From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH] mmc: sdhci: don't limit discard timeout by data line timeout Date: Fri, 22 Nov 2013 15:04:35 +0200 Message-ID: <528F5663.2050800@intel.com> References: <1385046445-29711-1-git-send-email-vladimir_zapolskiy@mentor.com> <528F4242.8040408@intel.com> <528F4D06.3080400@mentor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mga01.intel.com ([192.55.52.88]:6184 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752132Ab3KVM5M (ORCPT ); Fri, 22 Nov 2013 07:57:12 -0500 In-Reply-To: <528F4D06.3080400@mentor.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Vladimir Zapolskiy Cc: linux-mmc@vger.kernel.org, Ed Sutter , Chris Ball 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 >>> Reported-by: Ed Sutter >>> Cc: Chris Ball >>> Cc: Adrian Hunter >>> --- >>> 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 */ >>> >> > >