linux-kernel - Re: set rockchip-specific uboot bootmode flags on reboot (was: [PATCH] ARM: rockchip: add reboot notifier)

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Date:	Wed, 9 Sep 2015 12:05:37 -0600
From:	Simon Glass <sjg@...omium.org>
To:	Heiko Stübner <heiko@...ech.de>
Cc:	Andy Yan <andy.yan@...k-chips.com>,
	linux-rockchip@...ts.infradead.org,
	lk <linux-kernel@...r.kernel.org>,
	lak <linux-arm-kernel@...ts.infradead.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Olof Johansson <olof@...om.net>, khilman@...aro.org,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: set rockchip-specific uboot bootmode flags on reboot (was:
 [PATCH] ARM: rockchip: add reboot notifier)

Hi,

On 8 September 2015 at 16:46, Heiko Stübner <heiko@...ech.de> wrote:
>
> Hi Andy,
>
> Am Dienstag, 8. September 2015, 20:43:07 schrieb Andy Yan:
> > rockchip platform have a protocol to pass the the kernel
> > reboot mode to bootloader by some special registers when
> > system reboot.By this way the bootloader can take different
> > action according to the different kernel reboot mode, for
> > example, command "reboot loader" will reboot the board to
> > rockusb mode, this is a very convenient way to get the board
> > to download mode.
> >
> > Signed-off-by: Andy Yan <andy.yan@...k-chips.com>
>
> [...]
>
> > @@ -0,0 +1,22 @@
> > +#ifndef __MACH_ROCKCHIP_LOADER_H
> > +#define __MACH_ROCKCHIP_LOADER_H
> > +
> > +/*high 24 bits is tag, low 8 bits is type*/
> > +#define SYS_LOADER_REBOOT_FLAG   0x5242C300
> > +
> > +enum {
> > +     BOOT_NORMAL = 0, /* normal boot */
> > +     BOOT_LOADER,     /* enter loader rockusb mode */
> > +     BOOT_MASKROM,    /* enter maskrom rockusb mode (not support now) */
> > +     BOOT_RECOVER,    /* enter recover */
> > +     BOOT_NORECOVER,  /* do not enter recover */
> > +     BOOT_SECONDOS,   /* boot second OS (not support now)*/
> > +     BOOT_WIPEDATA,   /* enter recover and wipe data. */
> > +     BOOT_WIPEALL,    /* enter recover and wipe all data. */
> > +     BOOT_CHECKIMG,   /* check firmware img with backup part*/
> > +     BOOT_FASTBOOT,   /* enter fast boot mode */
> > +     BOOT_SECUREBOOT_DISABLE,
> > +     BOOT_CHARGING,   /* enter charge mode */
> > +     BOOT_MAX         /* MAX VALID BOOT TYPE.*/
> > +};
> > +#endif
>
> These flags rely on code in the bootloader to actually handle the target
> action. Nowadays this is uboot, but still a rockchip-specific fork. And we're
> actively moving away from that, with the recent rk3288 addition to mainline
> uboot.
>
> So unless you convince uboot people that the _underlying special
> functionality_ behind these flags should be part of uboot, I don't think this
> is going to fly.
>
>
> In a way this is similar to gpu kernel code talking to proprietary userspace
> libs - these are also not eligible for the kernel. (meaning stuff like the
> mali kernel driver not being allowed).

I don't want to comment on what Linux does or does not want. But I can
see this sort of feature being useful for devs at least. So long as it
is defined in a way that is not Rockchip-specific (and the above enum
looks pretty reasonable on that front, I think it makes sense.

Of course it's a bit odd to target a downstream U-Boot with a Linux
feature. But hopefully Rockchip's U-Boot support and development will
move to mainline with time.

>
> [...]
>
> > +static int rockchip_reboot_notify(struct notifier_block *this,
> > +                               unsigned long mode, void *cmd)
> > +{
> > +     u32 flag;
> > +
> > +     rockchip_get_reboot_flag(cmd, &flag);
> > +     regmap_write(regmap, flag_reg, flag);
> > +
> > +     return NOTIFY_DONE;
> > +}
> > +
> > +static struct notifier_block rockchip_reboot_handler = {
> > +     .notifier_call = rockchip_reboot_notify,
> > +     .priority = 150,
> > +};
>
> the restart handlers are meant to really only restart the system, not to
> execute some actions before the restart happens.
>
> See https://lkml.org/lkml/2015/6/3/707 for a similar case.
>
>
> Heiko

Regards,
Simon
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