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Message-ID: <CAPDyKFosQkxaFAKo0dm0TajgXqKG7XqRM1tTqR2vTsHzVrocfQ@mail.gmail.com>
Date: Thu, 1 Dec 2016 10:51:36 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Yong Mao <yong.mao@...iatek.com>
Cc: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Matthias Brugger <matthias.bgg@...il.com>,
YH Huang <yh.huang@...iatek.com>,
Mathias Nyman <mathias.nyman@...ux.intel.com>,
Chunfeng Yun <chunfeng.yun@...iatek.com>,
Eddie Huang <eddie.huang@...iatek.com>,
Philipp Zabel <p.zabel@...gutronix.de>,
Chaotian Jing <chaotian.jing@...iatek.com>,
Nicolas Boichat <drinkcat@...omium.org>,
Douglas Anderson <dianders@...omium.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
linux-mediatek@...ts.infradead.org,
srv_heupstream <srv_heupstream@...iatek.com>
Subject: Re: [PATCH 1/4] mmc: mediatek: Fix CMD6 timeout issue
On 8 November 2016 at 07:08, Yong Mao <yong.mao@...iatek.com> wrote:
> From: yong mao <yong.mao@...iatek.com>
>
> When initializing EMMC, after switch to HS400,
> it will issue CMD6 to change ext_csd, if first CMD6 got CRC
> error, the repeat CMD6 may get timeout, that's
> because SDCBSY was cleared by msdc_reset_hw()
Sorry for the delay!
We have recently been re-working the sequence for how to deal more
properly with CMD6 in the mmc core.
The changes done so far should mostly concern switches to HS and HS
DDR, but I think you should run a re-test to make sure you still hit
the same problems.
>
> Signed-off-by: Yong Mao <yong.mao@...iatek.com>
> Signed-off-by: Chaotian Jing <chaotian.jing@...iatek.com>
> ---
> drivers/mmc/host/mtk-sd.c | 77 ++++++++++++++++++++++++++++++---------------
> 1 file changed, 51 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 84e9afc..b29683b 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -826,6 +826,15 @@ static bool msdc_cmd_done(struct msdc_host *host, int events,
> return true;
> }
>
> +static int msdc_card_busy(struct mmc_host *mmc)
> +{
> + struct msdc_host *host = mmc_priv(mmc);
> + u32 status = readl(host->base + MSDC_PS);
> +
> + /* check if data0 is low */
> + return !(status & BIT(16));
> +}
> +
> /* It is the core layer's responsibility to ensure card status
> * is correct before issue a request. but host design do below
> * checks recommended.
Hmm. Why?
I think you should rely on the mmc core to invoke the ->card_busy()
ops instead. The core knows better when it's needed.
Perhaps that may also resolve some of these issues for you!?
> @@ -835,10 +844,20 @@ static inline bool msdc_cmd_is_ready(struct msdc_host *host,
> {
> /* The max busy time we can endure is 20ms */
> unsigned long tmo = jiffies + msecs_to_jiffies(20);
> + u32 count = 0;
> +
> + if (in_interrupt()) {
> + while ((readl(host->base + SDC_STS) & SDC_STS_CMDBUSY) &&
> + (count < 1000)) {
> + udelay(1);
> + count++;
This seems like a bad idea, "busy-wait" in irq context is never a good idea.
> + }
> + } else {
> + while ((readl(host->base + SDC_STS) & SDC_STS_CMDBUSY) &&
> + time_before(jiffies, tmo))
> + cpu_relax();
> + }
>
> - while ((readl(host->base + SDC_STS) & SDC_STS_CMDBUSY) &&
> - time_before(jiffies, tmo))
> - cpu_relax();
> if (readl(host->base + SDC_STS) & SDC_STS_CMDBUSY) {
> dev_err(host->dev, "CMD bus busy detected\n");
> host->error |= REQ_CMD_BUSY;
> @@ -846,17 +865,35 @@ static inline bool msdc_cmd_is_ready(struct msdc_host *host,
> return false;
> }
>
> - if (mmc_resp_type(cmd) == MMC_RSP_R1B || cmd->data) {
> - tmo = jiffies + msecs_to_jiffies(20);
> - /* R1B or with data, should check SDCBUSY */
> - while ((readl(host->base + SDC_STS) & SDC_STS_SDCBUSY) &&
> - time_before(jiffies, tmo))
> - cpu_relax();
> - if (readl(host->base + SDC_STS) & SDC_STS_SDCBUSY) {
> - dev_err(host->dev, "Controller busy detected\n");
> - host->error |= REQ_CMD_BUSY;
> - msdc_cmd_done(host, MSDC_INT_CMDTMO, mrq, cmd);
> - return false;
> + if (cmd->opcode != MMC_SEND_STATUS) {
> + count = 0;
> + /* Consider that CMD6 crc error before card was init done,
> + * mmc_retune() will return directly as host->card is null.
> + * and CMD6 will retry 3 times, must ensure card is in transfer
> + * state when retry.
> + */
> + tmo = jiffies + msecs_to_jiffies(60 * 1000);
> + while (1) {
> + if (msdc_card_busy(host->mmc)) {
> + if (in_interrupt()) {
> + udelay(1);
> + count++;
> + } else {
> + msleep_interruptible(10);
> + }
> + } else {
> + break;
> + }
> + /* Timeout if the device never
> + * leaves the program state.
> + */
> + if (count > 1000 || time_after(jiffies, tmo)) {
> + pr_err("%s: Card stuck in programming state! %s\n",
> + mmc_hostname(host->mmc), __func__);
> + host->error |= REQ_CMD_BUSY;
> + msdc_cmd_done(host, MSDC_INT_CMDTMO, mrq, cmd);
> + return false;
> + }
This hole new code is a hack, that shouldn't be needed in the host driver.
I think we need to investigate and fix the issue in the mmc core
layer, to make this work for your host driver. That instead of doing a
work around in the host.
> }
> }
> return true;
> @@ -1070,18 +1107,6 @@ static int msdc_ops_switch_volt(struct mmc_host *mmc, struct mmc_ios *ios)
> return ret;
> }
>
> -static int msdc_card_busy(struct mmc_host *mmc)
> -{
> - struct msdc_host *host = mmc_priv(mmc);
> - u32 status = readl(host->base + MSDC_PS);
> -
> - /* check if any pin between dat[0:3] is low */
> - if (((status >> 16) & 0xf) != 0xf)
> - return 1;
> -
> - return 0;
> -}
> -
> static void msdc_request_timeout(struct work_struct *work)
> {
> struct msdc_host *host = container_of(work, struct msdc_host,
> --
> 1.7.9.5
>
Kind regards
Uffe
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