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

[Marek Vasut]

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.

> 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.