From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seungwon Jeon Subject: RE: [PATCH 2/5] mmc: dw-mmc: ensure that the card is not busy when changing clock. Date: Mon, 27 Aug 2012 10:38:35 +0900 Message-ID: <000b01cd83f4$acda02c0$068e0840$%jun@samsung.com> References: <503614A5.5090906@samsung.com> <00ac01cd81ac$3eef2370$bccd6a50$%jun@samsung.com> <503708A2.9030500@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=Windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout3.samsung.com ([203.254.224.33]:44542 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750831Ab2H0Bii (ORCPT ); Sun, 26 Aug 2012 21:38:38 -0400 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0M9E004UW4K6QIG0@mailout3.samsung.com> for linux-mmc@vger.kernel.org; Mon, 27 Aug 2012 10:38:36 +0900 (KST) Received: from DOTGIHJUN01 ([12.23.118.161]) by mmp2.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0M9E00BFE4KBXS30@mmp2.samsung.com> for linux-mmc@vger.kernel.org; Mon, 27 Aug 2012 10:38:36 +0900 (KST) In-reply-to: <503708A2.9030500@samsung.com> Content-language: ko Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: 'Jaehoon Chung' Cc: 'linux-mmc' , 'Chris Ball' , 'Kyungmin Park' , 'Will Newton' , 'James Hogan' On Friday, August 24, 2012, Jaehoon Chung wrote: > 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 If you know a point in time, we can reproduce it. > > 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 > > > > -- > 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