Re: [PATCH v2 2/2] soc: amlogic: ee-pwrc: ensure driver state maches HW state

[Neil Armstrong <narmstrong@baylibre.com>]

On 25/09/2019 23:35, Kevin Hilman wrote:
> From: Kevin Hilman <khilman@baylibre.com>
> 
> During init, ensure that the driver on/off state as well as clock and
> reset state matches the hardware state.  Do this by always calling the
> drivers 'on' function, and then callling the 'off' function if the
> HW state was initially detected as off.
> 
> Signed-off-by: Kevin Hilman <khilman@baylibre.com>
> ---
>  drivers/soc/amlogic/meson-ee-pwrc.c | 29 ++++++++---------------------
>  1 file changed, 8 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/soc/amlogic/meson-ee-pwrc.c b/drivers/soc/amlogic/meson-ee-pwrc.c
> index dcce8e694a07..2e8eee0dc166 100644
> --- a/drivers/soc/amlogic/meson-ee-pwrc.c
> +++ b/drivers/soc/amlogic/meson-ee-pwrc.c
> @@ -323,6 +323,8 @@ static int meson_ee_pwrc_init_domain(struct platform_device *pdev,
>  				     struct meson_ee_pwrc *pwrc,
>  				     struct meson_ee_pwrc_domain *dom)
>  {
> +	bool is_off;
> +
>  	dom->pwrc = pwrc;
>  	dom->num_rstc = dom->desc.reset_names_count;
>  	dom->num_clks = dom->desc.clk_names_count;
> @@ -356,27 +358,12 @@ static int meson_ee_pwrc_init_domain(struct platform_device *pdev,
>  	dom->base.power_on = meson_ee_pwrc_on;
>  	dom->base.power_off = meson_ee_pwrc_off;
>  
> -	/*
> -         * TOFIX: This is a special case for the VPU power domain, which can
> -	 * be enabled previously by the bootloader. In this case the VPU
> -         * pipeline may be functional but no driver maybe never attach
> -         * to this power domain, and if the domain is disabled it could
> -         * cause system errors. This is why the pm_domain_always_on_gov
> -         * is used here.
> -         * For the same reason, the clocks should be enabled in case
> -         * we need to power the domain off, otherwise the internal clocks
> -         * prepare/enable counters won't be in sync.
> -         */
> -	if (dom->num_clks && dom->desc.is_off && !dom->desc.is_off(dom)) {
> -		int ret = clk_bulk_prepare_enable(dom->num_clks, dom->clks);
> -		if (ret)
> -			return ret;
> -
> -		pm_genpd_init(&dom->base, &pm_domain_always_on_gov, false);
> -	} else
> -		pm_genpd_init(&dom->base, NULL,
> -			      (dom->desc.is_off ?
> -			       dom->desc.is_off(dom) : true));
> +	/* Ensure that driver state matches HW state */
> +	is_off = dom->desc.is_off ? dom->desc.is_off(dom) : true;
> +	meson_ee_pwrc_on(&dom->base);
> +	if (is_off)
> +		meson_ee_pwrc_off(&dom->base);
> +	pm_genpd_init(&dom->base, NULL, is_off);
>  
>  	return 0;
>  }
> 

I don't see what you are trying to solve except simplifying the code.

And the case is more that "matching the clock state" here, the
pm_domain_always_on_gov was is a real case when booting from the Amlogic
U-boot.

The display power domain is complex and as been half solved by using
"simple-framebuffer" on gx and is missing on g12a/g12b/sm1.

For example, Debian installer runs without the modules, but will use
the EFIfb set by U-Boot, but in this precise case :
- the DRM driver isn't loaded
- we can't hook this power domain with EFIfb

When *not* in EFIfb, we use simple-framebuffer on GX, using this
power domain, but it hasn't been copied to G12A.

Personally I'll leave this code until we really tested and checked all
uses cases, not only on the sei510/sei610 using mainline u-boot.

Neil

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