[PATCH 3/3] mtd: rawnand: denali: Do not reset the block on SoCFPGA

From: Masahiro Yamada <masahiroy@kernel.org>
To: u-boot@lists.denx.de
Subject: [PATCH 3/3] mtd: rawnand: denali: Do not reset the block on SoCFPGA
Date: Thu, 9 Jan 2020 21:11:27 +0900	[thread overview]
Message-ID: <CAK7LNAQvXfZHEmtGmEHU4w14mVtY=h0PpFvLDunhxxSCM5o4PA@mail.gmail.com> (raw)
In-Reply-To: <fb4cecd5-e752-ba00-2d71-da0a1faa1ba7@denx.de>

On Thu, Jan 9, 2020 at 8:16 PM Marek Vasut <marex@denx.de> wrote:
>
> On 1/9/20 12:04 PM, Masahiro Yamada wrote:
> > On Thu, Jan 9, 2020 at 7:08 PM Marek Vasut <marex@denx.de> wrote:
> >>
> >> Legacy kernel versions for SoCFPGA may not implement proper reset
> >> handling. Apply the same approach as SoCFPGA reset driver, check
> >> environment variable "socfpga_legacy_reset_compat", and if it is
> >> set, do not reset the IP before booting Linux. This way, even the
> >> older kernel versions can be booted by up to date U-Boot.
> >>
> >> Signed-off-by: Marek Vasut <marex@denx.de>
> >> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> >> ---
> >>  drivers/mtd/nand/raw/denali_dt.c | 12 ++++++++++++
> >>  1 file changed, 12 insertions(+)
> >>
> >> diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
> >> index 2c9e249ab6..d35f2a3543 100644
> >> --- a/drivers/mtd/nand/raw/denali_dt.c
> >> +++ b/drivers/mtd/nand/raw/denali_dt.c
> >> @@ -148,6 +148,18 @@ static int denali_dt_remove(struct udevice *dev)
> >>  {
> >>         struct denali_nand_info *denali = dev_get_priv(dev);
> >>
> >> +#if CONFIG_IS_ENABLED(ARCH_SOCFPGA)
> >> +       /*
> >> +        * Legacy kernel versions do not implement proper reset handling on
> >> +        * SoCFPGA. To let those older kernel versions work, reuse the same
> >> +        * approach as the SoCFPGA reset driver does -- check environment
> >> +        * variable socfpga_legacy_reset_compat and avoid resetting the IP
> >> +        * before booting the kernel if it is set to 1.
> >> +        */
> >> +       if (env_get_ulong("socfpga_legacy_reset_compat", 10, 0))
> >> +               return 0;
> >> +#endif
> >> +
> >>         return reset_release_bulk(&denali->resets);
> >>  }
> >
> >
> > Why don't you simply remove reset_release_bulk() ?
>
> Because once mainline has proper reset handling, this can be used only
> for legacy kernel versions.

I am suffering for the same problem for the uniphier platform.

The reset driver support for Linux will never be back-ported.
So, it will continue to be a problem for Linux v4.19, v5.4, etc.

reset_release_bulk() should go away.

-- 
Best Regards
Masahiro Yamada