From: dillon min <dillon.minfei@xxxxxxxxx>
when do mmap on /dev/fb0, we will get -6 error on cortex-m3/m4 or armv7m
platform without cache support, this is caused by following reason:
on armv7m platform, if no cache support, we will use dma direct mapping,
but, this is not support on !MMU hardware, just return '-ENXIO' error
so, add use_reserved_mem() for these armv7m hardware but no-cache support.
eg, stm32f429/stm32f469.
verified on stm32f469-disco board, mmap frambuffer to userspace.
dillon min (2):
ARM: dts: stm32: Setup 4M bytes reserved memory for mmap
arm-nommu: Add use_reserved_mem() to check if device support reserved
memory
arch/arm/boot/dts/stm32f469-disco.dts | 14 ++++++++++++++
arch/arm/mm/dma-mapping-nommu.c | 28 +++++++++++++++++++++++++++-
2 files changed, 41 insertions(+), 1 deletion(-)
--
2.7.4
