RE: [PATCH 6/7] pm: at91: add achieve the mpddrc peripheral ID and the DDR clock ID support

["Yang, Wenyou" <Wenyou.Yang@atmel.com>]

Hi Mark,

Thank you for your review.

> -----Original Message-----
> From: Mark Rutland [mailto:mark.rutland@arm.com]
> Sent: Monday, January 26, 2015 7:50 PM
> To: Yang, Wenyou
> Cc: Ferre, Nicolas; linux@arm.linux.org.uk; sylvain.rochet@finsecur.com; Vilchez,
> Patrice; linux-kernel@vger.kernel.org; alexandre.belloni@free-electrons.com;
> peda@axentia.se; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH 6/7] pm: at91: add achieve the mpddrc peripheral ID and the
> DDR clock ID support
> 
> On Mon, Jan 26, 2015 at 10:08:16AM +0000, Wenyou Yang wrote:
> > The patch achieves the mpddr controller peripheral ID and the DDR
> > clock ID from the dts file.
> >
> > They will be used in the future to disable the mpddr controller'c
> > clock the and DDR clock to decrease the power consumption during suspending.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
> > ---
> >  arch/arm/mach-at91/generic.h |    2 ++
> >  arch/arm/mach-at91/setup.c   |   24 ++++++++++++++++++++++++
> >  2 files changed, 26 insertions(+)
> >
> > diff --git a/arch/arm/mach-at91/generic.h
> > b/arch/arm/mach-at91/generic.h index 41796bf..3c72a3e 100644
> > --- a/arch/arm/mach-at91/generic.h
> > +++ b/arch/arm/mach-at91/generic.h
> > @@ -47,6 +47,8 @@ void __init at91_sam9x5_pm_init(void) { }  struct
> > at91_pm_struct {
> >  	unsigned long uhp_udp_mask;
> >  	int memctrl;
> > +	u32 mpddrc_id[2];
> > +	u32 ddrck_id;
> >  };
> >
> >  #endif /* _AT91_GENERIC_H */
> > diff --git a/arch/arm/mach-at91/setup.c b/arch/arm/mach-at91/setup.c
> > index 7924663..a306f95 100644
> > --- a/arch/arm/mach-at91/setup.c
> > +++ b/arch/arm/mach-at91/setup.c
> > @@ -363,6 +363,27 @@ void __init at91_ioremap_matrix(u32 base_addr)
> >  		panic(pr_fmt("Impossible to ioremap at91_matrix_base\n"));  }
> >
> > +static u32 at91_of_get_ddr_id(struct device_node *np, char *name) {
> > +	struct of_phandle_args clkspec;
> > +	u32 id;
> > +	int index;
> > +	int rc;
> > +
> > +	index = of_property_match_string(np, "clock-names", name);
> > +	rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
> &clkspec);
> > +	if (rc)
> > +		return 0;
> > +
> > +	rc = of_property_read_u32(clkspec.np, "reg", &id);
> > +	if (rc)
> > +		return 0;
> > +
> > +	of_node_put(clkspec.np);
> > +
> > +	return id;
> > +}
> 
> This doesn't look right to me. This assumes the format of the clock provider node,
> which invalidates the point of having the abstraction in the first place.
> 
> > +
> >  struct at91_ramc_of_data {
> >  	u8 ramc_type;
> >  };
> > @@ -400,6 +421,9 @@ static void at91_dt_ramc(void)
> >  		of_data = of_id->data;
> >  		at91_pm_data.memctrl = of_data->ramc_type;
> >
> > +		at91_pm_data.mpddrc_id[idx] = at91_of_get_ddr_id(np, "mpddr");
> > +		at91_pm_data.ddrck_id = at91_of_get_ddr_id(np, "ddrck");
> > +
> 
> Why do you need these here?
> 
> Surely the logic for poking any clocks should live in the relevant clock controller
> drivers?
Thank for your suggestion.

I thought that it is reasonable to get the DDR controller's peripheral id from the DDR device node.

Anyway, let me think over how to do it.

> 
> Mark.

Best Regards,
Wenyou Yang