Re: [PATCH 04/18] mmc: meson-gx: improve meson_mmc_start_cmd

[Kevin Hilman <khilman@baylibre.com>]

Heiner Kallweit <hkallweit1@gmail.com> writes:

> Remove use of unneeded members cmd_arg and cmd_resp.
> Setting SD_EMMC_CMD_RSP is only needed if CMD_CFG_RESP_NUM is set,
> so don't write this register in all other cases.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

I'm not sure I like this change.  This works now because there is only
one descriptor used, but one of the next things to work on in this
driver is taking advantage of the internal DMA capabilities, which means
having a chain of descriptorsall filled out in memory.

Kevin

> ---
>  drivers/mmc/host/meson-gx-mmc.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index ece38b44..630e0590 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -456,7 +456,6 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
>  	desc->cmd_cfg |= (cmd->opcode & CMD_CFG_CMD_INDEX_MASK)	<<
>  		CMD_CFG_CMD_INDEX_SHIFT;
>  	desc->cmd_cfg |= CMD_CFG_OWNER;  /* owned by CPU */
> -	desc->cmd_arg = cmd->arg;
>  
>  	/* Response */
>  	if (cmd->flags & MMC_RSP_PRESENT) {
> @@ -464,7 +463,7 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
>  		if (cmd->flags & MMC_RSP_136)
>  			desc->cmd_cfg |= CMD_CFG_RESP_128;
>  		desc->cmd_cfg |= CMD_CFG_RESP_NUM;
> -		desc->cmd_resp = 0;
> +		writel(0, host->regs + SD_EMMC_CMD_RSP);
>  
>  		if (!(cmd->flags & MMC_RSP_CRC))
>  			desc->cmd_cfg |= CMD_CFG_RESP_NOCRC;
> @@ -540,9 +539,8 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
>  	desc->cmd_cfg |= CMD_CFG_END_OF_CHAIN;
>  	writel(desc->cmd_cfg, host->regs + SD_EMMC_CMD_CFG);
>  	writel(desc->cmd_data, host->regs + SD_EMMC_CMD_DAT);
> -	writel(desc->cmd_resp, host->regs + SD_EMMC_CMD_RSP);
>  	wmb(); /* ensure descriptor is written before kicked */
> -	writel(desc->cmd_arg, host->regs + SD_EMMC_CMD_ARG);
> +	writel(cmd->arg, host->regs + SD_EMMC_CMD_ARG);
>  }
>  
>  static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)