Re: [PATCH 1/2] ARM: Rockchip: Handle rk3288/rk3288w revision

[Ezequiel Garcia <ezequiel@collabora.com>]

Hi Heiko,

On Wed, 2020-03-04 at 11:59 +0100, Heiko Stübner wrote:
> Hi,
> 
> Am Montag, 2. März 2020, 16:57:02 CET schrieb Mylène Josserand:
> > Determine which revision of rk3288 by checking the HDMI version.
> > According to the Rockchip BSP kernel, on rk3288w, the HDMI
> > revision equals 0x1A which is not the case for the rk3288 [1].
> > 
> > As these SOC have some differences, the new function
> > 'soc_is_rk3288w' will help us to know on which revision
> > we are.
> 
> what happened to just having a different compatible in the dts?
> Aka doing a 
> 
> rk3288w.dtsi with
> 
> #include "rk3288.dtsi"
> 
> &cru {
> 	compatible = "rockchip,rk3288w-cru";
> }
> 

I guess you have something like this in mind:

static void __init rk3288_clk_init(struct device_node *np)
{
        __rk3288_clk_init(np, RK3288_SOC_REV_RK3288W);
}
CLK_OF_DECLARE(rk3288_cru, "rockchip,rk3288-cru", rk3288_clk_init);

static void __init rk3288w_clk_init(struct device_node *np)
{
        __rk3288_clk_init(np, RK3288_SOC_REV_RK3288);
}
CLK_OF_DECLARE(rk3288_cru, "rockchip,rk3288w-cru", rk3288w_clk_init);

And the rest is mostly untouched, except the revision is
no longer queried and is now passed by the DT?

This would be cleaner for the kernel, with the obvious
drawback being that you now have to maintain
another DTS.

This could be an inconvenience. I believe
RK3288W is meant as a direct replacement for RK3288,
so folks building products would expect to just use
RK3288W, and not really bother with passing a
different DTS or what not.

> I somehow don't expect boards to just switch between soc variants
> on the fly.
> 

While I agree they are nasty, quirks like this
are not uncommon.

> Also, doing things in mach-rockchip is not very future-proof:
> 

There is actually no reason to keep this in mach-rockchip, right?

The quirk could be placed in other places. For instance,
directly in the clock driver.

Thanks for reviewing!
Ezequiel

> (1) having random soc-specific APIs spanning the kernel feels wrong,
>     especially as at some point it might not be contained to our own special
>     drivers like the cru. I cannot really see people being enthusiastic if
>     something like this would be needed in say the core Analogix-DP bridge ;-)
> (2) I guess the rk3288w will not be the last soc doing this and on arm64 you
>     can't do it that way, as there is no mach-rockchip there
> 
> So my personal preference would really would be just a specific compatible
> for affected ip blocks.
> 
> Heiko
> 
> > [1]:https://github.com/rockchip-linux/u-boot/blob/f992fe3334aa5090acb448261982628b5a3d37a5/arch/arm/include/asm/arch-rockchip/cpu.h#L30..L34
> > 
> > Signed-off-by: Mylène Josserand <mylene.josserand@collabora.com>
> > ---
> >  arch/arm/mach-rockchip/rockchip.c | 45 +++++++++++++++++++++++++++++++
> >  include/soc/rockchip/revision.h   | 22 +++++++++++++++
> >  2 files changed, 67 insertions(+)
> >  create mode 100644 include/soc/rockchip/revision.h
> > 
> > diff --git a/arch/arm/mach-rockchip/rockchip.c b/arch/arm/mach-rockchip/rockchip.c
> > index f9797a2b5d0d..b907ba390093 100644
> > --- a/arch/arm/mach-rockchip/rockchip.c
> > +++ b/arch/arm/mach-rockchip/rockchip.c
> > @@ -9,12 +9,14 @@
> >  #include <linux/kernel.h>
> >  #include <linux/init.h>
> >  #include <linux/io.h>
> > +#include <linux/of_address.h>
> >  #include <linux/of_platform.h>
> >  #include <linux/irqchip.h>
> >  #include <linux/clk-provider.h>
> >  #include <linux/clocksource.h>
> >  #include <linux/mfd/syscon.h>
> >  #include <linux/regmap.h>
> > +#include <soc/rockchip/revision.h>
> >  #include <asm/mach/arch.h>
> >  #include <asm/mach/map.h>
> >  #include <asm/hardware/cache-l2x0.h>
> > @@ -22,6 +24,49 @@
> >  #include "pm.h"
> >  
> >  #define RK3288_TIMER6_7_PHYS 0xff810000
> > +#define RK3288_HDMI_REV_REG	0x04
> > +#define RK3288W_HDMI_REV	0x1A
> > +
> > +static const struct of_device_id rk3288_dt_hdmi_match[] __initconst = {
> > +	{ .compatible = "rockchip,rk3288-dw-hdmi" },
> > +	{ }
> > +};
> > +
> > +int rk3288_get_revision(void)
> > +{
> > +	static int revision = RK3288_SOC_REV_UNKNOWN;
> > +	struct device_node *dn;
> > +	void __iomem *hdmi_base;
> > +
> > +	if (revision != RK3288_SOC_REV_UNKNOWN)
> > +		return revision;
> > +
> > +	dn = of_find_matching_node(NULL, rk3288_dt_hdmi_match);
> > +	if (!dn) {
> > +		pr_err("%s: Couldn't find HDMI node\n", __func__);
> > +		return -EINVAL;
> > +	}
> > +
> > +	hdmi_base = of_iomap(dn, 0);
> > +	of_node_put(dn);
> > +
> > +	if (!hdmi_base) {
> > +		pr_err("%s: Couldn't map %pOF regs\n", __func__,
> > +		       hdmi_base);
> > +		return -ENXIO;
> > +	}
> > +
> > +	if (readl_relaxed(hdmi_base + RK3288_HDMI_REV_REG) ==
> > +	    RK3288W_HDMI_REV)
> > +		revision = RK3288_SOC_REV_RK3288W;
> > +	else
> > +		revision = RK3288_SOC_REV_RK3288;
> > +
> > +	iounmap(hdmi_base);
> > +
> > +	return revision;
> > +}
> > +EXPORT_SYMBOL(rk3288_get_revision);
> >  
> >  static void __init rockchip_timer_init(void)
> >  {
> > diff --git a/include/soc/rockchip/revision.h b/include/soc/rockchip/revision.h
> > new file mode 100644
> > index 000000000000..226419c60af0
> > --- /dev/null
> > +++ b/include/soc/rockchip/revision.h
> > @@ -0,0 +1,22 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright 2020 Collabora
> > + */
> > +
> > +#ifndef __SOC_ROCKCHIP_REVISION_H__
> > +#define __SOC_ROCKCHIP_REVISION_H__
> > +
> > +enum rk3288_soc_revision {
> > +	RK3288_SOC_REV_UNKNOWN,
> > +	RK3288_SOC_REV_RK3288,
> > +	RK3288_SOC_REV_RK3288W,
> > +};
> > +
> > +int rk3288_get_revision(void);
> > +
> > +static inline bool soc_is_rk3288w(void)
> > +{
> > +	return rk3288_get_revision() == RK3288_SOC_REV_RK3288W;
> > +}
> > +
> > +#endif /* __SOC_ROCKCHIP_REVISION_H__ */
> > 
> 
> 
> 
> 



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