Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756090AbZCKNfq (ORCPT ); Wed, 11 Mar 2009 09:35:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753983AbZCKNfX (ORCPT ); Wed, 11 Mar 2009 09:35:23 -0400 Received: from mx1.auerswald.de ([212.185.163.234]:2182 "EHLO mail.auerswald.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752384AbZCKNfW convert rfc822-to-8bit (ORCPT ); Wed, 11 Mar 2009 09:35:22 -0400 From: Wolfgang =?iso-8859-15?q?M=FCes?= Organization: Auerswald GmbH & Co. KG To: Pierre Ossman Subject: [PATCH 6/7] mmc_spi: convert timeout handling to jiffies and avoid busy waiting Date: Wed, 11 Mar 2009 14:35:03 +0100 User-Agent: KMail/1.9.10 Cc: "Andrew Morton" , "Matt Fleming" , "David Brownell" , "Mike Frysinger" , linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200903111435.03196.wolfgang.mues@auerswald.de> Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4889 Lines: 150 From: Wolfgang Muees o SD/MMC card timeouts can be very high. So avoid busy-waiting, using the scheduler. Calculate all timeouts in jiffies units, because this will give us the correct sign when to involve the scheduler. Signed-off-by: Wolfgang Muees --- This is one of a line of patches to enhance the usability of the mmc spi host port driver from "don't work with most SD cards" to "work with nearly all SD cards" (including those ugly cards with non-byte-aligned responses). diff -uprN 2_6_29_rc7_patch5_extra_spi_timeouts/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch6_jiffies_and_scheduling/drivers/mmc/host/mmc_spi.c --- 2_6_29_rc7_patch5_extra_spi_timeouts/drivers/mmc/host/mmc_spi.c 2009-03-11 13:43:39.000000000 +0100 +++ 2_6_29_rc7_patch6_jiffies_and_scheduling/drivers/mmc/host/mmc_spi.c 2009-03-11 13:49:53.000000000 +0100 @@ -24,7 +24,7 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ -#include +#include #include #include #include @@ -95,7 +95,7 @@ * reads which takes nowhere near that long. Older cards may be able to use * shorter timeouts ... but why bother? */ -#define r1b_timeout ktime_set(3, 0) +#define r1b_timeout (HZ * 3) /****************************************************************************/ @@ -183,12 +183,11 @@ mmc_spi_readbytes(struct mmc_spi_host *h return status; } -static int -mmc_spi_skip(struct mmc_spi_host *host, ktime_t timeout, unsigned n, u8 byte) +static int mmc_spi_skip(struct mmc_spi_host *host, unsigned long timeout, + unsigned n, u8 byte) { u8 *cp = host->data->status; - - timeout = ktime_add(timeout, ktime_get()); + unsigned long start = jiffies; while (1) { int status; @@ -203,22 +202,26 @@ mmc_spi_skip(struct mmc_spi_host *host, return cp[i]; } - /* REVISIT investigate msleep() to avoid busy-wait I/O - * in at least some cases. - */ - if (ktime_to_ns(ktime_sub(ktime_get(), timeout)) > 0) + if (time_is_before_jiffies(start + timeout)) break; + + /* If we need long timeouts, we may release the CPU. + * We use jiffies here because we want to have a relation + * between elapsed time and the blocking of the scheduler. + */ + if (time_is_before_jiffies(start+1)) + schedule(); } return -ETIMEDOUT; } static inline int -mmc_spi_wait_unbusy(struct mmc_spi_host *host, ktime_t timeout) +mmc_spi_wait_unbusy(struct mmc_spi_host *host, unsigned long timeout) { return mmc_spi_skip(host, timeout, sizeof(host->data->status), 0); } -static int mmc_spi_readtoken(struct mmc_spi_host *host, ktime_t timeout) +static int mmc_spi_readtoken(struct mmc_spi_host *host, unsigned long timeout) { return mmc_spi_skip(host, timeout, 1, 0xff); } @@ -607,7 +610,7 @@ mmc_spi_setup_data_message( */ static int mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t, - ktime_t timeout) + unsigned long timeout) { struct spi_device *spi = host->spi; int status, i; @@ -712,7 +715,7 @@ mmc_spi_writeblock(struct mmc_spi_host * */ static int mmc_spi_readblock(struct mmc_spi_host *host, struct spi_transfer *t, - ktime_t timeout) + unsigned long timeout) { struct spi_device *spi = host->spi; int status; @@ -802,7 +805,7 @@ mmc_spi_data_do(struct mmc_spi_host *hos unsigned n_sg; int multiple = (data->blocks > 1); u32 clock_rate; - ktime_t timeout; + unsigned long timeout; if (data->flags & MMC_DATA_READ) direction = DMA_FROM_DEVICE; @@ -816,8 +819,11 @@ mmc_spi_data_do(struct mmc_spi_host *hos else clock_rate = spi->max_speed_hz; - timeout = ktime_add_ns(ktime_set(0, 0), data->timeout_ns + - data->timeout_clks * 1000000 / clock_rate); + timeout = data->timeout_ns + + data->timeout_clks * 1000000 / clock_rate; + timeout = usecs_to_jiffies((unsigned int)(timeout / 1000)); + if (!timeout) + timeout = 1; /* Handle scatterlist segments one at a time, with synch for * each 512-byte block --- regards i. A. Wolfgang M?es -- Auerswald GmbH & Co. KG Hardware Development Telefon: +49 (0)5306 9219 0 Telefax: +49 (0)5306 9219 94 E-Mail: Wolfgang.Mues@Auerswald.de Web: http://www.auerswald.de ? -------------------------------------------------------------- Auerswald GmbH & Co. KG, Vor den Grash?fen 1, 38162 Cremlingen Registriert beim AG Braunschweig HRA 13289 p.h.G Auerswald Gesch?ftsf?hrungsges. mbH Registriert beim AG Braunschweig HRB 7463 Gesch?ftsf?hrer: Dipl-Ing. Gerhard Auerswald -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/