[U-Boot] [PATCH v1 1/4] arm: socfpga: imply SPL config instead of select

[Marek Vasut]

On 1/14/19 9:30 PM, Simon Goldschmidt wrote:
> On Mon, Jan 14, 2019 at 9:23 PM Marek Vasut <marex at denx.de> wrote:
>>
>> On 1/14/19 9:12 PM, Simon Goldschmidt wrote:
>>> Am 14.01.2019 um 21:01 schrieb Marek Vasut:
>>>> On 1/14/19 8:43 PM, Simon Goldschmidt wrote:
>>>>> Am 14.01.2019 um 20:33 schrieb Marek Vasut:
>>>>>> On 1/14/19 7:58 PM, Simon Goldschmidt wrote:
>>>>>>> Am 14.01.2019 um 19:31 schrieb Marek Vasut:
>>>>>>>> On 1/14/19 5:05 PM, Simon Goldschmidt wrote:
>>>>>>>>> Hi Dinh,
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>>> Am 14.01.2019 um 16:58 schrieb Dinh Nguyen:
>>>>>>>>>> Hi Simon,
>>>>>>>>>>
>>>>>>>>>> On 1/14/19 9:50 AM, Simon Goldschmidt wrote:
>>>>>>>>>>> Am 11.01.2019 um 23:02 schrieb Marek Vasut:
>>>>>>>>>>>> On 1/11/19 9:39 PM, Simon Goldschmidt wrote:
>>>>>>>>>>>>> Am 07.01.2019 um 23:53 schrieb Marek Vasut:
>>>>>>>>>>>>>> On 1/7/19 10:14 PM, Simon Goldschmidt wrote:
>>>>>>>>>>>>>>> In order to build a smaller SPL, let's imply SPL_DM_RESET and
>>>>>>>>>>>>>>> SPL_WATCHDOG_SUPPORT instead of selecting them, so they can be
>>>>>>>>>>>>>>> disabled
>>>>>>>>>>>>>>> via defconfig.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> This also seems to be required to use OF_PLATDATA, as the
>>>>>>>>>>>>>>> reset
>>>>>>>>>>>>>>> drivers
>>>>>>>>>>>>>>> don't seem to work with it.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> How do you un-reset IP blocks if you disable the reset
>>>>>>>>>>>>>> controller ?
>>>>>>>>>>>>>
>>>>>>>>>>>>> I found that out just now: there's the function
>>>>>>>>>>>>> 'reset_deassert_peripherals_handoff()' in spl_gen5.c that should
>>>>>>>>>>>>> "De-assert reset for peripherals and bridges based on handoff".
>>>>>>>>>>>>> However,
>>>>>>>>>>>>> at least for Gen5, it just writes a 0 to rstmgr->permodrst. By
>>>>>>>>>>>>> doing
>>>>>>>>>>>>> that, it enables *ALL* peripherals on the SoC (except for
>>>>>>>>>>>>> some DMA
>>>>>>>>>>>>> channels that aren't really used) :-)
>>>>>>>>>>>>>
>>>>>>>>>>>>> I guess that needs some cleaning up as well ;-)
>>>>>>>>>>>>
>>>>>>>>>>>> Yes
>>>>>>>>>>>>
>>>>>>>>>>>>> I think the proper thing to do here would be to remove this
>>>>>>>>>>>>> function and
>>>>>>>>>>>>> convert all drivers to provide appropriate 'resets'
>>>>>>>>>>>>> properties in
>>>>>>>>>>>>> the
>>>>>>>>>>>>> dts?
>>>>>>>>>>>>
>>>>>>>>>>>> Indeed
>>>>>>>>>>>
>>>>>>>>>>> So I just did that and it works nice for SPL and U-Boot: By adding
>>>>>>>>>>> some
>>>>>>>>>>> "resets" properties the the main dtsi and adding reset bulk
>>>>>>>>>>> code to
>>>>>>>>>>> the
>>>>>>>>>>> cadence_qspi, denali_dt nand and drivers, I can nearly remove the
>>>>>>>>>>> reset
>>>>>>>>>>> code from arch/mach_socfpga.
>>>>>>>>>>>
>>>>>>>>>>> The problem would be that now Linux cannot use peripherals that
>>>>>>>>>>> aren't
>>>>>>>>>>> enabled by U-Boot because it relies on them being enabled. How are
>>>>>>>>>>> such
>>>>>>>>>>> dependencies solved? Because even if I would add reset support in
>>>>>>>>>>> the
>>>>>>>>>>> corresponding Linux drivers, we probably could not bootolder
>>>>>>>>>>> Kernels
>>>>>>>>>>> (e.g. the Debian 9 kernel - v4.9.x) with a new U-Boot...
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I added an early reset driver for SoCFPGA that should take care of
>>>>>>>>>> this.
>>>>>>>>>> The patch is in v5.0-rc2[1].
>>>>>>>>>
>>>>>>>>> OK, it's good to know that this work is already done, I haven't
>>>>>>>>> monitored this close enough.
>>>>>>>>
>>>>>>>> We had the same problem with A10, indeed.
>>>>>>>>
>>>>>>>>> But am I correct that my above problem remains even in v5.0 as
>>>>>>>>> not all
>>>>>>>>> peripherals in socfpga.dtsi have a "resets" property set (e.g.
>>>>>>>>> mmc and
>>>>>>>>> qspi) and would thuse not be taken out of reset by Linux?
>>>>>>>>>
>>>>>>>>> Plus: should U-Boot work with older Linux kernels? Because if so, we
>>>>>>>>> need fallback code in U-Boot to unreset peripherals when running
>>>>>>>>> with an
>>>>>>>>> older kernel...
>>>>>>>>
>>>>>>>> Yes, it'd break old broken kernels . The real question is, do we
>>>>>>>> care ?
>>>>>>>
>>>>>>> Ok, so that at leat shows me I'm going into the right direction :-)
>>>>>>>
>>>>>>> There are some problems though:
>>>>>>> - I do care (we're running 4.9 currently) *g*
>>>>>>> - people running an RT kernel will care for a while (until the next
>>>>>>> stable RT after fixing this will be released)
>>>>>>> - we would currently be breaking *all* kernels, since no kernel should
>>>>>>> yet be able to deassert reset for mmc and qspi (unless this is already
>>>>>>> done by U-Boot)...
>>>>>>>
>>>>>>> So would it be OK to add a Kconfig option to U-Boot to keep the
>>>>>>> current
>>>>>>> behaviour (for old broken kernels like you said) until that code is
>>>>>>> spread widely enough? Or is that a no-go?
>>>>>>
>>>>>> Would be nice to be able to tweak the reset driver behavior at runtime,
>>>>>> to unreset things before booting the kernel if the user desires so.
>>>>>
>>>>> Instead of tweaking the reset driver, we could just add a command that
>>>>> does that 'rstmgr->permodrst = 0;' thing my patch would remove.
>>>>
>>>> I don't want a new custom command.
>>>>
>>>>> Since noone has complained so far, I think writing 0 should be OK here.
>>>>> I don't think it would make too much sense to use the reset handoff
>>>>> defines from Quartus output for such a command. I think the way Quartus
>>>>> does this is strange anyway...
>>>>>
>>>>> The question is if defconfigs should be able to use this to
>>>>> automatically build a U-Boot config for older kernels. If so, we'd still
>>>>> need a Kconfig option?
>>>>
>>>> I'd much rather have this runtime configurable.
>>>
>>> Then I'm afraid I don't know what you mean by "runtime configurable".
>>> What should be the configuration source that is evaluated at runtime?
>>
>> I wonder ... maybe an environment variable with a U_BOOT_ENV_CALLBACK()
>> hook ?
> 
> But when doing it like that, I'd still have to modify the U-Boot
> sources to build a version of U-Boot that could successfully boot a
> 4.9 kernel.
> I wanted to be able to do that without changing the sources, that's
> why I would have added a Kconfig option...

If you have an environment variable which allows you to indicate that
your kernel is broken/old, you can set it and boot.

>>>>> Thinking further about cleanup: I guess the clock driver is not that
>>>>> hard to implement, either. The only thing that's driving me mad is
>>>>> pinmux. Is there any chance to get more info from Intel to write this
>>>>> properly so we can get rid of that iocsr scanchain defines?
>>>>
>>>> Clock driver should be easy, yes. Pinmux, I don't know, maybe project
>>>> chibi has some information (the cyclone I documentation project).
>>>
>>> Interesing, I didn't know that project. The only thing I found is a repo
>>> on github. But it seems like that one only contains FPGA-related stuff,
>>> nothing about the HPS side...
>>
>> My understanding is that the IOCSR ring is on the FPGA side and it's
>> exactly the same as pinmux configuration for the FPGA IO, but I might be
>> wrong.
> 
> Hmm, I really don't know. Has anyone ever tried asking Intel for this?
> Is it a known fact that they won't give away such specs?

Dinh is on CC :)

-- 
Best regards,
Marek Vasut