Re: [PATCH/RFC 3/2] OMAP: PM noop: implement context loss count for non-omap_devices

Paul Walmsley
2010-12-15T03:39:56Z

Hi

a few more minor comments

On Thu, 9 Dec 2010, Kevin Hilman wrote:

> For devices which have not (yet) been converted to use omap_device,
> implement the context loss counter using the "brutal method" as
> originally proposed by Paul Walmsley[1].
>
> The dummy context loss counter is incremented every time it is
> checked, but only when off-mode is enabled. When off-mode is
> disabled, the dummy counter stops incrementing.
>
> Tested on 36xx/Zoom3 using MMC driver, which is currently the
> only in-tree user of this API.
>
> This patch should be reverted after all devices are converted to using
> omap_device.
>
> [1] http://marc.info/?l=linux-omap&m=129176260000626&w=2
>
> Cc: Paul Walmsley <paul@pwsan.com>
> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
> ---
> arch/arm/mach-omap2/pm-debug.c | 2 ++
> arch/arm/plat-omap/include/plat/omap-pm.h | 1 +
> arch/arm/plat-omap/omap-pm-noop.c | 19 ++++++++++++++++++-
> 3 files changed, 21 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/pm-debug.c b/arch/arm/mach-omap2/pm-debug.c
> index e535082..af66acb 100644
> --- a/arch/arm/mach-omap2/pm-debug.c
> +++ b/arch/arm/mach-omap2/pm-debug.c
> @@ -32,6 +32,7 @@
> #include "powerdomain.h"
> #include "clockdomain.h"
> #include <plat/dmtimer.h>
> +#include <plat/omap-pm.h>
>
> #include "cm2xxx_3xxx.h"
> #include "prm2xxx_3xxx.h"
> @@ -581,6 +582,7 @@ static int option_set(void *data, u64 val)
> *option = val;
>
> if (option == &enable_off_mode) {
> + omap_pm_enable_off_mode(val ? true : false);
> if (cpu_is_omap34xx())
> omap3_pm_off_mode_enable(val);
> }
> diff --git a/arch/arm/plat-omap/include/plat/omap-pm.h b/arch/arm/plat-omap/include/plat/omap-pm.h
> index 9870b4f..cfa5e44 100644
> --- a/arch/arm/plat-omap/include/plat/omap-pm.h
> +++ b/arch/arm/plat-omap/include/plat/omap-pm.h
> @@ -372,5 +372,6 @@ unsigned long omap_pm_cpu_get_freq(void);
> */
> int omap_pm_get_dev_context_loss_count(struct device *dev);
>
> +void omap_pm_enable_off_mode(bool enable);
>
> #endif
> diff --git a/arch/arm/plat-omap/omap-pm-noop.c b/arch/arm/plat-omap/omap-pm-noop.c
> index 5a58f97..32f2818 100644
> --- a/arch/arm/plat-omap/omap-pm-noop.c
> +++ b/arch/arm/plat-omap/omap-pm-noop.c
> @@ -30,6 +30,9 @@ struct omap_opp *dsp_opps;
> struct omap_opp *mpu_opps;
> struct omap_opp *l3_opps;
>
> +static bool off_mode_enabled;
> +static u32 dummy_context_loss_counter;
> +
> /*
> * Device-driver-originated constraints (via board-*.c files)
> */
> @@ -287,6 +290,10 @@ unsigned long omap_pm_cpu_get_freq(void)
> /*
> * Device context loss tracking
> */

Please add some basic kerneldoc here -- maybe just document that it's
meant to be called from the core OMAP PM or PM debug code whenever
off-mode is enabled or disabled...

> +void omap_pm_enable_off_mode(bool enable)
> +{
> + off_mode_enabled = enable;
> +}

Personal preference: please split this into two functions,
omap_pm_{enable,disable}_off_mode(void). That way, when I read it in
other code, I don't have to try to remember what the argument means :-)

> int omap_pm_get_dev_context_loss_count(struct device *dev)
> {
> @@ -298,7 +305,17 @@ int omap_pm_get_dev_context_loss_count(struct device *dev)
> return -EINVAL;
> };
>
> - count = omap_device_get_context_loss_count(pdev);
> + if (dev->parent == &omap_device_parent) {
> + count = omap_device_get_context_loss_count(pdev);
> + } else {
> + WARN_ONCE(off_mode_enabled, "using dummy context loss counter, "
> + "device %s should be converted to omap_device.",
> + __func__, dev_name(dev));
> + if (off_mode_enabled)
> + dummy_context_loss_counter++;
> + count = dummy_context_loss_counter;
> + }
> +

This part looks fine to me, thanks for working on this stuff. Once you
fix the arithmetic rollover stuff, I think it will be good for 2.6.38.

- Paul