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. 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
