Re: [PATCH v2 1/2] mmc: dw_mmc: fix bug that cause 'Timeout sending command'

From: Andrzej Hajda
Date: Wed Feb 11 2015 - 06:58:41 EST

Hi Alim,

On 02/11/2015 03:57 AM, Addy wrote:
>
> On 2015/02/10 23:22, Alim Akhtar wrote:
>> Hi Addy,
>>
>> On Mon, Feb 9, 2015 at 12:55 PM, Addy Ke <addy.ke@xxxxxxxxxxxxxx> 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 <addy.ke@xxxxxxxxxxxxxx>
>>> ---
>>> 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);
>>> +
>> Why 500 msec?
> This timeout value is the same as mci_send_cmd:
> static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg)
> {
> struct dw_mci *host = slot->host;
> unsigned long timeout = jiffies + msecs_to_jiffies(500);
> ....
> }
>
> I have not clear that which is suitable.
> Do you have any suggestion on it?
>>
>>> + 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);
>>> +
>> Why you need to reset all blocks? may be CTRL_RESET is good enough here.
> I have tested on rk3288, if only reset ctroller, data busy bit will not
> be cleaned,and we will still get
>
> "Timeout sending command".
>
>>
>>> + /* 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);
>>>
>> hmm...I would suggest you to call dw_mci_wait_busy() from inside
>> mci_send_cmd(), seems like dw_mmc hangs while sending update clock cmd
>> in multiple cases.see [1]
>>
>> [1]: http://permalink.gmane.org/gmane.linux.kernel.mmc/31140
> I think this patch is more reasonable.
> So I will resend patches based on this patch.
> thank you!

I have tested your patches instead [1] above and they do not solve my issue:
Board: odroid-xu3/exynos5422/dw_mmc_250a.
MMC card: absent, broken-cd quirk
SD card: present

System hangs during boot after few minutes kernel spits:
[ 242.188098] INFO: task kworker/u16:1:50 blocked for more than 120
seconds.
[ 242.193524] Not tainted
3.19.0-next-20150210-00002-gf96831b-dirty #3834
[ 242.200622] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[ 242.208422] kworker/u16:1 D c04766ac 0 50 2 0x00000000
[ 242.214756] Workqueue: kmmcd mmc_rescan
[ 242.218553] [<c04766ac>] (__schedule) from [<c0476a58>]
(schedule+0x34/0x98)
[ 242.225591] [<c0476a58>] (schedule) from [<c047a4dc>]
(schedule_timeout+0x110/0x164)
[ 242.233302] [<c047a4dc>] (schedule_timeout) from [<c04774f0>]
(wait_for_common+0xb8/0x14c)
[ 242.241539] [<c04774f0>] (wait_for_common) from [<c0362138>]
(mmc_wait_for_req+0x68/0x17c)
[ 242.249861] [<c0362138>] (mmc_wait_for_req) from [<c03622cc>]
(mmc_wait_for_cmd+0x80/0xa0)
[ 242.258002] [<c03622cc>] (mmc_wait_for_cmd) from [<c0367e50>]
(mmc_go_idle+0x78/0xf8)
[ 242.265796] [<c0367e50>] (mmc_go_idle) from [<c0363e2c>]
(mmc_rescan+0x280/0x314)
[ 242.273253] [<c0363e2c>] (mmc_rescan) from [<c0034764>]
(process_one_work+0x120/0x324)
[ 242.281135] [<c0034764>] (process_one_work) from [<c00349cc>]
(worker_thread+0x30/0x42c)
[ 242.289194] [<c00349cc>] (worker_thread) from [<c003926c>]
(kthread+0xd8/0xf4)
[ 242.296389] [<c003926c>] (kthread) from [<c000e7c0>]
(ret_from_fork+0x14/0x34)

Just for record, Exynos4412/dw_mmc_240a with the same configuration
(no MMC card, broken-cd) works OK without patches.


Regards
Andrzej

>>
>>> if (!clock) {
>>> mci_writel(host, CLKENA, 0);
>>> --
>>> 1.8.3.2
>>>
>>>
>>>
>>> _______________________________________________
>>> linux-arm-kernel mailing list
>>> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>>
>
>
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