Re: [PATCH v3 5/6] ARM: shmobile: lager: Set clock rates for SDHI

[Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>]

On Tue, 2015-06-30 at 02:29 +0100, Ben Hutchings wrote:
> On Tue, 2015-06-30 at 01:02 +0100, Ben Hutchings wrote:
> > On Mon, 2015-06-29 at 06:23 +0000, Kuninori Morimoto wrote:
> [...]
> > > If so, why we can't use max-frequency ?
> > > We can calculate/set SDHI IP clocks via 
> > > max-frequency / clk_round_rate() / clk_set_rate()
> > > since we know SDHI's divider capability.
> > > 
> > > SH-MMC is using this style. and I think it is flexible for every speed.
> > > Please check sh_mmcif_clock_control(), sh_mmcif_clk_setup()
> > > on ${LINUX}/drivers/mmc/host/sh_mmcif.c
> > 
> > That's certainly a nicer way of doing this.  The difficulty I see is
> > that tmio_mmc doesn't know anything about the input clock, and not all
> > of the drivers using it actually use the clock framework.
> 
> More importantly, that algrithm can result in overclocking the card.

...and some of the multiplications overflow!

Ben.


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