Hi
On Tue, 23 Jun 2015, Roger Quadros wrote:
> For some hwmods (e.g. DCAN on DRA7) we need the possibility to
> disable HW_AUTO for the clockdomain while the module is active.
>
> To achieve this there needs to be a refcounting mechanism to
> indicate whether any module in the clockdomain has requested
> to disable HW_AUTO. We keep track of this in 'noidlecount'.
>
> Hwmod code must use clkdm_hwmod_prevent_hwauto() to prevent
> HW_AUTO of the clockdomain in the future clkdm_hwmod_hwauto() calls.
>
> It must use clkdm_hwmod_allow_hwauto() to allow HW_AUTO in
> the future clkdm_hwmod_hwauto() calls.
>
> Hwmod code must use clkdm_hwmod_allow_hwauto() whenever it needs
> to request HW_AUTO of any clockdomain. (Typically after it has
> enabled the module).
How about just modifying clkdm_{allow,deny}_idle*() to do the
idle-block-counting? The default state would be to allow idle, assuming
that the clockdomain flags support that state, and then clkdm_deny_idle*()
would increment the idle-blocking count, clkdm_allow_idle*() would
decrement it. Then on the 0 -> 1 or 1 -> 0 transitions, the hardware
would be reprogrammed appropiately.
Anyway, seems like that would avoid races with any
clkdm_{allow,deny}_idle*() users.
A few other comments below:
>
> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> ---
> arch/arm/mach-omap2/clockdomain.c | 71 +++++++++++++++++++++++++++++++++++++++
> arch/arm/mach-omap2/clockdomain.h | 5 +++
> 2 files changed, 76 insertions(+)
>
> diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c
> index 2da3b5e..a7190d2 100644
> --- a/arch/arm/mach-omap2/clockdomain.c
> +++ b/arch/arm/mach-omap2/clockdomain.c
> @@ -1212,6 +1212,77 @@ ccd_exit:
> return 0;
> }
>
> +/*
> + * prevent future hwauto for this clkdm. If clkdm->usecount becomes hwauto isn't prevented.
> + * It will only prevnt future hwauto but not bring it out of hwauto.
> + */
If you modify clkdm_{allow,deny}_idle*(), this shouldn't be a major issue
- but all of the function comments should be fixed so that they are
understandable and follow kernel-doc-nano specs.
> +int clkdm_hwmod_prevent_hwauto(struct clockdomain *clkdm, struct omap_hwmod *oh)
> +{
> + /* The clkdm attribute does not exist yet prior OMAP4 */
> + if (cpu_is_omap24xx() || cpu_is_omap34xx())
> + return 0;
> +
> + if (!clkdm || !oh || !arch_clkdm || !arch_clkdm->clkdm_clk_disable)
> + return -EINVAL;
> +
> +
> + pwrdm_lock(clkdm->pwrdm.ptr);
> + clkdm->noidlecount++;
> + pwrdm_unlock(clkdm->pwrdm.ptr);
> +
> + return 0;
> +}
> +
> +/*
> + * allow future hwauto for this clkdm
> + * It won't put clkdm into hwauto. use clkdm_hwmod_hwauto() for that.
> + */
> +int clkdm_hwmod_allow_hwauto(struct clockdomain *clkdm, struct omap_hwmod *oh)
> +{
> + /* The clkdm attribute does not exist yet prior OMAP4 */
> + if (cpu_is_omap24xx() || cpu_is_omap34xx())
> + return 0;
> +
> + if (!clkdm || !oh || !arch_clkdm || !arch_clkdm->clkdm_clk_disable)
> + return -EINVAL;
> +
> +
> + pwrdm_lock(clkdm->pwrdm.ptr);
> +
> + if (clkdm->noidlecount == 0) {
> + pwrdm_unlock(clkdm->pwrdm.ptr);
> + WARN_ON(1); /* underflow */
> + return -ERANGE;
> + }
> +
> + clkdm->noidlecount--;
> + pwrdm_unlock(clkdm->pwrdm.ptr);
> +
> + return 0;
> +}
> +
> +/*
> + * put clkdm in hwauto if we can. checks noidlecount to see if we can.
> + */
> +int clkdm_hwmod_hwauto(struct clockdomain *clkdm, struct omap_hwmod *oh)
> +{
> + /* The clkdm attribute does not exist yet prior OMAP4 */
> + if (cpu_is_omap24xx() || cpu_is_omap34xx())
> + return 0;
> +
> + if (!clkdm || !oh || !arch_clkdm || !arch_clkdm->clkdm_clk_disable)
> + return -EINVAL;
> +
> +
> + pwrdm_lock(clkdm->pwrdm.ptr);
> + if (clkdm->noidlecount == 0)
> + clkdm_allow_idle_nolock(clkdm);
> +
> + pwrdm_unlock(clkdm->pwrdm.ptr);
> +
> + return 0;
> +}
> +
> /**
> * clkdm_hwmod_enable - add an enabled downstream hwmod to this clkdm
> * @clkdm: struct clockdomain *
> diff --git a/arch/arm/mach-omap2/clockdomain.h b/arch/arm/mach-omap2/clockdomain.h
> index 77bab5f..8c491be 100644
> --- a/arch/arm/mach-omap2/clockdomain.h
> +++ b/arch/arm/mach-omap2/clockdomain.h
> @@ -114,6 +114,7 @@ struct omap_hwmod;
> * @wkdep_srcs: Clockdomains that can be told to wake this powerdomain up
> * @sleepdep_srcs: Clockdomains that can be told to keep this clkdm from inact
> * @usecount: Usecount tracking
> + * @noidlecount: Noidle count tracking. Domain won't be auto idled this is > 0.
> * @node: list_head to link all clockdomains together
> *
> * @prcm_partition should be a macro from mach-omap2/prcm44xx.h (OMAP4 only)
> @@ -138,6 +139,7 @@ struct clockdomain {
> struct clkdm_dep *wkdep_srcs;
> struct clkdm_dep *sleepdep_srcs;
> int usecount;
> + int noidlecount;
> struct list_head node;
> };
>
> @@ -211,6 +213,9 @@ int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk);
> int clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk);
> int clkdm_hwmod_enable(struct clockdomain *clkdm, struct omap_hwmod *oh);
> int clkdm_hwmod_disable(struct clockdomain *clkdm, struct omap_hwmod *oh);
> +int clkdm_hwmod_prevent_hwauto(struct clockdomain *clkdm, struct omap_hwmod *oh);
> +int clkdm_hwmod_allow_hwauto(struct clockdomain *clkdm, struct omap_hwmod *oh);
> +int clkdm_hwmod_hwauto(struct clockdomain *clkdm, struct omap_hwmod *oh);
>
> extern void __init omap242x_clockdomains_init(void);
> extern void __init omap243x_clockdomains_init(void);
> --
> 2.1.4
>
- Paul
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