[HiassofT]

I did however have to enable CONFIG_BCM2708_POWER=y when building CONFIG_SPI_BCM2835=m and CONFIG_SPI_BCM2708=m - if I used CONFIG_BCM2708_POWER=m, the Pi/Pi2 wouldn't boot successfully.

Ah, sorry, I totally forgot about the power option. I had SPI set to modules before and enabled BCM2708_POWER=Y yesterday evening, as a consequence of kernel PR#980 - Kconfig has it as "default y".

Assuming all is well over the next few days then I'll submit a pull request to build SPI as modules for RPi/RPi2.

OpenELEC master hasn't updated the RPi kernel patch in quite a long time and some of the stuff like new power option or the need for the mailbox driver came after that. I think it might be best to submit a PR with the updated kernel patch and linux.arm.confs.

Here's the full config diff (minus the cirrus changes) I'm using in my build - it's in line with your config except I haven't enabled BCM_VC_SM

Code:

diff --git a/projects/RPi/linux/linux.arm.conf b/projects/RPi/linux/linux.arm.conf
index d3930b5..738c536 100644
--- a/projects/RPi/linux/linux.arm.conf
+++ b/projects/RPi/linux/linux.arm.conf
@@ -1449,8 +1449,8 @@ CONFIG_SPI_MASTER=y
# SPI Master Controller Drivers
#
# CONFIG_SPI_ALTERA is not set
-# CONFIG_SPI_BCM2835 is not set
-CONFIG_SPI_BCM2708=y
+CONFIG_SPI_BCM2835=m
+CONFIG_SPI_BCM2708=m
# CONFIG_SPI_BITBANG is not set
# CONFIG_SPI_CADENCE is not set
# CONFIG_SPI_GPIO is not set
@@ -3049,7 +3049,10 @@ CONFIG_COMMON_CLK=y
# CONFIG_SH_TIMER_TMU is not set
# CONFIG_EM_TIMER_STI is not set
# CONFIG_CLKSRC_VERSATILE is not set
-# CONFIG_MAILBOX is not set
+CONFIG_MAILBOX=y
+CONFIG_BCM2708_MBOX=y
+# CONFIG_PL320_MBOX is not set
+# CONFIG_ALTERA_MBOX is not set
# CONFIG_IOMMU_SUPPORT is not set

#
@@ -3064,6 +3067,7 @@ CONFIG_COMMON_CLK=y
#
# SOC (System On Chip) specific Drivers
#
+CONFIG_BCM2708_POWER=y
# CONFIG_SOC_TI is not set
# CONFIG_PM_DEVFREQ is not set
CONFIG_EXTCON=m
diff --git a/projects/RPi2/linux/linux.arm.conf b/projects/RPi2/linux/linux.arm.conf
index 9f6aa4f..c05a066 100644
--- a/projects/RPi2/linux/linux.arm.conf
+++ b/projects/RPi2/linux/linux.arm.conf
@@ -1501,8 +1501,8 @@ CONFIG_SPI_MASTER=y
# SPI Master Controller Drivers
#
# CONFIG_SPI_ALTERA is not set
-# CONFIG_SPI_BCM2835 is not set
-CONFIG_SPI_BCM2708=y
+CONFIG_SPI_BCM2835=m
+CONFIG_SPI_BCM2708=m
# CONFIG_SPI_BITBANG is not set
# CONFIG_SPI_CADENCE is not set
# CONFIG_SPI_GPIO is not set
@@ -3104,7 +3104,10 @@ CONFIG_ARM_ARCH_TIMER_EVTSTREAM=y
# CONFIG_SH_TIMER_TMU is not set
# CONFIG_EM_TIMER_STI is not set
# CONFIG_CLKSRC_VERSATILE is not set
-# CONFIG_MAILBOX is not set
+CONFIG_MAILBOX=y
+CONFIG_BCM2708_MBOX=y
+# CONFIG_PL320_MBOX is not set
+# CONFIG_ALTERA_MBOX is not set
# CONFIG_IOMMU_SUPPORT is not set

#
@@ -3119,6 +3122,7 @@ CONFIG_ARM_ARCH_TIMER_EVTSTREAM=y
#
# SOC (System On Chip) specific Drivers
#
+CONFIG_BCM2708_POWER=y
# CONFIG_SOC_TI is not set
# CONFIG_PM_DEVFREQ is not set
CONFIG_EXTCON=m

so long & thanks for your great work!

Hias