From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH v2 1/5] mmc: dw-mmc: ensure that the card is not busy when changing clock Date: Wed, 29 Aug 2012 11:02:00 +0900 Message-ID: <503D7818.2040402@samsung.com> References: <503C797D.4040404@samsung.com> <003501cd8584$a1cd8370$e5688a50$%jun@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:23957 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751942Ab2H2CCG (ORCPT ); Tue, 28 Aug 2012 22:02:06 -0400 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout2.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0M9H00GJ9UYYM690@mailout2.samsung.com> for linux-mmc@vger.kernel.org; Wed, 29 Aug 2012 11:02:05 +0900 (KST) Received: from [10.90.51.55] by mmp1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0M9H00K2XUZGPW00@mmp1.samsung.com> for linux-mmc@vger.kernel.org; Wed, 29 Aug 2012 11:02:04 +0900 (KST) In-reply-to: <003501cd8584$a1cd8370$e5688a50$%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' , 'Thomas Abraham' On 08/29/2012 10:21 AM, Seungwon Jeon wrote: > On Tuesday, August 28, 2012, Jaehoon Chung wrote: >> synopsys spec is mentioned. (7.1 Software/Hardware Restrictions) >> "Before disabling clock, ensure that card is not busy due to any previous data command." >> >> 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. >> >> Signed-off-by: Jaehoon Chung >> --- >> drivers/mmc/host/dw_mmc.c | 27 +++++++++++++++++++++------ >> drivers/mmc/host/dw_mmc.h | 1 + >> 2 files changed, 22 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 36f98c0..e30d3ed 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -623,6 +623,24 @@ 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(10); > 10ms is from test? It's tested...it's not exactly value..but never spent the time. > >> + 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)); >> + >> + 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 +668,13 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot) > According to your quotation of manual("Before disabling clock, ...), > Place of dw_mci_inform_ciu is proper here? manual is mentioned "before the disabling clock". but i think no problem before send the command. > > dw_mci_inform_ciu(slot); > > /* disable clock */ > mci_writel(host, CLKENA, 0); > mci_writel(host, CLKSRC, 0); > >> 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); > And then, since start to change clock sequence, there is no need to check busy-status. > Just need to update clock with origin code. Right, didn't check the busy-status. but there is also no reason that didn't need to check busy-status. >> >> /* enable clock; only low power if no SDIO */ >> clk_en_a = SDMMC_CLKEN_ENABLE << slot->id; >> @@ -667,8 +683,7 @@ 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); > Same here. > > Thanks, > Seungwon Jeon >> >> 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 >