[U-Boot] U-Boot, avr32: compiler warning with

[Heiko Schocher]

Hello Simon,

I see an compile error for avr32 on travis.org for current mainline
U-Boot, see [1].

git bisecting it, with the information that last working avr32 build
on travis.org is [2], shows:

pollux:u-boot hs [(kein Branch, binäre Suche begonnen bei 20151116)] $ git bisect log
git bisect start
# good: [a5325cd5e91f77a2214e80198ae31c1d8b7e7c3c] configs: Remove CONFIG_SERIAL_MULTI
git bisect good a5325cd5e91f77a2214e80198ae31c1d8b7e7c3c
# bad: [ae27120c31d58b8bb694d9155bcffdcfae8552a6] Merge git://git.denx.de/u-boot-dm
git bisect bad ae27120c31d58b8bb694d9155bcffdcfae8552a6
# bad: [bae34335e8aef46d7103907580c40f18f1876bb0] exynos: Remove unneeded device tree control #ifdefs
git bisect bad bae34335e8aef46d7103907580c40f18f1876bb0
# bad: [f615e6a64d23952d3c68b9ac92b4ef5fa5ebdf8a] dm: power: Add support for S5M8767 regulators
git bisect bad f615e6a64d23952d3c68b9ac92b4ef5fa5ebdf8a
# bad: [f1ac35b7a6c6bc878d473b5955370b1cc49dba54] exynos: dts: Sync up I2C ports with the kernel
git bisect bad f1ac35b7a6c6bc878d473b5955370b1cc49dba54
# good: [7fc65bcf8a0a5463db86efbb273a40448c845efc] dm: i2c: Move definitions to the top of the 
header file
git bisect good 7fc65bcf8a0a5463db86efbb273a40448c845efc
# bad: [b725dc458f9db44957d4f541d05defe178dda7b5] i2c: Add a mux for GPIO-based I2C bus arbitration
git bisect bad b725dc458f9db44957d4f541d05defe178dda7b5
# bad: [3d1957f0ea0133ec06f9c6fd85dc1acdf66ad29c] dm: i2c: Add support for multiplexed I2C buses
git bisect bad 3d1957f0ea0133ec06f9c6fd85dc1acdf66ad29c
# good: [df358c6beca8f7cc2f2b67c54f0bf255ebd5cc22] dm: i2c: Add a function to transfer messages
git bisect good df358c6beca8f7cc2f2b67c54f0bf255ebd5cc22
# first bad commit: [3d1957f0ea0133ec06f9c6fd85dc1acdf66ad29c] dm: i2c: Add support for multiplexed 
I2C buses
pollux:u-boot hs [(kein Branch, binäre Suche begonnen bei 20151116)] $

Hmm... it seems, that introducing the subdir "muxes" leads into
this error for avr32 ... I just tried the following patch:

diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index 32198bd..811ad9b 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -40,4 +40,4 @@ obj-$(CONFIG_SYS_I2C_UNIPHIER) += i2c-uniphier.o
  obj-$(CONFIG_SYS_I2C_UNIPHIER_F) += i2c-uniphier-f.o
  obj-$(CONFIG_SYS_I2C_ZYNQ) += zynq_i2c.o

-obj-y += muxes/
+obj-$(CONFIG_I2C_MUX) += muxes/
pollux:u-boot hs [20151116] $

and the error "drivers/i2c/built-in.o: warning: input is not relaxable"
is gone ...

Do you have an idea, why this breaks? Is above patch a valid fix?
(I checked, that all boards using CONFIG_I2C_ARB_GPIO_CHALLENGE have
  also set CONFIG_I2C_MUX)

bye,
Heiko
[1] current U-Boot compile error for avr32 on travis.org:
https://travis-ci.org/u-boot/u-boot/jobs/90954387

[2] last working U-Boot compile on travis.org for avr32:
https://travis-ci.org/u-boot/u-boot/builds/74310800
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