Re: [PATCH v2 5/5] configs: am335x_evm: Fix BeagleBone Green DTB selection

[Paul Barker <paul.barker@sancloud.com>]

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On Wed, 21 Jul 2021 11:29:04 +0530
Lokesh Vutla <lokeshvutla@ti.com> wrote:

> On 20/07/21 1:49 pm, Paul Barker wrote:
> > On Tue, 13 Jul 2021 11:59:06 +0530
> > Lokesh Vutla <lokeshvutla@ti.com> wrote:
> >   
> >> On 13/07/21 1:44 am, Paul Barker wrote:  
> >>> The function board_is_bone_lt() returns true for the BeagleBone Green,
> >>> the BeagleBone Enhanced and the BeagleBone Black. Therefore when
> >>> selecting which devicetree to use we must ensure that the more specific
> >>> functions board_is_bbg1() and board_is_bben() are checked first
> >>> otherwise all three devices would end up using the am335x-boneblack
> >>> devicetree. This can be achieved by placing the relevant devicetree
> >>> names (am335x-sancloud-bbe and am335x-bonegreen) before am335x-boneblack
> >>> in CONFIG_OF_LIST.    
> >>
> >> Such restrictions should be handled inside board_fit_config_name_match() and
> >> hiden from user configuration. Can you update the board_fit_config_name_match()
> >> instead of updating defconfig?  
> > 
> > Hi Lokesh,
> > 
> > Apologies for the late reply, I lost most of last week due to illness.
> > 
> > I first attempted to fix this by changing the order of things in
> > `board_fit_config_name_match` but it had no effect. Looking at
> > `fit_find_config_node` in `common/common_fit.c`, we loop through the
> > list of dtbs and check each one in turn for a match. So to move
> > am335x-bonegreen ahead of am335x-boneblack we need to change the order
> > in which the dtbs are checked in `fit_find_config_node`. The simplest
> > way I could find to do that is to change the order of the names in
> > CONFIG_OF_LIST.  
> 
> ahh..ok got it. But still such constraints in config file is most likely will
> not be maintained in future when someone touching the config. Because not
> everyone knows this.
> 
> Is it possible to create a new macro which is true only for bbb and use it
> instead in board_fit_config_name_match?

I'm happy to have a look for an alternative solution like that. The
patch here is a quick fix though that can be applied as-is. Perhaps we
should apply this and also look for an alternative implementation of
`board_is_bone_lt`.

If you want to leave this patch out for now, can we move ahead and
merge the other patches in this series?

Thanks,

-- 
Paul Barker
Principal Software Engineer
SanCloud Ltd

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