[U-Boot] [PATCH v2 3/3] common: Generic loader for file system

[Simon Glass]

Hi,

On 11 June 2018 at 08:15, Marek Vasut <marex at denx.de> wrote:
> On 06/11/2018 04:13 PM, Chee, Tien Fong wrote:
>> On Mon, 2018-06-11 at 16:03 +0200, Marek Vasut wrote:
>>> On 06/11/2018 03:55 PM, Chee, Tien Fong wrote:
>>> [...]
>>>>
>>>>>
>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> Linux firmware loading method is different with this
>>>>>>>> Linux loading firmware with
>>>>>>>> 1. Firmware search paths - which is hardcoded in root file
>>>>>>>> system
>>>>>>>> 2. Built-in firmware - part of kernel binaries
>>>>>>>>
>>>>>>>> This patch loading firmware with
>>>>>>>> 1. Storage type and partition specified in DTS, but storage
>>>>>>>> type
>>>>>>>> can
>>>>>>>> be overridden dev instance and partition through U-boot
>>>>>>>> variable
>>>>>>>> environment.
>>>>>>>>
>>>>>>>> Or:
>>>>>>>>
>>>>>>>> 2. Storage type can be set through dev instance, and
>>>>>>>> partition
>>>>>>>> through
>>>>>>>> U-boot variable environment. No DTS is required.
>>>>>>> And why can we not do as Linux does ?
>>>>>>>
>>>>>> Because we don't have root file system, but i have mimicked the
>>>>>> search
>>>>>> path in our variable environment, but with both storage type
>>>>>> and
>>>>>> partition.
>>>>> OK, so user can configure environment variable to inform U-Boot
>>>>> where
>>>>> to
>>>>> look for firmware, good (although, this probably fails in early
>>>>> env,
>>>>> dunno of that's a problem).
>>>>>
>>>> Without DTS, then you need to configure env variable, so that SPL
>>>> and
>>>> U-boot only know what storage type and partiton to look for
>>>> firmware.
>>> I guess that's fine ?
>>>
>> Yes, it is already supported in this patches.
>>>>
>>>>>
>>>>> But why do we need the DT part of things ? I don't think we do
>>>>> need
>>>>> it
>>>>> at all.
>>>>>
>>>> Leverage the flexibility and benefits of the DT such as changing
>>>> both
>>>> storage type and partitions without changing the codes.
>>> DT is a hardware description. Does this describe hardware ? No
>>>
>> Okay, then i will remove DT part.
>
> Wait for feedback from sjg at least.

I think using device tree is fine for this, but I suggest that the
binding file (when you add it) should mention that the node for this
driver should go in /chosen. That's what we use for settings, etc.

Things to do:
- Add a sandbox driver for this uclass, and a test in test/dm/...
- Add some documentation about it somehwere
- Add a device-tree binding file - see doc/device-tree-bindings

Regards,
Simon