[PATCH v4 06/12] arm: mvebu: clearfog: Add option for 2.5 Gbps SFP

[Baruch Siach <baruch@tkos.co.il>]

Hi Joel,

On Mon, Jan 27 2020, Joel Johnson wrote:
> On 2020-01-26 22:29, Baruch Siach wrote:
>> On Mon, Jan 27 2020, Joel Johnson wrote:
>>> While newer Linux kernels provide autoconfiguration of SFP, provide
>>> an option for setting in U-Boot Kconfig for use prior to booting.
>>>
>>> Signed-off-by: Joel Johnson <mrjoel@lixil.net>
>>>
>>> ---
>>>
>>> v2 changes:
>>>   - fixed help indentation
>>> v3 changes:
>>>   - none
>>> v4 changes:
>>>   - adjust static SerDes configuration at runtime instead of #ifdef
>>>
>>> ---
>>>  board/solidrun/clearfog/Kconfig    | 7 +++++++
>>>  board/solidrun/clearfog/clearfog.c | 3 +++
>>>  2 files changed, 10 insertions(+)
>>>
>>> diff --git a/board/solidrun/clearfog/Kconfig
>>> b/board/solidrun/clearfog/Kconfig
>>> index 936d5918f8..c910e17093 100644
>>> --- a/board/solidrun/clearfog/Kconfig
>>> +++ b/board/solidrun/clearfog/Kconfig
>>> @@ -15,4 +15,11 @@ config TARGET_CLEARFOG_BASE
>>>  	  detection via additional EEPROM hardware. This option enables
>>> selecting
>>>  	  the Base variant for older hardware revisions.
>>>
>>> +config CLEARFOG_SFP_25GB
>>> +	bool "Enable 2.5 Gbps mode for SFP"
>>> +	help
>>> +	  Set the SFP module connection to support 2.5 Gbps transfer speed for
>>> the
>>> +	  SGMII connection (requires a supporting SFP). By default, transfer
>>> speed
>>> +	  of 1.25 Gbps is used, suitable for a more common 1 Gbps SFP module.
>>> +
>>>  endmenu
>>> diff --git a/board/solidrun/clearfog/clearfog.c
>>> b/board/solidrun/clearfog/clearfog.c
>>> index 4019e37016..6c5b9a784f 100644
>>> --- a/board/solidrun/clearfog/clearfog.c
>>> +++ b/board/solidrun/clearfog/clearfog.c
>>> @@ -59,6 +59,9 @@ void config_static_serdes_map(void)
>>>  		board_serdes_map[4].serdes_speed = SERDES_SPEED_5_GBPS;
>>>  		board_serdes_map[4].serdes_mode = SERDES_DEFAULT_MODE;
>>>  	}
>>> +
>>> +	if (IS_ENABLED(CONFIG_CLEARFOG_SFP_25GB))
>>> +		board_serdes_map[5].serdes_speed = SERDES_SPEED_3_125_GBPS;
>>
>> config_static_serdes_map() is not called only when TLV EEPROM is
>> present. So CONFIG_CLEARFOG_SFP_25GB has no effect in that case. This
>> code should move to hws_board_topology_load() to avoid that.
>
> Yeah, that's what I was trying to ask with the question below embedded in
> patch 4.
>
>     "Note that this approach *does not* currently provide any mechanism
>     for EEPROM detected boards to have their SFP speed changed or switch
>     between PCIE/SATA signalling. I'm assuming that will be done based on
>     hardware detection, but confirmation/acceptance in review would be
>     appreciated so it can be revisited if needed.
>
> After sending the series and thinking about it more, I didn't see any other
> mechanism by which the configuration would be changed. The question was really
> to confirm what I had inferred from code, namely that Pro/Base boards even
> with EEPROM would still have to have a U-Boot built with custom options in
> order to change the PCIe/SATA or SFP options. I would like to confirm with you
> that is desired and expected even in the cases of EEPROM supporting units. If
> that's the case, I'll rework the location of setting, along with updating the
> help text for those options. Pending your confirmation, I plan to get rid of
> the separate config_static_serdes_map function and fold it back in, with the
> SATA and SFP options coming before the board runtime detection configuration.

My thinking is that EEPROM TLV is only meant to describe the hardware as
manufactured, and never change. SATA (read mSATA) and SFP are user setup
that TLV can't cover. So I think that SATA and SFP build time selection
should apply regardless of TLV.

In theory it could have been even better to store SATA/SFP selection in
environment variables. But that is not currently possible, since serdes
configuration takes place at SPL phase where the environment is not
accessible.

baruch

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