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

>
>>
>>> 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?

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.

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