On 22/11/13 17:21, Vladimir Zapolskiy wrote:
> On 22.11.2013 16:04, Adrian Hunter wrote:
>> On 22/11/13 15:50, Vladimir Zapolskiy wrote:
>>> On 22.11.2013 14:04, Adrian Hunter wrote:
>>>> On 22/11/13 14:24, Vladimir Zapolskiy wrote:
>>>>> On 22.11.2013 12:38, Adrian Hunter wrote:
>>>>>> On 21/11/13 17:07, Vladimir Zapolskiy wrote:
>>>>>>> JEDEC specification defines quite high erase timeout value for 300ms
>>>>>>> multiplied by erase group number, and SD Host Controller specification
>>>>>>> data line timeout may be much less, e.g. 2^13 / 52MHz ~ 160us.
>>>>>>>
>>>>>>>> From block layer and MMC perfromance perspective it is desirable
>>>>>>>> that
>>>>>>> millions of erase groups are discarded at once, so there is no much
>>>>>>> sense to limit maximum erase timeout by data line timeout, if a
>>>>>>> controller handles correctly erase operation without indication of
>>>>>>> data line timeout.
>>>>>>
>>>>>> Would you explain that some more. Do you mean that:
>>>>>> a) it does not have a timeout
>>>>>
>>>>> JEDEC defines a timeout on erase/trim operations, also in
>>>>> drivers/mmc/core/core.c
>>>>> there is a reasonable enough 10 minutes limitation for discard operations.
>>>>>
>>>>>> b) it has a timeout which is less than the timeout specified by the
>>>>>> standard but the operation nevertheless completes
>>>>>
>>>>> SDHC data line timeout is enormously less than erase group timeout, and
>>>>> trivial testing shows that those two timeouts are independent, probably
>>>>> except some particular cases of controllers not known before commits
>>>>> 58d1246db3 and e056a1b5b.
>>>>>
>>>>> According to the currently implemented logic, mmc_do_erase() commonly is
>>>>> instructed to discard 1-2 erase groups at maximum, however it tends to be
>>>>> capable to successfully discard millions of erase groups at once ignoring
>>>>> that SDHC data line timeout limitation.
>>>>>
>>>>
>>>> You seem to be trying to say that the SDHCI spec. says that the host
>>>> controller does not timeout erase operations or uses a different timeout
>>>> than the one programmed in the "Timeout Control Register". Where is
>>>> that is
>>>> the SDHCI spec?
>>>
>>> According to the spec a host controller timeouts erase operations like any
>>> other R1B command.
>>>
>>> So in your opinion, should there be SDHCI_QUIRK_BROKEN_TIMEOUT_VAL instead
>>> of the new quirk?
>>
>> I don't understand how SDHCI_QUIRK_BROKEN_TIMEOUT_VAL would help. It just
>> sets the timeout to maximum but max_discard_to is the maximum timeout.
>
> Here I meant to do something like:
>
> if (host->quirks & SDHCI_QUIRK_BROKEN_TIMEOUT_VAL)
> mmc->max_discard_to = 0;
>
> Again I'm not sure that this applies well to all SDHCI_QUIRK_BROKEN_TIMEOUT_VAL
> controllers, therefore a new quirk might be better.
>
>> As I understand it you don't want to limit the discard size, either because
>> your controller does not timeout, or because you are happy that the maximum
>> timeout is enough for your users and their use-cases.
>>
>> If that is the case then the original patch just needs the quirk the other
>> way around. i.e.
>>
>> if (host->quirks2& SDHCI_QUIRK2_NO_DISCARD_LIMIT)
>> mmc->max_discard_to = 0;
>> else
>> mmc->max_discard_to = (1<< 27) / host->timeout_clk;
>
> This suits me fine, thanks for review, and I'll resend a change based on this.
>
> Also I'd like to pay your attention to (1 << 27) / host->timeout_clk part of
> calculation, following the spec it might be better to account the actual
> value of Data Timeout Counter, otherwise a controller may get unintentional
> Data Timeout Error pretty soon. Please correct me, if I'm mistaken here.
Not sure what you mean. max_discard_to is the maximum timeout (in
milliseconds) that the host controller supports. The intent is to limit
erase operations to ones that have a timeout that is less than or equal to that.
Currently, the limit gets applied by the block layer before the mmc layer is
involved so there is no possibility to take the actual timeout into account.
However if you have erase_group_def set, then it won't make any difference
i.e. the limit will be the same.
>
>>>
>>>>>>>
>>>>>>> Potentially the change may break some of the SDHCs on discard of mmc,
>>>>>>> and for backward compatibility a new quirk is introduced, which is NOT
>>>>>>> set by default.
>>>>>>
>>>>>> It sounds to me that what you want to do is not standard so the quirk
>>>>>> should
>>>>>> be the other way around.
>>>>>
>>>>> Please take a look at commits 58d1246db3 and e056a1b5b, I'd be glad, if
>>>>> you
>>>>> could elaborate to which "some host controllers" the quirk in my
>>>>> definition
>>>>> applies, I believe all other host controllers present at that time in
>>>>> drivers/mmc/host/* are capable to discard without introduced limitation.
>>>>
>>>> "some host controllers" == SDHCI i.e. to all of the ones you are applying
>>>> the change.
>>>>
>>>>>
>>>>>>>
>>>>>>> Signed-off-by: Vladimir Zapolskiy<vladimir_zapolskiy@xxxxxxxxxx>
>>>>>>> Reported-by: Ed Sutter<ed.sutter@xxxxxxxxxxxxxxxxxx>
>>>>>>> Cc: Chris Ball<cjb@xxxxxxxxxx>
>>>>>>> Cc: Adrian Hunter<adrian.hunter@xxxxxxxxx>
>>>>>>> ---
>>>>>>> drivers/mmc/host/sdhci.c | 5 ++++-
>>>>>>> include/linux/mmc/sdhci.h | 1 +
>>>>>>> 2 files changed, 5 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>>>>>> index bd8a098..b1fdddb 100644
>>>>>>> --- a/drivers/mmc/host/sdhci.c
>>>>>>> +++ b/drivers/mmc/host/sdhci.c
>>>>>>> @@ -2930,7 +2930,10 @@ int sdhci_add_host(struct sdhci_host *host)
>>>>>>> if (host->quirks& SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
>>>>>>> host->timeout_clk = mmc->f_max / 1000;
>>>>>>>
>>>>>>> - mmc->max_discard_to = (1<< 27) / host->timeout_clk;
>>>>>>> + if (host->quirks2& SDHCI_QUIRK2_DATA_TIMEOUT_ON_DISCARD)
>>>>>>> + mmc->max_discard_to = (1<< 27) / host->timeout_clk;
>>>>>>> + else
>>>>>>> + mmc->max_discard_to = 0;
>>>>>>>
>>>>>>> mmc->caps |= MMC_CAP_SDIO_IRQ | MMC_CAP_ERASE | MMC_CAP_CMD23;
>>>>>>>
>>>>>>> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
>>>>>>> index 3e781b8..e7f6bd2 100644
>>>>>>> --- a/include/linux/mmc/sdhci.h
>>>>>>> +++ b/include/linux/mmc/sdhci.h
>>>>>>> @@ -98,6 +98,7 @@ struct sdhci_host {
>>>>>>> #define SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON (1<<4)
>>>>>>> /* Controller has a non-standard host control register */
>>>>>>> #define SDHCI_QUIRK2_BROKEN_HOST_CONTROL (1<<5)
>>>>>>> +#define SDHCI_QUIRK2_DATA_TIMEOUT_ON_DISCARD (1<<6)
>>>>>>>
>>>>>>> int irq; /* Device IRQ */
>>>>>>> void __iomem *ioaddr; /* Mapped address */
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>
>
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