> >On 5-10-2010 10:34, Chris Ball wrote: >> Hi David, >> >> On Thu, Sep 30, 2010 at 08:03:14PM -0700, Philip Rakity wrote: >>> From: Philip Rakity <[email protected]> >>> Date: Thu, 30 Sep 2010 15:34:24 -0700 >>> Subject: [PATCH] sdhci: adjust sd 3.0 host controller spec clock divider >>> >>> The sd 3.0 host spec does not require the clock divider to be a power of 2. > >The text and code for sd 3.0 was talking about a multiple of 2, not a power of >2 > >>> Signed-off-by: Philip Rakity <[email protected]> >>> --- >>> drivers/mmc/host/sdhci.c | 8 +++----- >>> 1 files changed, 3 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >>> index 96c7f60..73a94fe 100644 >>> --- a/drivers/mmc/host/sdhci.c >>> +++ b/drivers/mmc/host/sdhci.c >>> @@ -1003,14 +1003,12 @@ static void sdhci_set_clock(struct sdhci_host >>> *host, unsigned int clock) >>> goto out; >>> >>> if (host->version >= SDHCI_SPEC_300) { >>> - /* Version 3.00 divisors must be a multiple of 2. */ >>> if (host->max_clk <= clock) >>> div = 1; >>> else { >>> - for (div = 2; div < SDHCI_MAX_DIV_SPEC_300; div += 2) { >>> - if ((host->max_clk / div) <= clock) >>> - break; >>> - } >>> + div = host->max_clk/clock; >>> + if (host->max_clk % clock) >>> + div++; >If you mean to divide and round up, wouldn't : > >+ div = DIV_ROUND_UP (host->max_clk, clock); > >be nicer and cheaper? nicer -- yes cheaper -- code is executed normally to set the clock for f_min and then for max frequency.
> >Can SDHCI_MAX_DIV_SPEC_300 be dropped safely? I believe so -- code should not be called from mmc layerwith speed lower then f_min nor more then f_max > >(don't have access to the sd 3.0 specs neither) > >Hein >-- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
