From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH v2 1/2] mmc: dw_mmc: fix bug that cause 'Timeout sending command' Date: Mon, 09 Feb 2015 19:01:04 +0900 Message-ID: <54D88560.4050808@samsung.com> References: <1423134801-23219-1-git-send-email-addy.ke@rock-chips.com> <1423466726-20833-1-git-send-email-addy.ke@rock-chips.com> <1423466726-20833-2-git-send-email-addy.ke@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <1423466726-20833-2-git-send-email-addy.ke@rock-chips.com> Sender: linux-kernel-owner@vger.kernel.org To: Addy Ke , robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, rdunlap@infradead.org, tgih.jun@samsung.com, chris@printf.net, ulf.hansson@linaro.org, dinguyen@altera.com, heiko@sntech.de, olof@lixom.net, dianders@chromium.org, sonnyrao@chromium.org, amstan@chromium.org, djkurtz@chromium.org Cc: devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, zhenfu.fang@rock-chips.com, cf@rock-chips.com, lintao@rock-chips.com, chenfen@rock-chips.com, zyf@rock-chips.com, xjq@rock-chips.com, huangtao@rock-chips.com, zyw@rock-chips.com, yzq@rock-chips.com, hj@rock-chips.com, kever.yang@rock-chips.com, zhangqing@rock-chips.com, hl@rock-chips.com List-Id: linux-mmc@vger.kernel.org Hi, Addy. On 02/09/2015 04:25 PM, Addy Ke 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 > --- > 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); > + > + 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); If reset is failed, then dw_mci_ctrl_reset should return "false". ret = dw_mci_ctrl_reset(); WARN_ON(!ret || dw_mci_card_busy(slot->mmc)); Is it right? In my experiment, if reset is failed or card is busy, eMMC can't work anymore..right? I think this patch is reasonable to prevent blocking issue. Best Regards, Jaehoon Chung > + > + /* 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); > > if (!clock) { > mci_writel(host, CLKENA, 0); >