Hi Simon-san (2012/03/26 14:52), Simon Horman wrote: > On Mon, Mar 26, 2012 at 02:45:30PM +0900, Yusuke Goda wrote: >> Hi Simon-san, Guennadi-san >> >> (2012/03/26 7:30), Simon Horman wrote: >>> On Sat, Mar 24, 2012 at 07:06:31PM +0100, Guennadi Liakhovetski wrote: >>>> On Wed, 21 Mar 2012, Simon Horman wrote: >>>> >>>>> mmc->f_max should be half of the bus clock. >>>>> And now that mmc->f_max is not equal to the bus clock the >>>>> latter should be used directly to calculate mmc->f_min. >>>> >>>> The patch seems correct as it stands, however, looking at it - does anyone >>>> understands why that "close to 400kHz" comment and such a complicated >>>> calculation? Shouldn't it be just host->clk / 512 always? Maybe this >>>> should be a separate patch, so, for this one >>>> >>>> Acked-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> >>> >>> Hi Guennadi, >>> >>> that code seems to date back to the original driver submission >>> made by Goda-san. I have CCed him as perhaps he recalls why >>> the code is like it is. >> I thought to get closer to 400kHz if possible. >> Probably even host->clk / 512 does not have any problem. > > Sorry for my ignorance, is ~400kHz desirable for some reason? Initialization time becomes short. Thanks Goda >>>>> Cc: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> >>>>> Tested-by: Cao Minh Hiep <hiepcm@xxxxxxxxx> >>>>> Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx> >>>>> --- >>>>> drivers/mmc/host/sh_mmcif.c | 12 ++++++------ >>>>> 1 files changed, 6 insertions(+), 6 deletions(-) >>>>> >>>>> diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c >>>>> index 5014bc4..1410baa 100644 >>>>> --- a/drivers/mmc/host/sh_mmcif.c >>>>> +++ b/drivers/mmc/host/sh_mmcif.c >>>>> @@ -1297,14 +1297,14 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev) >>>>> spin_lock_init(&host->lock); >>>>> >>>>> mmc->ops = &sh_mmcif_ops; >>>>> - mmc->f_max = host->clk; >>>>> + mmc->f_max = host->clk / 2; >>>>> /* close to 400KHz */ >>>>> - if (mmc->f_max < 51200000) >>>>> - mmc->f_min = mmc->f_max / 128; >>>>> - else if (mmc->f_max < 102400000) >>>>> - mmc->f_min = mmc->f_max / 256; >>>>> + if (host->clk < 51200000) >>>>> + mmc->f_min = host->clk / 128; >>>>> + else if (host->clk < 102400000) >>>>> + mmc->f_min = host->clk / 256; >>>>> else >>>>> - mmc->f_min = mmc->f_max / 512; >>>>> + mmc->f_min = host->clk / 512; >>>>> if (pd->ocr) >>>>> mmc->ocr_avail = pd->ocr; >>>>> mmc->caps = MMC_CAP_MMC_HIGHSPEED; >>>>> -- >>>>> 1.7.6.3 >>>>> >>>> >>>> --- >>>> Guennadi Liakhovetski, Ph.D. >>>> Freelance Open-Source Software Developer >>>> http://www.open-technology.de/ >>>> >>> >>> >> -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
