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Date: Wed, 14 Jan 2015 21:21:39 +0100
From: Boris Brezillon <boris.brezillon@...e-electrons.com>
To: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
Cc: Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
Nicolas Ferre <nicolas.ferre@...el.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] ARM: at91: pm: rework cpu detection
Hi Jean-Christophe,
On Wed, 14 Jan 2015 20:14:12 +0100
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com> wrote:
> On 22:23 Mon 12 Jan , Alexandre Belloni wrote:
> > Store SoC differences in a struct to remove cpu_is_* usage.
> >
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> > ---
> > arch/arm/mach-at91/pm.c | 54 ++++++++++++++++++++++++++++++-------------------
> > 1 file changed, 33 insertions(+), 21 deletions(-)
> >
> > diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
> > index 9b15169a1c62..79aa793d1f00 100644
> > --- a/arch/arm/mach-at91/pm.c
> > +++ b/arch/arm/mach-at91/pm.c
> > @@ -17,6 +17,7 @@
> > #include <linux/interrupt.h>
> > #include <linux/sysfs.h>
> > #include <linux/module.h>
> > +#include <linux/of.h>
> > #include <linux/platform_device.h>
> > #include <linux/io.h>
> > #include <linux/clk/at91_pmc.h>
> > @@ -32,6 +33,11 @@
> > #include "generic.h"
> > #include "pm.h"
> >
> > +static struct {
> > + unsigned long uhp_udp_mask;
> > + int memctrl;
> > +} at91_pm_data;
> > +
> > static void (*at91_pm_standby)(void);
> >
> > static int at91_pm_valid_state(suspend_state_t state)
> > @@ -71,17 +77,9 @@ static int at91_pm_verify_clocks(void)
> > scsr = at91_pmc_read(AT91_PMC_SCSR);
> >
> > /* USB must not be using PLLB */
> > - if (cpu_is_at91rm9200()) {
> > - if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
> > - pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
> > - return 0;
> > - }
> > - } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()
> > - || cpu_is_at91sam9g20() || cpu_is_at91sam9g10()) {
> > - if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
> > - pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
> > - return 0;
> > - }
> > + if ((scsr & at91_pm_data.uhp_udp_mask) != 0) {
> > + pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
> > + return 0;
> > }
> >
> > /* PCK0..PCK3 must be disabled, or configured to use clk32k */
> > @@ -149,18 +147,13 @@ static int at91_pm_enter(suspend_state_t state)
> > * turning off the main oscillator; reverse on wakeup.
> > */
> > if (slow_clock) {
> > - int memctrl = AT91_MEMCTRL_SDRAMC;
> > -
> > - if (cpu_is_at91rm9200())
> > - memctrl = AT91_MEMCTRL_MC;
> > - else if (cpu_is_at91sam9g45())
> > - memctrl = AT91_MEMCTRL_DDRSDR;
> > #ifdef CONFIG_AT91_SLOW_CLOCK
> > /* copy slow_clock handler to SRAM, and call it */
> > memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
> > #endif
> > slow_clock(at91_pmc_base, at91_ramc_base[0],
> > - at91_ramc_base[1], memctrl);
> > + at91_ramc_base[1],
> > + at91_pm_data.memctrl);
> > break;
> > } else {
> > pr_info("AT91: PM - no slow clock mode enabled ...\n");
> > @@ -237,10 +230,29 @@ static int __init at91_pm_init(void)
> >
> > pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
> >
> > - /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
> > - if (cpu_is_at91rm9200())
> > + at91_pm_data.memctrl = AT91_MEMCTRL_SDRAMC;
> > +
> > + if (of_machine_is_compatible("atmel,at91rm9200")) {
> > + /*
> > + * AT91RM9200 SDRAM low-power mode cannot be used with
> > + * self-refresh.
> > + */
> > at91_ramc_write(0, AT91RM9200_SDRAMC_LPR, 0);
> > -
> > +
> > + at91_pm_data.uhp_udp_mask = AT91RM9200_PMC_UHP |
> > + AT91RM9200_PMC_UDP;
> > + at91_pm_data.memctrl = AT91_MEMCTRL_MC;
> > + } else if (of_machine_is_compatible("atmel,at91sam9260") ||
> > + of_machine_is_compatible("atmel,at91sam9g20") ||
> > + of_machine_is_compatible("atmel,at91sam9261") ||
> > + of_machine_is_compatible("atmel,at91sam9g10") ||
> > + of_machine_is_compatible("atmel,at91sam9263")) {
> nack here
>
> you switch for runtime information from the SOC register store in ram to DT
>
> DT is great but I do prefer to rely on the SoC register here as the whole was
> also to check that the is correct
Well, cpu_is_xxx macros are defined in a mach specific header, and we're
currently trying to enable multi platform support.
>
> wihich is way slower
Hmm, this SoC detection has been move from the suspend path (where, as
you stated, speed is a real concern) to the pm init function (which is
only called once at startup), and I doubt the boot time penalty will
even be noticeable...
Best Regards,
Boris
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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