Re: [PATCH v3 8/8] OMAP2+: hwmod: Follow the recommended PRCM module enable sequence

[Kevin Hilman <khilman@ti.com>]

Benoit Cousson <b-cousson@ti.com> writes:

> From: Rajendra Nayak <rnayak@ti.com>
>
> On OMAP4, the PRCM recommended sequence for enabling
> a module after power-on-reset is:
> -1- Force clkdm to SW_WKUP
> -2- Enabling the clocks
> -3- Configure desired module mode to "enable" or "auto"
> -4- Wait for the desired module idle status to be FUNC
> -5- Program clkdm in HW_AUTO(if supported)
>
> This sequence applies to all older OMAPs' as well,
> however since they use autodeps, it makes sure that
> no clkdm is in IDLE, and hence not requiring a force
> SW_WKUP when a module is being enabled.

OK, I found the problem that prevents booting on OMAP3...

> OMAP4 does not need to support autodeps, because
> of the dyanamic dependency feature, wherein
> the HW takes care of waking up a clockdomain from
> idle and hence the module, whenever an interconnect
> access happens to the given module.
>
> Implementing the sequence for OMAP4 requires
> the clockdomain handling that is currently done in
> clock framework to be done as part of hwmod framework
> since the step -4- above to "Wait for the desired
> module idle status to be FUNC" is done as part of
> hwmod framework.
>
> Signed-off-by: Rajendra Nayak <rnayak@ti.com>
> [b-cousson@ti.com: Adapt it to the new clkdm hwmod attribute and API]
> Signed-off-by: Benoit Cousson <b-cousson@ti.com>
> Cc: Paul Walmsley <paul@pwsan.com>
> ---
>  arch/arm/mach-omap2/clock.c      |   17 +----------------
>  arch/arm/mach-omap2/omap_hwmod.c |   26 +++++++++++++++++++++++++-
>  2 files changed, 26 insertions(+), 17 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
> index 180299e..2828d29 100644
> --- a/arch/arm/mach-omap2/clock.c
> +++ b/arch/arm/mach-omap2/clock.c
> @@ -268,9 +268,6 @@ void omap2_clk_disable(struct clk *clk)
>  		clk->ops->disable(clk);
>  	}
>  
> -	if (clk->clkdm)
> -		clkdm_clk_disable(clk->clkdm, clk);
> -
>  	if (clk->parent)
>  		omap2_clk_disable(clk->parent);
>  }
> @@ -308,30 +305,18 @@ int omap2_clk_enable(struct clk *clk)
>  		}
>  	}
>  
> -	if (clk->clkdm) {
> -		ret = clkdm_clk_enable(clk->clkdm, clk);
> -		if (ret) {
> -			WARN(1, "clock: %s: could not enable clockdomain %s: "
> -			     "%d\n", clk->name, clk->clkdm->name, ret);
> -			goto oce_err2;
> -		}
> -	}
> -
>  	if (clk->ops && clk->ops->enable) {
>  		trace_clock_enable(clk->name, 1, smp_processor_id());
>  		ret = clk->ops->enable(clk);
>  		if (ret) {
>  			WARN(1, "clock: %s: could not enable: %d\n",
>  			     clk->name, ret);
> -			goto oce_err3;
> +			goto oce_err2;
>  		}
>  	}

The clkdm enable/disable in this part of the patch is still required on
OMAP2/3, since the clkdm is still attached to the clock and not to the
hwmod.

Just backing out the mach-omap2/clock.c changes from this patch allows
this series to boot fine on OMAP3.

Kevin