From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH] mmc: core: don't return 1 for max_discard Date: Thu, 19 Dec 2013 11:01:19 +0200 Message-ID: <52B2B5DF.1020702@intel.com> References: <1387405663-14253-1-git-send-email-swarren@wwwdotorg.org> <52B22906.4010704@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52B22906.4010704-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: Chris Ball , linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stephen Warren , Dong Aisheng , Ulf Hansson , Vladimir Zapolskiy List-Id: linux-tegra@vger.kernel.org On 19/12/13 01:00, Stephen Warren wrote: > On 12/18/2013 03:27 PM, Stephen Warren wrote: >> From: Stephen Warren >> >> In mmc_do_calc_max_discard(), if only a single erase block can be >> discarded within the host controller's timeout, don't allow discard >> operations at all. >> >> Previously, the code allowed sector-at-a-time discard (rather than >> erase-block-at-a-time), which was chronically slow. >> >> Without this patch, on the NVIDIA Tegra Cardhu board, the loops result >> in qty == 1, which is immediately returned. This causes discard to >> operate a single sector at a time, which is chronically slow. With this >> patch in place, discard operates a single erase block at a time, which >> is reasonably fast. > > Alternatively, is the real fix a revert of e056a1b5b67b "mmc: queue: let > host controllers specify maximum discard timeout", followed by: > >> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c >> index 050eb262485c..35c5b5d86c99 100644 >> --- a/drivers/mmc/core/core.c >> +++ b/drivers/mmc/core/core.c >> @@ -1950,7 +1950,6 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from, >> cmd.opcode = MMC_ERASE; >> cmd.arg = arg; >> cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC; >> - cmd.cmd_timeout_ms = mmc_erase_timeout(card, arg, qty); >> err = mmc_wait_for_cmd(card->host, &cmd, 0); >> if (err) { >> pr_err("mmc_erase: erase error %d, status %#x\n", >> @@ -1962,7 +1961,7 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from, >> if (mmc_host_is_spi(card->host)) >> goto out; >> >> - timeout = jiffies + msecs_to_jiffies(MMC_CORE_TIMEOUT_MS); >> + timeout = jiffies + msecs_to_jiffies(mmc_erase_timeout(card, arg, qty)); >> do { >> memset(&cmd, 0, sizeof(struct mmc_command)); >> cmd.opcode = MMC_SEND_STATUS; > > That certainly also seems to solve the problem on my board... But large erases will timeout when they should have been split into smaller chunks. A generic solution needs to be able to explain what happens when the host controller *does* timeout.