On Sun, Oct 16, 2022, at 5:48 PM, Tony Huang wrote:
> This is a patch for mmc driver for Sunplus SP7021 SOC.
> Supports eMMC 4.41 DDR 104MB/s speed mode.
>
> Signed-off-by: Tony Huang <tonyhuang.sunplus@xxxxxxxxx>
Looks ok to me me overall.
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Just one more thing I noticed:
> +#define SPMMC_TIMEOUT 500000
...
> +static inline int spmmc_wait_finish(struct spmmc_host *host)
> +{
> + u32 state;
> +
> + return readl_poll_timeout_atomic(host->base + SPMMC_SD_STATE_REG,
> state,
> + (state & SPMMC_SDSTATE_FINISH), 1, SPMMC_TIMEOUT);
> +}
> +
> +static inline int spmmc_wait_sdstatus(struct spmmc_host *host,
> unsigned int status_bit)
> +{
> + u32 status;
> +
> + return readl_poll_timeout_atomic(host->base + SPMMC_SD_STATUS_REG,
> status,
> + (status & status_bit), 1, SPMMC_TIMEOUT);
> +}
500ms seems like an awfully long time for a busy-wait, I wonder if this
could be improved in some way. Is this always called from atomic context?
If not, any callers from non-atomic context could use
readl_poll_timeout() instead, or maybe there could be a shorter
timeout in atomic context, with a fallback to a non-atomic
workqueue if that times out, so only the MMC access will stall but
not the entire system.
The same problem does appear to be in dw_mmc.c and mtk-sd.c but not
in sdhci*.c, so I don't know if this is avoidable.
Arnd
