Date:	Thu, 26 May 2016 10:23:39 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Jaehoon Chung <jh80.chung@...sung.com>
Cc:	Doug Anderson <dianders@...omium.org>, shawn.lin@...k-chips.com,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	Sonny Rao <sonnyrao@...omium.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Alexandru Stan <amstan@...omium.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: dw_mmc: Consider HLE errors to be data and command
 errors

Hi Jaehoon,

On 2016/5/19 21:07, Jaehoon Chung wrote:
> On 05/19/2016 08:31 PM, Shawn Lin wrote:
>> Hi,
>>
>> On 2016/5/19 1:37, Doug Anderson wrote:
>>> Hi,
>>>
>>> On Wed, May 18, 2016 at 2:14 AM, Shawn Lin <shawn.lin@...k-chips.com> wrote:
>>>> Hi
>>>>
>>>>
>>>> On 2016-5-18 12:12, Doug Anderson wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> On Tue, May 17, 2016 at 6:59 PM, Shawn Lin
>>>>> <shawn.lin@...nel-upstream.org> wrote:
>>>>>>
>>>>>> Could you try this patch to see if you can still find HLE?
>>>>>>
>>>>>> @@ -2356,12 +2356,22 @@ static void dw_mci_cmd_interrupt(struct dw_mci
>>>>>> *host, u32 status)
>>>>>>   static void dw_mci_handle_cd(struct dw_mci *host)
>>>>>>   {
>>>>>>          int i;
>>>>>> +       int present;
>>>>>>
>>>>>>          for (i = 0; i < host->num_slots; i++) {
>>>>>>                  struct dw_mci_slot *slot = host->slot[i];
>>>>>>
>>>>>>                  if (!slot)
>>>>>>                          continue;
>>>>>>
>>>>>> +               present = !(mci_readl(slot->host, CDETECT) & (1 <<
>>>>>> slot->id));
>>>>>> +               if (present)
>>>>>> +                       set_bit(DW_MMC_CARD_PRESENT, &slot->flags);
>>>>>> +               else
>>>>>> +                       clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);
>>>>>
>>>>>
>>>>> No, because we don't use the builtin card detect on veyron.  ;)
>>>>>
>>>>> We use GPIO card detect because we didn't like the way JTAG and SD
>>>>> interacted.  Also on rk3288 the builtin card detect line had the wrong
>>>>> voltage domain (you couldn't detect a card when the IO lines were
>>>>> powered off).  The builtin card detect line is always driven low on
>>>>> veyron.
>>>>
>>>>
>>>> Okay, I see.
>>>>
>>>>>
>>>>>
>>>>> I'm nearly certain that the root cause of my HLE errors is actually
>>>>> related to the same problem addressed by the commit 7c5209c315ea
>>>>> ("mmc: core: Increase delay for voltage to stabilize from 3.3V to
>>>>> 1.8V").  I think that on minnie we're still on the hairy edge and
>>>>> sometimes the line doesn't transition fast enough.
>>>>
>>>>
>>>> Things are not so simple from your details.
>>>>
>>>> I was not enabling SD3.0 support, then I also found HLE sometimes.
>>>> So it seems commit 7c5209c315ea does not contibute to this phenomenon.
>>>
>>> Just to clarify, in my case commit 7c5209c315ea didn't make the
>>> problem worse, but made it better.  Just not better enough.  ;)
>>>
>>>
>>>> The scenario looks like:
>>>> remove sd-card -> mmc_sd_detect -> send status(CMD13) ->power_off ->
>>>> set_ios -> setup_bus -> disabled clk , then HLE irq storm coming
>>>>
>>>> From the code of dw_mci_prepare_command:
>>>> SDMMC_CMD_PRV_DAT_WAIT will not be used for CMD13, so we don't
>>>> wait_busy here, then cmd code is loding into queue of dw_mmc but
>>>> still failing send out because it's in busy?
>>>>
>>>> With my patch, things go well:
>>>> remove sd-card -> clear bit of DW_MMC_CARD_PRESENT  -> send
>>>> status(CMD13) return directly -> power_off -> set_ios -> setup_bus ->
>>>> disable clk
>>>>
>>>> So why should we allow inquiry of card status if we sure the card is
>>>> removed? I mean no any further cmds should be delivered.
>>>
>>> Quite honestly just dealing with the HLE error (my patch or
>>> equivalent) might be a sane solution for the problem you describe.
>>
>> Yes, your patch looks good to me, so it should be merged firstly. :)
>> Then let's push it a bit further more that when HLEs are coming,
>> somethings must be wrong(currently I don't see a obvious clue from
>> the code itself although, I'm prone to think it belongs to the
>> software issue).
>
> We don't know what's main cause for HLE..But i also think it's relevant to SW issue.
> But we need to consider all possibilities..
>
>>
>>
>>>
>>> dw_mmc needs to be able to work with an external card detect GPIO.
>>> It's been part of the dw_mmc driver for a long time and is (in fact)
>>> in use upstream at least by rk3288-veyron.  Any solution that only
>>> works for internal card detect is not enough.  Just handling the HLE
>>> error to deal with the interrupt storm and then letting Linux remove
>>> the card (because of the card detect interrupt) seems totally OK to
>>> me.
>>>
>>
>> Sure, some of rockchip Socs use gpio for CD because they don't
>> have a internal CD, such as RK3036, right?
>>
>>> Note: I'd be very curious if your problems get better if you disable
>>
>> Not at all.
>>
>>> the "grf_force_jtag" bit in the GRF.  If you're using the builtin card
>>> detect and you use the boot default of "grf_force_jtag" then your pins
>>> will be unmuxed behind your back when the card is ejected.  This could
>>> be causing the dw_mmc controller to get confused.
>>
>> Right, grf_force_jtag is also not a friend of mine. :)
>> So I had disabled this function before I was debugging it.
>>
>>>
>>>
>>>> And another question: should we wait busy for cmd13?
>>>
>>> I don't think so.  As I understand it CMD13 uses only the CMD line for
>>> communication and it should be appropriate to send this when the bus
>>> is "busy" (which means that the DATA lines are low).
>>
>> Ahh... take back my question.. I was just considering a wired situation
>> that pins are unmuxed on the background(cmd line as well) when cmd13 is
>> delivering....
>>
>>
>>>
>>> Also: it seems odd that the HLE IRQ storm didn't come right after the
>>> CMD 13 in your description above.  Are you sure it was the CMD 13 that
>>> caused the HLEs, or could it has been something else?
>>
>> Actually no. Any cmds be issued can trigger HLEs, I think, after sd card is removed When I hacked mmc_sd_detecd to send other cmds intead
>> of cmd13.
>>
>> From dw_mmc databook v270a(7.2.3 Clock Programming) we can see:
>> The DWC_mobile_storage loads each of these registers only when the
>> start_cmd bit and the Update_clk_regs_only bit in the CMD register are
>> set. When a command is successfully loaded, the DWC_mobile_storage
>> clears this bit, unless the DWC_mobile_storage already has another
>> command in the queue, at which point it gives an HLE (Hardware Locked
>> Error); for details on HLEs, refer to “Error Handling” on page 233.
>> Software should look for the start_cmd and the Update_clk_regs_only
>> bits, and should also set the wait_prvdata_complete bit to ensure that
>> clock parameters do not change during data transfer.
>>
>> Maybe the cmd is trying to load(or somethings wrong with the
>> controller?) when we disable the clk? That may explain my observation
>> that HLEs came after disabling clk.
>
> I agreed.
>
> To Disable clock, it sends cmd with update_clk_regs_only and wait_prvdata_complete bit.
> I think it's problem..(waiting for prvdata..)
>
> If there are ongoing some data(read/write), then before disabling clock, waiting for completing previous data.
> (But card was already removed, and it couldn't do anything.)
> It's difficult to analyze the HLE..So After applying first, then we can solve this problem, step by step.
>

I saw you send a PR for v4.7-fix to Ulf which didn't include this one.
Do you plan to add it into 4.8 materials? :)

> Best Regards,
> Jaehoon Chung
>
>>
>>
>>>
>>>
>>> -Doug
>>>
>>>
>>>
>>
>>
>
>
>
>


-- 
Best Regards
Shawn Lin

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