The patch titled spi_s3c24xx: fix clock rate calculation has been added to the -mm tree. Its filename is spi_s3c24xx-fix-clock-rate-calculation.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: spi_s3c24xx: fix clock rate calculation From: Ben Dooks <ben@xxxxxxxxxxxx> Currently the clock rate calculation may round as pleased, which means that it is possible that we will round down and end up with a faster clock rate than intended. Change the calculation to use DIV_ROUND_UP() to ensure that we end up with a clock rate either the same as or lower than the user requested one. Signed-off-by: Ben Dooks <ben@xxxxxxxxxxxx> Cc: David Brownell <david-b@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/spi/spi_s3c24xx.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff -puN drivers/spi/spi_s3c24xx.c~spi_s3c24xx-fix-clock-rate-calculation drivers/spi/spi_s3c24xx.c --- a/drivers/spi/spi_s3c24xx.c~spi_s3c24xx-fix-clock-rate-calculation +++ a/drivers/spi/spi_s3c24xx.c @@ -111,6 +111,7 @@ static int s3c24xx_spi_setupxfer(struct unsigned int bpw; unsigned int hz; unsigned int div; + unsigned long clk; bpw = t ? t->bits_per_word : spi->bits_per_word; hz = t ? t->speed_hz : spi->max_speed_hz; @@ -120,20 +121,16 @@ static int s3c24xx_spi_setupxfer(struct return -EINVAL; } - div = clk_get_rate(hw->clk) / hz; - - /* is clk = pclk / (2 * (pre+1)), or is it - * clk = (pclk * 2) / ( pre + 1) */ - - div /= 2; - - if (div > 0) - div -= 1; + clk = clk_get_rate(hw->clk); + div = DIV_ROUND_UP(clk, hz * 2) - 1; if (div > 255) div = 255; - dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", div, hz); + dev_dbg(&spi->dev, "setting pre-scaler to %d (wanted %d, got %ld)\n", + div, hz, clk / (2 * (div + 1))); + + writeb(div, hw->regs + S3C2410_SPPRE); spin_lock(&hw->bitbang.lock); _ Patches currently in -mm which might be from ben@xxxxxxxxxxxx are linux-next.patch spi-fix-spelling-of-automatically-in-documentation.patch spi_s3c24xx-fix-clock-rate-calculation.patch spi_s3c24xx-fix-transfer-setup-code.patch spi_s3c24xx-fix-header-includes.patch spi_s3c24xx-use-resource_size-to-get-resource-size.patch spi_s3c24xx-use-dev_pm_ops.patch spi_s3c24xx-cache-device-setup-data.patch gpiolib-add-names-file-in-gpio-chip-sysfs.patch gpiolib-add-names-file-in-gpio-chip-sysfs-checkpatch-fixes.patch gpiolib-add-names-file-in-gpio-chip-sysfs-checkpatch-fixes-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html