lkml.org 
[lkml]   [2015]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH v2 1/2] mmc: dw_mmc: fix bug that cause 'Timeout sending command'
    Hi Addy,

    On Mon, Feb 9, 2015 at 12:55 PM, Addy Ke <addy.ke@rock-chips.com> wrote:
    > Because of some uncertain factors, such as worse card or worse hardware,
    > DAT[3:0](the data lines) may be pulled down by card, and mmc controller
    > will be in busy state. This should not happend when mmc controller
    > send command to update card clocks. If this happends, mci_send_cmd will
    > be failed and we will get 'Timeout sending command', and then system will
    > be blocked. To avoid this, we need reset mmc controller.
    >
    > Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
    > ---
    > drivers/mmc/host/dw_mmc.c | 28 ++++++++++++++++++++++++++++
    > 1 file changed, 28 insertions(+)
    >
    > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
    > index 4d2e3c2..b0b57e3 100644
    > --- a/drivers/mmc/host/dw_mmc.c
    > +++ b/drivers/mmc/host/dw_mmc.c
    > @@ -100,6 +100,7 @@ struct idmac_desc {
    > };
    > #endif /* CONFIG_MMC_DW_IDMAC */
    >
    > +static int dw_mci_card_busy(struct mmc_host *mmc);
    > static bool dw_mci_reset(struct dw_mci *host);
    > static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset);
    >
    > @@ -888,6 +889,31 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg)
    > cmd, arg, cmd_status);
    > }
    >
    > +static void dw_mci_wait_busy(struct dw_mci_slot *slot)
    > +{
    > + struct dw_mci *host = slot->host;
    > + unsigned long timeout = jiffies + msecs_to_jiffies(500);
    > +
    Why 500 msec?

    > + do {
    > + if (!dw_mci_card_busy(slot->mmc))
    > + return;
    > + cpu_relax();
    > + } while (time_before(jiffies, timeout));
    > +
    > + dev_err(host->dev, "Data busy (status %#x)\n",
    > + mci_readl(slot->host, STATUS));
    > +
    > + /*
    > + * Data busy, this should not happend when mmc controller send command
    > + * to update card clocks in non-volt-switch state. If it happends, we
    > + * should reset controller to avoid getting "Timeout sending command".
    > + */
    > + dw_mci_ctrl_reset(host, SDMMC_CTRL_ALL_RESET_FLAGS);
    > +
    Why you need to reset all blocks? may be CTRL_RESET is good enough here.

    > + /* Fail to reset controller or still data busy, WARN_ON! */
    > + WARN_ON(dw_mci_card_busy(slot->mmc));
    > +}
    > +
    > static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
    > {
    > struct dw_mci *host = slot->host;
    > @@ -899,6 +925,8 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
    > /* We must continue to set bit 28 in CMD until the change is complete */
    > if (host->state == STATE_WAITING_CMD11_DONE)
    > sdmmc_cmd_bits |= SDMMC_CMD_VOLT_SWITCH;
    > + else
    > + dw_mci_wait_busy(slot);
    >
    hmm...I would suggest you to call dw_mci_wait_busy() from inside
    mci_send_cmd(), seems like dw_mmc hangs while sending update clock cmd
    in multiple cases.see [1]

    [1]: http://permalink.gmane.org/gmane.linux.kernel.mmc/31140

    > if (!clock) {
    > mci_writel(host, CLKENA, 0);
    > --
    > 1.8.3.2
    >
    >
    >
    > _______________________________________________
    > linux-arm-kernel mailing list
    > linux-arm-kernel@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel



    --
    Regards,
    Alim


    \
     
     \ /
      Last update: 2015-02-10 16:41    [W:4.564 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site