[PATCH v5 12/12] arm: mvebu: clearfog: Use Pro DT by default

[Joel Johnson]

On 2020-01-27 23:17, Baruch Siach wrote:
> Hi Joel,
> 
> On Mon, Jan 27, 2020 at 01:01:56PM -0700, Joel Johnson wrote:
>> Switch to explicitly using the Pro variant DT, which has been
>> available since Linux 4.11.
>> 
>> ---
>> 
>> v4 changes:
>>   - new
>> v5 changes:
>>   - none
>> 
>> I separated out this change to the end of the series since it drew
>> questioning on prior review. I'd still advocate for making the change,
>> since especially with the additions of static variants and runtime
>> detection, it becomes easier from within a booted kernel to identify 
>> the
>> type and version of U-Boot image installed. Without making this 
>> change,
>> it becomes less direct to determine an actual Pro vs. Base, vs old
>> U-Boot image maybe supporting some hybrid variant configuration.
>> 
>> Even in the Linux kernel adding of the Pro DTS, it is indicated that 
>> it
>> was meant for backwards compatibility.
>> 
>> Except for cases where checking is done directly against the product
>> name from userspace, I don't see downsides even from a compatibility
>> perspective for not making this change. In cases where checking *is*
>> done from userspace, the broadening of the Clearfog product line would
>> seem to mean that userspace checking should be flagged as needing to 
>> be
>> udpated as well (or glob/regex matched as needed).
> 
> One downside I see is that boot of kernels older than 4.11 will fail. 
> But
> maybe since we already assume a newer kernel for 
> armada-388-clearfog-base.dtb
> we can do that for -pro as well.

Older kernels is one case, and to be fair there may also be the case of 
custom images with a newer kernel that for whatever reason (old file 
glob patterns) don't ship the -pro.dtb file. My testing focused 
primarily on OpenWRT and Debian, and while certainly not pervasive, I've 
also tested with current Armbian and Arch Linux ARM builds.

> By the way, does env_set() override the stored environment?

I'm not entirely sure of the behavior with duplicate entries, however 
patch 7 in the series removes the fdtfile entry from being added via 
CONFIG_EXTRA_ENV_SETTINGS, so it is now only set in one consistent 
location within board_late_init().

Joel