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SubjectRe: [PATCH] mmc: host: sdhci: Fix the incorrect soft reset operation when runtime resuming
Hi Adrian,

On Mon, 15 Jul 2019 at 20:39, Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 15/07/19 2:37 PM, Baolin Wang wrote:
> > Hi Adrian,
> >
> > On Mon, 15 Jul 2019 at 19:20, Adrian Hunter <adrian.hunter@intel.com> wrote:
> >>
> >> On 15/07/19 1:58 PM, Baolin Wang wrote:
> >>> In sdhci_runtime_resume_host() function, we will always do software reset
> >>> for all, but according to the specification, we should issue reset command
> >>> and reinitialize the SD/eMMC card.
> >>
> >> Where does it say that?
> >
> > I checked the SD host controller simplified specification Ver4.20, and
> > in Page 75, Software Reset For All bit, it says "if this bit is set
> > to1, the host driver should issue reset command and reinitialize the
> > SD card". (I did not check other versions).
>
> That might simply be assuming that the bus power also controls the card power.

Yes.

>
> >
> >>
> >>> However, we only do reinitialize the
> >>> SD/eMMC card when the SD/eMMC card are power down during runtime suspend.
> >>>
> >>> Thus for those platforms that do not power down the SD/eMMC card during
> >>> runtime suspend, we should not do software reset for all.
> >>> To fix this
> >>> issue, we can add one condition to validate the MMC_CAP_AGGRESSIVE_PM
> >>> to decide if we can do software reset for all or just reset command
> >>> and data lines.
> >>>
> >>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> >>> ---
> >>> drivers/mmc/host/sdhci.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> >>> index 9715834..470c5e0 100644
> >>> --- a/drivers/mmc/host/sdhci.c
> >>> +++ b/drivers/mmc/host/sdhci.c
> >>> @@ -3333,7 +3333,7 @@ int sdhci_runtime_resume_host(struct sdhci_host *host)
> >>> host->ops->enable_dma(host);
> >>> }
> >>>
> >>> - sdhci_init(host, 0);
> >>> + sdhci_init(host, !(mmc->caps & MMC_CAP_AGGRESSIVE_PM));
> >>
> >> We have done a full reset for a long time, so it would be surprising to need
> >> to change it.
> >>
> >> What problem is it causing?
> >
> > If we did not power down the SD card during runtime suspend, and we
> > reset for all when runtime resume, our SD host controller can not work
> > well, will meet some strange behavior, like:
> >
> > [ 6.525397] mmc0: Got data interrupt 0x00000002 even though no data
> > operation was in progress.
> > [ 6.534189] mmc0: sdhci: ============ SDHCI REGISTER DUMP ===========
> > [ 6.540797] mmc0: sdhci: Sys addr: 0x00000008 | Version: 0x00000004
> > [ 6.547413] mmc0: sdhci: Blk size: 0x00000200 | Blk cnt: 0x00000000
> > [ 6.554029] mmc0: sdhci: Argument: 0x03200101 | Trn mode: 0x00000033
> > [ 6.560645] mmc0: sdhci: Present: 0x01f000f0 | Host ctl: 0x00000030
> > [ 6.567262] mmc0: sdhci: Power: 0x00000000 | Blk gap: 0x00000000
> > [ 6.573877] mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x00000007
> > [ 6.580493] mmc0: sdhci: Timeout: 0x0000000e | Int stat: 0x00000000
> > [ 6.587109] mmc0: sdhci: Int enab: 0x037f000b | Sig enab: 0x037f000b
> > [ 6.593726] mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000
> > [ 6.600342] mmc0: sdhci: Caps: 0x1c6d0080 | Caps_1: 0x08000007
> > [ 6.606959] mmc0: sdhci: Cmd: 0x0000061b | Max curr: 0x00ffffff
> > [ 6.613574] mmc0: sdhci: Resp[0]: 0x00001201 | Resp[1]: 0x00000000
> > [ 6.620190] mmc0: sdhci: Resp[2]: 0x00000000 | Resp[3]: 0x00000000
> > [ 6.626806] mmc0: sdhci: Host ctl2: 0x00003807
> > [ 6.631364] mmc0: sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x00000000df062000
> > [ 6.638697] mmc0: sdhci: ============================================
> > [ 6.645379] mmc0: cache flush error -84
> >
> > Got data interrupt but no data commands are processing now. With this
> > patch, then our SD host controller can work well. Did I miss anything
> > else? Thanks.
>
> The response seems to show the card in state 9 bus-testing, which would
> suggest the use of CMD19 for eMMC. Perhaps the wrong command is used for
> eMMC re-tuning?

So it is strange, for eMMC we use CMD21 for tuning.

>
> The difficulty with changing long standing flow is that it might reveal
> problems for other existing hardware. Did you consider making a
> driver-specific change? The ->reset() callback could be used.

Understood. I will find a way to fix my issue and do not affect the
original logic used by other hardware. Thanks.

--
Baolin Wang
Best Regards

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