[PATCH 4/4] drm/amdgpu: used cached gca values for vi_read_register

[Andy Furniss]

Alex Deucher wrote:
> Using the cached values has less latency for bare metal and SR-IOV,
> and prevents reading back bogus values if the engine is powergated.

I can't startx since this on r9285.

Seems there are further issues later in current 4.9-wip = I die on
driver load, will see if that's related or one of Christians patches later.

Also anyone on list have shutdown/reboot issues - I can't for the past
few 4.9-wips (I did tag on to someone elses bug, but that's gone quiet).

One thing at a time this commit for me, boots into fbcon OK but then
segfaults -

[    19.694] (II) AIGLX: Loaded and initialized radeonsi
[    19.694] (II) GLX: Initialized DRI2 GL provider for screen 0
[    19.694] (EE)
[    19.694] (EE) Backtrace:
[    19.717] (EE) 0: /usr/libexec/Xorg (OsSigHandler+0x29) [0x5853b9]
[    19.726] (EE) 1: /lib/libc.so.6 (killpg+0x40) [0x7f97e86cb68f]
[    19.756] (EE) 2: /usr/lib/dri/radeonsi_dri.so 
(amdgpu_surface_init+0x486) [0x7f97e1a40746]
[    19.757] (EE) 3: /usr/lib/dri/radeonsi_dri.so 
(r600_texture_create_object+0xd7) [0x7f97e1a5dfe7]
[    19.759] (EE) 4: /usr/lib/dri/radeonsi_dri.so 
(r600_texture_create+0x75) [0x7f97e1a5ea15]
[    19.771] (EE) 5: /usr/lib/dri/radeonsi_dri.so 
(st_texture_create+0x5b) [0x7f97e178af1b]
[    19.773] (EE) 6: /usr/lib/dri/radeonsi_dri.so 
(guess_and_alloc_texture+0x1ac) [0x7f97e173ae9c]
[    19.774] (EE) 7: /usr/lib/dri/radeonsi_dri.so 
(st_AllocTextureImageBuffer+0x3a4) [0x7f97e173b3d4]
[    19.775] (EE) 8: /usr/lib/dri/radeonsi_dri.so (st_TexImage+0x6c) 
[0x7f97e173f9ac]
[    19.786] (EE) 9: /usr/lib/dri/radeonsi_dri.so 
(_mesa_get_fallback_texture+0x193) [0x7f97e16cb763]
[    19.786] (EE) 10: /usr/lib/dri/radeonsi_dri.so 
(_mesa_update_texture+0x1a7) [0x7f97e16d1c37]
[    19.787] (EE) 11: /usr/lib/dri/radeonsi_dri.so 
(_mesa_update_state_locked+0x683) [0x7f97e16b00e3]
[    19.787] (EE) 12: /usr/lib/dri/radeonsi_dri.so 
(_mesa_update_state+0x11) [0x7f97e16b0441]
[    19.787] (EE) 13: /usr/lib/dri/radeonsi_dri.so 
(_mesa_EGLImageTargetTexture2DOES+0x168) [0x7f97e16c5c88]
[    19.802] (EE) 14: /usr/lib/xorg/modules/libglamoregl.so 
(glamor_create_texture_from_image+0xaa) [0x7f97d93bf89a]
[    19.803] (EE) 15: /usr/lib/xorg/modules/libglamoregl.so 
(glamor_egl_create_textured_pixmap+0x12d) [0x7f97d93bfafd]
[    19.803] (EE) 16: /usr/lib/xorg/modules/libglamoregl.so 
(glamor_egl_create_textured_screen+0x33) [0x7f97d93bfc23]
[    19.811] (EE) 17: /usr/lib/xorg/modules/drivers/amdgpu_drv.so 
(amdgpu_glamor_create_screen_resources+0x67) [0x7f97e2ea7cf7]
[    19.812] (EE) 18: /usr/lib/xorg/modules/drivers/amdgpu_drv.so 
(AMDGPUCreateScreenResources_KMS+0x27e) [0x7f97e2e9fe3e]
[    19.813] (EE) 19: /usr/libexec/Xorg 
(xf86CrtcCreateScreenResources+0x2e) [0x4a3b7e]
[    19.814] (EE) 20: /usr/libexec/Xorg (dix_main+0x26e) [0x438ebe]
[    19.815] (EE) 21: /lib/libc.so.6 (__libc_start_main+0xf0) 
[0x7f97e86b85e0]
[    19.816] (EE) 22: /usr/libexec/Xorg (_start+0x29) [0x424659]
[    19.816] (EE)
[    19.816] (EE) Segmentation fault at address 0x4023321cc
[    19.816] (EE)
Fatal server error:
[    19.816] (EE) Caught signal 11 (Segmentation fault). Server aborting