Re: [PATCH 05/10] ARM i.MX25: Enable all needed clocks during startup

[Sascha Hauer <s.hauer@pengutronix.de>]

On Mon, Oct 08, 2012 at 10:49:21PM +0200, Roberto Nibali wrote:
> Hi
> 
> >  arch/arm/mach-imx/clk-imx25.c |   16 +++++++++++++---
> >  1 file changed, 13 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/arm/mach-imx/clk-imx25.c b/arch/arm/mach-imx/clk-imx25.c
> > index 3b9588c..3a141c2 100644
> > --- a/arch/arm/mach-imx/clk-imx25.c
> > +++ b/arch/arm/mach-imx/clk-imx25.c
> > @@ -76,9 +76,19 @@ static int imx25_ccm_probe(struct device_d *dev)
> >
> >         base = dev_request_mem_region(dev, 0);
> >
> > -       writel(0x10e88578, base + CCM_CGCR0);
> > -       writel(0x0478e1e0, base + CCM_CGCR0);
> > -       writel(0x0007c400, base + CCM_CGCR0);
> > +       writel((1 << 3) | (1 << 4) | (1 << 5) | (1 << 6) | (1 << 8) | (1 << 9) |
> > +                       (1 << 10) | (1 << 15) | (1 << 19) | (1 << 21) | (1 << 22) |
> > +                       (1 << 22) | (1 << 23) | (1 << 24) | (1 << 28),
> 
> (1<<22) does not need to be written twice, I'm sure the bit is safe in
> silicon :).

Sure ;) Will fix.

> 
> > +                       base + CCM_CGCR0);
> > +
> > +       writel((1 << 5) | (1 << 6) | (1 << 7) | (1 << 8) | (1 << 13) | (1 << 14) |
> > +                       (1 << 15) | (1 << 19) | (1 << 20) | (1 << 21) | (1 << 22) |
> > +                       (1 << 26) | (1 << 29) | (1 << 31),
> > +                       base + CCM_CGCR1);
> > +
> > +       writel((1 << 0) | (1 << 1) | (1 << 2) | (1 << 10) | (1 << 13) | (1 << 14) |
> > +                       (1 << 15) | (1 << 16) | (1 << 17) | (1 << 18),
> > +                       base + CCM_CGCR2);
> 
> Quite a change from writing 0x15692B58 (sum) to CGCR0, enabling PER
> clocks esdhc1, esdhc2, i2c, nfc, owire, sim1, ssi1, and AHB clocks
> ata, emi, esdhc1, esdhc2, lcdc, sdma, usbotg, to now enabling the
> following clocks:
> 
> PER: esdhc1, esdhc2, i2c, nfc, owire, pwm(!), uart (!)
> AHB: emi, esdhc1, esdhc2, fec, lcdc, usbotg
> 
> Why not enable all clocks (i.e. sim1, sim2, ssi1, ssi2)? Maybe because
> we have no drivers (yet)?

I really hope we do not get sound support in barebox...

> Or does it not matter, because each platform
> driver is required to set the clocks anyway in the init routine?

No, the strategy I want to follow is that we enable all necessary clocks
for barebox during startup. Barebox normally does not run long enough to
waste a significant amount og energy. The kernel will turn of the
unneeded clocks anyway, so I think it's just not worth the effort (and
binary size) to add proper clk gate support.

> 
> With regard to CGCR1 and CGCR2, the following clock outputs get
> enabled (maybe for changelog):
> 
> IPG: cspi1, cspi2, cspi3, esdhc1, esdhc2, fec, gpt1, gpt2, gpt3, gpt4,
> iim, LCDC_EN, pwm1, pwm2, pwm3, pwm4, spba, tsc, uart1, uart2, uart3,
> uart4, uart5.

Ok, can add this.

Thanks
  Sascha

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