Re: [PATCH v6 7/9] mmc: core: Adjust ACMD22 to SDUC

[Adrian Hunter <adrian.hunter@intel.com>]

On 4/09/24 17:52, Avri Altman wrote:
> ACMD22 is used to verify the previously write operation.  Normally, it
> returns the number of written sectors as u32.  SDUC, however, returns it
> as u64.  This is not a superfluous requirement, because SDUC writes may
> exceeds 2TB.  For Linux mmc however, the previously write operation
> could not be more than the block layer limits, thus we make room for a
> u64 and cast the returning value to u32.
> 
> Signed-off-by: Avri Altman <avri.altman@wdc.com>
> ---
>  drivers/mmc/core/block.c | 29 +++++++++++++++++++++++------
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 50d37c4f5a50..f36611512a1d 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -50,6 +50,7 @@
>  #include <linux/mmc/sd.h>
>  
>  #include <linux/uaccess.h>
> +#include <asm/unaligned.h>
>  
>  #include "queue.h"
>  #include "block.h"
> @@ -994,11 +995,10 @@ static int mmc_sd_num_wr_blocks(struct mmc_card *card, u32 *written_blocks)
>  	int err;
>  	u32 result;
>  	__be32 *blocks;
> -
> +	u8 resp_sz;

Could do the initialization here i.e.

	u8 resp_sz = mmc_card_ult_capacity(card) ? 8 : 4;

>  	struct mmc_request mrq = {};
>  	struct mmc_command cmd = {};
>  	struct mmc_data data = {};
> -
>  	struct scatterlist sg;
>  
>  	err = mmc_app_cmd(card->host, card);
> @@ -1009,7 +1009,14 @@ static int mmc_sd_num_wr_blocks(struct mmc_card *card, u32 *written_blocks)
>  	cmd.arg = 0;
>  	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
>  
> -	data.blksz = 4;
> +	/*
> +	 * Normally, ACMD22 returns the number of written sectors as u32.
> +	 * SDUC, however, returns it as u64.  This is not a superfluous
> +	 * requirement, because SDUC writes may exceed 2TB.
> +	 */
> +	resp_sz = mmc_card_ult_capacity(card) ? 8 : 4;
> +
> +	data.blksz = resp_sz;
>  	data.blocks = 1;
>  	data.flags = MMC_DATA_READ;
>  	data.sg = &sg;
> @@ -1019,15 +1026,25 @@ static int mmc_sd_num_wr_blocks(struct mmc_card *card, u32 *written_blocks)
>  	mrq.cmd = &cmd;
>  	mrq.data = &data;
>  
> -	blocks = kmalloc(4, GFP_KERNEL);
> +	blocks = kmalloc(resp_sz, GFP_KERNEL);

Separate issue, but this should probably be GFP_NOIO, or
just have the buffer in mmc_host or mmc_card

>  	if (!blocks)
>  		return -ENOMEM;
>  
> -	sg_init_one(&sg, blocks, 4);
> +	sg_init_one(&sg, blocks, resp_sz);
>  
>  	mmc_wait_for_req(card->host, &mrq);
>  
> -	result = ntohl(*blocks);
> +	if (mmc_card_ult_capacity(card)) {
> +		u64 blocks_64 = get_unaligned_be64(blocks);
> +		/*
> +		 * For Linux mmc however, the previously write operation could
> +		 * not be more than the block layer limits, thus just make room
> +		 * for a u64 and cast the response back to u32.
> +		 */
> +		result = blocks_64 > UINT_MAX ? UINT_MAX : (u32)blocks_64;

Perhaps:
		result = clamp_val(get_unaligned_be64(blocks), 0, UINT_MAX);

> +	} else {
> +		result = ntohl(*blocks);
> +	}
>  	kfree(blocks);
>  
>  	if (cmd.error || data.error)