From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH 2/5] mmc: dw-mmc: ensure that the card is not busy when changing clock. Date: Fri, 24 Aug 2012 13:52:50 +0900 Message-ID: <503708A2.9030500@samsung.com> References: <503614A5.5090906@samsung.com> <00ac01cd81ac$3eef2370$bccd6a50$%jun@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout4.samsung.com ([203.254.224.34]:20335 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750847Ab2HXExL (ORCPT ); Fri, 24 Aug 2012 00:53:11 -0400 Received: from epcpsbgm1.samsung.com (mailout4.samsung.com [203.254.224.34]) by mailout4.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0M98005A1THUU3K0@mailout4.samsung.com> for linux-mmc@vger.kernel.org; Fri, 24 Aug 2012 13:53:08 +0900 (KST) Received: from [10.90.51.55] by mmp1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0M9800F53TKJ6Y10@mmp1.samsung.com> for linux-mmc@vger.kernel.org; Fri, 24 Aug 2012 13:53:08 +0900 (KST) In-reply-to: <00ac01cd81ac$3eef2370$bccd6a50$%jun@samsung.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Seungwon Jeon Cc: 'Jaehoon Chung' , 'linux-mmc' , 'Chris Ball' , 'Kyungmin Park' , 'Will Newton' , 'James Hogan' Hi Seungwon, On 08/24/2012 12:55 PM, Seungwon Jeon wrote: > Hi Jaehoon, > > On Thursday, August 23, 2012, Jaehoon Chung wrote: >> To avoid glitches in the card clock output, >> need to check whether card is busy or not. > Could you describe the problem more? synopsys spec is mentioned. (7.1 Software/Hardware Restrictions) "Before disabling clock, ensure that card is not busy due to any previous data command." > In which situation did you meet this? At specific board, i found the problem that didn't inform ciu. (It didn't produce always.) At that time, i checked the status register whether card is busy or not. (Start bit of CMD register is cleared, but card is busy.) Current code didn't check the card status. Just check whether the start-bit cleared. host regard that command is completed, will send the next command. But next command didn't issue because Card is busy. This patch can prevent this situation. If you have any comment or opinion, please let me know. it's great help to me Best Regards, Jaehoon Chung > > Thanks, > Seungwon Jeon >> >> Signed-off-by: Jaehoon Chung >> Signed-off-by: Kyungmin Park >> --- >> drivers/mmc/host/dw_mmc.c | 30 ++++++++++++++++++++++++------ >> drivers/mmc/host/dw_mmc.h | 1 + >> 2 files changed, 25 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 36f98c0..8bef3c2 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -623,6 +623,27 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg) >> cmd, arg, cmd_status); >> } >> >> +static void dw_mci_inform_ciu(struct dw_mci_slot *slot) >> +{ >> + struct dw_mci *host = slot->host; >> + unsigned long timeout = jiffies + msecs_to_jiffies(500); >> + u32 ctrl, status; >> + >> + do { >> + status = mci_readl(host, STATUS); >> + if (!(status & SDMMC_DATA_BUSY)) >> + break; >> + ctrl = mci_readl(host, CTRL); >> + ctrl |= SDMMC_CTRL_RESET; >> + mci_writel(host, CTRL, ctrl); >> + } while (time_before(jiffies, timeout)); >> + >> + if (status & SDMMC_DATA_BUSY) >> + dev_err(&slot->mmc->class_dev,"Card is busy..!\n"); >> + >> + mci_send_cmd(slot, SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); >> +} >> + >> static void dw_mci_setup_bus(struct dw_mci_slot *slot) >> { >> struct dw_mci *host = slot->host; >> @@ -650,15 +671,13 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot) >> mci_writel(host, CLKSRC, 0); >> >> /* inform CIU */ >> - mci_send_cmd(slot, >> - SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); >> + dw_mci_inform_ciu(slot); >> >> /* set clock to desired speed */ >> mci_writel(host, CLKDIV, div); >> >> /* inform CIU */ >> - mci_send_cmd(slot, >> - SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); >> + dw_mci_inform_ciu(slot); >> >> /* enable clock; only low power if no SDIO */ >> clk_en_a = SDMMC_CLKEN_ENABLE << slot->id; >> @@ -667,8 +686,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot) >> mci_writel(host, CLKENA, clk_en_a); >> >> /* inform CIU */ >> - mci_send_cmd(slot, >> - SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); >> + dw_mci_inform_ciu(slot); >> >> host->current_speed = slot->clock; >> } >> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h >> index 15c27e1..b6a1a78 100644 >> --- a/drivers/mmc/host/dw_mmc.h >> +++ b/drivers/mmc/host/dw_mmc.h >> @@ -127,6 +127,7 @@ >> #define SDMMC_CMD_INDX(n) ((n) & 0x1F) >> /* Status register defines */ >> #define SDMMC_GET_FCNT(x) (((x)>>17) & 0x1FFF) >> +#define SDMMC_DATA_BUSY BIT(9) >> /* Internal DMAC interrupt defines */ >> #define SDMMC_IDMAC_INT_AI BIT(9) >> #define SDMMC_IDMAC_INT_NI BIT(8) >> -- >> 1.7.4.1 >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >