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? > cheers, > 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/ > >> > > > > > > -- > EC No. > -- 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
