For what its worth, I applied these two patches and the huge delay in
mkfs.ext3
(when run on SABRESD-resident eMMC) is gone; however, based on the
discussion,
it appears this isn't the *final* change, is that true?
Thanks,
Ed
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?
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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