On 11/20/2014 09:44 AM, Simon Glass wrote:
Hi Masahiro,
On 19 November 2014 09:21, Masahiro Yamada <[email protected]> wrote:
Hi Simon,
On Tue, 18 Nov 2014 14:37:33 +0000
Simon Glass <[email protected]> wrote:
Hi Masahiro,
On 18 November 2014 12:51, Masahiro Yamada <[email protected]> wrote:
Hi Simon,
On Mon, 17 Nov 2014 18:17:43 +0000
Simon Glass <[email protected]> wrote:
Hi Masahiro,
On 17 November 2014 08:19, Masahiro Yamada <[email protected]> wrote:
The driver model provides two ways to pass the device information,
platform data and device tree. Either way works to bind devices and
drivers, but there is inconsistency in terms of how to pass the
pre-reloc flag.
In the platform data way, the pre-reloc DM scan checks if each driver
has DM_FLAG_PRE_RELOC flag (this was changed to use U_BOOT_DRIVER_F
just before). That is, each **driver** has the pre-reloc attribute.
In the device tree control, the existence of "u-boot,dm-pre-reloc" is
checked for each device node. The driver flag "DM_FLAG_PRE_RELOC" is
never checked. That is, each **device** owns the pre-reloc attribute.
Drivers should generally work both with platform data and device tree,
but this inconsistency has made our life difficult.
I feel we should use device tree where available, and only fall back
to platform data when necessary (no device tree available for
platform, for example).
No, it is true that device tree is a useful tool, but it should be optional.
All the infrastructures of drivers must work perfectly without device tree.
The device tree is just one choice of how to give device information.
Which platform(s) are we talking about here?
I am talking about the general design policy of drivers
in U-Boot and Linux.
Well Linux has moved away from platform data, right?
As a blanket statement, that isn't true.
Some architectures (e.g. ARM) have moved to DT. That move is something
done by the ARM maintainers, not something that's necessarily being
forced upon every single architecture. I know of no move to force
everyone to convert to DT.
What makes sense for Linux doesn't always make sense for everything else
anyway.
In my opinion, DT in Linux isn't actually doing much that's useful, and
DT in a boot loader is likely to be even less useful.
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