On 30/07/20 2:41 am, Faiz Abbas wrote:
> There is a one time delay because of a card detect debounce timer in the
> controller IP. This timer runs as soon as power is applied to the module
> regardless of whether a card is present or not and any writes to
> SDHCI_POWER_ON will return 0 before it expires. This timeout has been
> measured to be about 1 second in am654x and j721e.
>
> Write-and-read-back in a loop on SDHCI_POWER_ON for a maximum of
> 1.5 seconds to make sure that the controller actually powers on.
>
> Signed-off-by: Faiz Abbas <faiz_abbas@xxxxxx>
> ---
> drivers/mmc/host/sdhci_am654.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index 1718b9e8af63..55cff9de2f3e 100644
> --- a/drivers/mmc/host/sdhci_am654.c
> +++ b/drivers/mmc/host/sdhci_am654.c
> @@ -272,6 +272,7 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
> sdhci_set_clock(host, clock);
> }
>
> +#define MAX_POWER_ON_TIMEOUT 1500 /* ms */
> static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
> {
> unsigned char timing = host->mmc->ios.timing;
> @@ -291,6 +292,26 @@ static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
> }
>
> writeb(val, host->ioaddr + reg);
> + if (reg == SDHCI_POWER_CONTROL && (val & SDHCI_POWER_ON)) {
> + /*
> + * Power on will not happen until the card detect debounce
> + * timer expires. Wait at least 1.5 seconds for the power on
> + * bit to be set
> + */
Can you use readb_poll_timeout() here?
> + ktime_t timeout = ktime_add_ms(ktime_get(),
> + MAX_POWER_ON_TIMEOUT);
> + do {
> + if (ktime_compare(ktime_get(), timeout) > 0) {
> + dev_warn(mmc_dev(host->mmc),
> + "Power on failed\n");
> +
> + return;
> + }
> +
> + writeb(val, host->ioaddr + reg);
> + usleep_range(1000, 10000);
> + } while (!(readb(host->ioaddr + reg) & SDHCI_POWER_ON));
> + }
> }
>
> static int sdhci_am654_execute_tuning(struct mmc_host *mmc, u32 opcode)
>
