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

From: Alim Akhtar <alim.akhtar@gmail.com>
To: Addy Ke <addy.ke@rock-chips.com>
Cc: "Jaehoon Chung" <jh80.chung@samsung.com>,
	"Ulf Hansson" <ulf.hansson@linaro.org>,
	"Olof Johansson" <olof@lixom.net>,
	"Andrzej Hajda" <a.hajda@samsung.com>,
	"Douglas Anderson" <dianders@chromium.org>,
	"Heiko Stübner" <heiko@sntech.de>,
	"Eddie Cai" <cf@rock-chips.com>,
	lintao@rock-chips.com, "Tao Huang" <huangtao@rock-chips.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v4 1/3] mmc: dw_mmc: update clock after host reach a stable voltage
Date: Mon, 16 Feb 2015 04:58:47 +0530	[thread overview]
Message-ID: <CAGOxZ53ndi_hYDGBGhY-7q8aOrFid1=D=_5KEbUvzTsnybJQ3Q@mail.gmail.com> (raw)
In-Reply-To: <1423894668-8886-2-git-send-email-addy.ke@rock-chips.com>

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
