +
> +	sz =
> +		(ext_csd[EXT_CSD_MAX_ENH_SIZE_MULT + 2] << 16) +
> +		(ext_csd[EXT_CSD_MAX_ENH_SIZE_MULT + 1] << 8) +
> +		ext_csd[EXT_CSD_MAX_ENH_SIZE_MULT];
> +	sz *= ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE];
> +	sz *= ext_csd[EXT_CSD_HC_WP_GRP_SIZE];
> +	sz *= SZ_1K;

To use the num of sector, i think better that is adding Comment.
And using not "sz" as variable. It seems to describe real size, not sector.
According to spec, it's 512kByte. It can be confused.

Best Regards,
Jaehoon Chung

> +	*size = sz;
> +
> +	return 0;
> +}
> +
>  int mmc_hwpart_config(struct mmc *mmc,
>  		      const struct mmc_hwpart_conf *conf,
>  		      enum mmc_hwpart_conf_mode mode)
> diff --git a/include/mmc.h b/include/mmc.h
> index b92e2553402..3e1fc82d9b4 100644
> --- a/include/mmc.h
> +++ b/include/mmc.h
> @@ -846,6 +846,7 @@ void print_mmc_devices(char separator);
>   */
>  int get_mmc_num(void);
>  int mmc_switch_part(struct mmc *mmc, unsigned int part_num);
> +int mmc_max_enhanced_size_sectors(struct mmc *mmc, u64 *size);
>  int mmc_hwpart_config(struct mmc *mmc, const struct mmc_hwpart_conf *conf,
>  		      enum mmc_hwpart_conf_mode mode);
>  
>