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

[Masahiro Yamada]

On Thu, Jan 9, 2020 at 11:48 PM Marek Vasut <marex at denx.de> wrote:
>
> On 1/9/20 1:11 PM, Masahiro Yamada wrote:
> > On Thu, Jan 9, 2020 at 8:16 PM Marek Vasut <marex at 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 at 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 at denx.de>
> >>>> Cc: Masahiro Yamada <yamada.masahiro at 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 Denali NAND patches for Linux are currently stuck on your review too.

Huh?

Which patch in Linux is stuck on my review?



> > 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.
>
> Once the Linux patches are upstream, we can just reset the NAND
> controller without problems. And that's the right thing to do, sometimes
> you don't want NAND to be available in Linux, and then it should be kept
> in reset.


The NAND reset in Linux will be available in the future version
(if my patch is applied).

The stable kernels are maintained in 6 years.

https://www.kernel.org/category/releases.html

The EOF of Linux 5.4 is set at 2021.12, but
following the recent rules, it will be extended
to 2026 or so.



-- 
Best Regards
Masahiro Yamada