Re: [PATCH] mmc: dw_mmc: Consider HLE errors to be data and command errors

[Shawn Lin]

Hi

On 2016-5-18 12:12, Doug Anderson wrote:
> Hi,
>
> On Tue, May 17, 2016 at 6:59 PM, Shawn Lin
> <shawn.lin@xxxxxxxxxxxxxxxxxxx> 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.

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.

And another question: should we wait busy for cmd13?

> It appears that increasing this to 30ms avoids the HLE errors.
>
> I _think_ I can actually fully fix this properly by temporarily
> engaging the internal pull-ups while the voltage switch is happening.
> This will bleed away the voltage just a little bit faster (since lines
> are driven low here).  I'll try to confirm that.
>
>
> In any case, it seems like we should take this patch since (without
> this patch) the failure case when you get HLE errors is that the
> interrupt controller fires over and over again (with no printouts) and
> your system stalls with no error messages.

Sure, at least we need to address this irq storm...

> -Doug