sunxi: spl: Fix H616 clock initialization

It turns out that there is a magic bit in PRCM region which seemingly
makes PLLs work if it's enabled. Sadly, there is no documentation what
it does exactly, so we'll just mimick BSP boot0 behaviour and enable it
before any clock is set up.

Fixes: b18bd53d6cde ("sunxi: introduce support for H616 clocks")
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
---
 arch/arm/mach-sunxi/clock_sun50i_h6.c | 6 ++++++
 1 file changed, 6 insertions(+)

On Sun, 31 Jan 2021 21:25:39 +0100
Jernej Skrabec <jernej.skrabec@siol.net> wrote:

Hi Jernej,

> It turns out that there is a magic bit in PRCM region which seemingly
> makes PLLs work if it's enabled. Sadly, there is no documentation what
> it does exactly, so we'll just mimick BSP boot0 behaviour and enable it
> before any clock is set up.

Good job of figuring this out!

> Fixes: b18bd53d6cde ("sunxi: introduce support for H616 clocks")
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> ---
>  arch/arm/mach-sunxi/clock_sun50i_h6.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm/mach-sunxi/clock_sun50i_h6.c b/arch/arm/mach-sunxi/clock_sun50i_h6.c
> index 06d84eb158d7..68c8e7f2afbe 100644
> --- a/arch/arm/mach-sunxi/clock_sun50i_h6.c
> +++ b/arch/arm/mach-sunxi/clock_sun50i_h6.c
> @@ -9,6 +9,12 @@ void clock_init_safe(void)
>  {
>  	struct sunxi_ccm_reg *const ccm =
>  		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
> +
> +#ifdef CONFIG_MACH_SUN50I_H616

Can you change this to: if (IS_ENABLED())?

> +	/* this seems to enable PLLs */

Out of curiosity, what makes you think it's PLL related? At least the
PERIPH0 and CPU PLLs seem to work without it?

Cheers,
Andre

> +	setbits_le32(SUNXI_PRCM_BASE + 0x250, 0x10);
> +#endif
> +
>  	clock_set_pll1(408000000);
>  
>  	writel(CCM_PLL6_DEFAULT, &ccm->pll6_cfg);

Dne ponedeljek, 01. februar 2021 ob 01:46:22 CET je Andre Przywara napisal(a):
> On Sun, 31 Jan 2021 21:25:39 +0100
> Jernej Skrabec <jernej.skrabec@siol.net> wrote:
> 
> Hi Jernej,
> 
> > It turns out that there is a magic bit in PRCM region which seemingly
> > makes PLLs work if it's enabled. Sadly, there is no documentation what
> > it does exactly, so we'll just mimick BSP boot0 behaviour and enable it
> > before any clock is set up.
> 
> Good job of figuring this out!
> 
> > Fixes: b18bd53d6cde ("sunxi: introduce support for H616 clocks")
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> > 
> >  arch/arm/mach-sunxi/clock_sun50i_h6.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/arch/arm/mach-sunxi/clock_sun50i_h6.c
> > b/arch/arm/mach-sunxi/clock_sun50i_h6.c index 06d84eb158d7..68c8e7f2afbe
> > 100644
> > --- a/arch/arm/mach-sunxi/clock_sun50i_h6.c
> > +++ b/arch/arm/mach-sunxi/clock_sun50i_h6.c
> > @@ -9,6 +9,12 @@ void clock_init_safe(void)
> > 
> >  {
> >  
> >  	struct sunxi_ccm_reg *const ccm =
> >  	
> >  		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
> > 
> > +
> > +#ifdef CONFIG_MACH_SUN50I_H616
> 
> Can you change this to: if (IS_ENABLED())?

ok.

> 
> > +	/* this seems to enable PLLs */
> 
> Out of curiosity, what makes you think it's PLL related? At least the
> PERIPH0 and CPU PLLs seem to work without it?

Because I was able to configure TCON TOP -> TCON TV0 -> HDMI chain just fine, 
but nothing would be shown on screen, not even test patterns from TCON. HDMI 
itself worked ok (EDID could be read). I noticed that vblank interrupts were 
not genereted. This and no image is consisted with disabling bus clock to TCON 
and HDMI. I checked several times that clock configuration matches to that in 
BSP... I also moved both to another PLL without success. Also, this bit was 
discovered in function, which does clock initialization.

PLL cpu is always special case, otherwise nothing would work at boot. I have 
no real explanation for PLL periph...

Best regards,
Jernej

> 
> Cheers,
> Andre
> 
> > +	setbits_le32(SUNXI_PRCM_BASE + 0x250, 0x10);
> > +#endif
> > +
> > 
> >  	clock_set_pll1(408000000);
> >  	
> >  	writel(CCM_PLL6_DEFAULT, &ccm->pll6_cfg);