Re: [PATCH v4 1/3] mmc: dw_mmc: update clock after host reach a stable voltage

Alim Akhtar
2015-02-15T23:29:29Z

Hi Addy,

On Sat, Feb 14, 2015 at 11:47 AM, Addy Ke <addy.ke@rock-chips.com> wrote:
> As show in mmc_power_up(), in MMC_POWER_UP state, the voltage isn't
> stable and we may get 'data busy' which can't be cleaned by resetting
> all blocks. So we should not send command to update clock in this state.
>
> Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
> ---
> drivers/mmc/host/dw_mmc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 4d2e3c2..3472f9b 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1102,7 +1102,8 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> drv_data->set_ios(slot->host, ios);
>
> /* Slot specific timing and width adjustment */
> - dw_mci_setup_bus(slot, false);
> + if (ios->power_mode != MMC_POWER_UP)
> + dw_mci_setup_bus(slot, false);
>
This looks a HACK to me.
If stabilizing host voltage regulator is the problem, can you try out
below patch, and see if this resolve your issue?

===========
[PATCH] mmc: dw_mmc: Wait for host voltage regulator to be stable

Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
---
drivers/mmc/host/dw_mmc.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 4d2e3c2..dc10fbb 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1202,6 +1202,9 @@ static int dw_mci_switch_voltage(struct mmc_host
*mmc, struct mmc_ios *ios)
}
mci_writel(host, UHS_REG, uhs);

+ /* wait for 5ms so that host voltage regulator is stable */
+ usleep_range(5000, 5500);
+
return 0;
}

===============

> if (slot->host->state == STATE_WAITING_CMD11_DONE && ios->clock != 0)
> slot->host->state = STATE_IDLE;
> --
> 1.8.3.2
>
>

--
Regards,
Alim