i915 with valleyview

[Sudip Mukherjee]

Hi Daniel,
I am trying to use i915 in one of our board which has Intel ATOM E3840.
I know Intel has released emgd driver for this cpu to use i915 but emgd
is not supported on v4.5 (or v4.6). The board is having SFI (simple
firmware interface) and maybe for that i915 is not finding the VBIOS and
other required information. I have turned on drm debugging and some
parts of it are:
[    0.390846] [drm] Initialized drm 1.1.0 20060810
[    0.390875] i915 0000:00:02.0: PCI->APIC IRQ transform: INT A -> IRQ 16
<snip>
[    0.391595] [drm:i915_dump_device_info] i915 device info: gen=7, pciid=0x0f31 rev=0x0a flags=is_mobile,need_gfx_hws,is_valleyview,has_hotplug,
[    0.391615] [drm:intel_detect_pch] No PCH found.
[    0.391760] [drm] Memory usable by graphics device = 2048M
[    0.391764] [drm:i915_gem_gtt_init] GMADR size = 256M
[    0.391767] [drm:i915_gem_gtt_init] GTT stolen size = 64M
[    0.391770] [drm:sanitize_enable_ppgtt] disabling PPGTT on pre-B3 step VLV

I can see that four connectors are registered. But I am also seeing-

[    2.143214] [drm:intel_crt_detect] [CONNECTOR:29:VGA-1] force=1
[    2.143216] [drm:intel_power_well_enable] enabling display
[    2.149314] [drm:i915_redisable_vga_power_on] Something enabled VGA plane, disabling it
[    2.149627] [drm:intel_power_well_enable] enabling dpio-common
[    2.157670] [drm:valleyview_crt_detect_hotplug] trigger hotplug detect cycle: adpa=0x40000
[    2.161690] [drm:valleyview_crt_detect_hotplug] valleyview hotplug adpa=0x40000, result 0
[    2.161692] [drm:intel_crt_detect] CRT not detected via hotplug
[    2.168780] [drm:drm_do_probe_ddc_edid] drm: skipping non-existent adapter i915 gmbus vga
[    2.168782] [drm:intel_crt_detect_ddc] CRT not detected via DDC:0x50 [no valid EDID found]
[    2.168783] [drm:intel_power_well_disable] disabling dpio-common
[    2.176832] [drm:intel_power_well_disable] disabling display
[    2.186894] [drm:drm_helper_probe_single_connector_modes_merge_bits] [CONNECTOR:29:VGA-1] disconnected

Same thing happens for all the other connectors.

I will greatly appreciate any help or pointer to something which can
make i915 work in this scenario. Maybe there is some option where I can
provide the configuration to i915 manually rather than depending on
hotplog/edid or some other way which I am missing.

Regards
Sudip