Description of problem: After a fresh install of Fedora 18 on an Mac Mini 2012 (Core i5 model), display shows serious banding (wallpaper, viewing photos), probably because only 256 colors are used. Version-Release number of selected component (if applicable): [ 28.464] (II) Loading /usr/lib64/xorg/modules/drivers/intel_drv.so [ 28.494] (II) Module intel: vendor="X.Org Foundation" [ 28.494] compiled for 1.13.0, module version = 2.20.17 [ 28.494] Module class: X.Org Video Driver [ 28.494] ABI class: X.Org Video Driver, version 13.0 How reproducible: Occurs on every boot. Steps to Reproduce: 1. Install Fedora 18 on mac mini, using EFI, without using bootcamp. 2. boot system 3. Observe strong banding on fine gradients, such as the default background image. Additional info: /var/log/Xorg.0.log seems to indicate that a 24 bit depth is used: [ 28.499] (II) intel(0): Creating default Display subsection in Screen section "Default Screen Section" for depth/fbbpp 24/32 [ 28.499] (==) intel(0): Depth 24, (--) framebuffer bpp 32 However, when do manually start X with 8 or 24 bits, the screen shows the same banding. $ init 3 $ startx -- -depth 8 [logout] $ startx -- -depth 24
Odd. Can you install the 'intel-gpu-tools' package, and then attach the output from running 'intel_reg_dumper' as root? I suspect we're just getting dithering wrong rather than actually using an 8bpp framebuffer.
Created attachment 686103 [details] Output of sudo intel_reg_dumper Here is the output of intel_reg_dumper
In the meantime, I have tried different things: A screen shot made with the "Print screen" key under Gnome 3 contains all the colors when viewed on another machine. On the screen, dark colors are especially bad, so I guess it is really the dithering. Today I noticed that a normal color appearance. I did rebooted the machine a couple of times and switched to OSX in between. Unfortunately, I haven't noticed what made the colors look right. I saved the intel_reg_dumper output when I got the good colors (intel_reg_dumper_nodithering.txt), and it is slightly different from the initial output. Here is the diff: --- intel_reg_dumper_dither_old.txt 2013-01-27 13:45:28.000000000 +0100 +++ intel_reg_dumper_nodithering.txt 2013-01-27 13:44:42.000000000 +0100 @@ -11,7 +11,7 @@ DISPLAY_PORT_PLL_BIOS_1: 0x00000000 DISPLAY_PORT_PLL_BIOS_2: 0x00000000 FDI_PLL_FREQ_CTL: 0x00000000 - PIPEACONF: 0xc1000000 (enabled, active, pf-pd, rotate 0, 8bpc) + PIPEACONF: 0xc0000000 (enabled, active, pf-pd, rotate 0, 8bpc) HTOTAL_A: 0x069704ff (1280 active, 1688 total) HBLANK_A: 0x069704ff (1280 start, 1688 end) HSYNC_A: 0x059f052f (1328 start, 1440 end) @@ -22,12 +22,12 @@ PIPEASRC: 0x04ff03ff (1280, 1024) PIPEA_DATA_M1: 0x7e278d00 (TU 64, val 0x278d00 2592000) PIPEA_DATA_N1: 0x0041eb00 (val 0x41eb00 4320000) - PIPEA_DATA_M2: 0x7e4ccccc (TU 64, val 0x4ccccc 5033164) - PIPEA_DATA_N2: 0x00800000 (val 0x800000 8388608) + PIPEA_DATA_M2: 0x00000000 (TU 1, val 0x0 0) + PIPEA_DATA_N2: 0x00000000 (val 0x0 0) PIPEA_LINK_M1: 0x0001a5e0 (val 0x1a5e0 108000) PIPEA_LINK_N1: 0x00041eb0 (val 0x41eb0 270000) - PIPEA_LINK_M2: 0x00003333 (val 0x3333 13107) - PIPEA_LINK_N2: 0x00008000 (val 0x8000 32768) + PIPEA_LINK_M2: 0x00000000 (val 0x0 0) + PIPEA_LINK_N2: 0x00000000 (val 0x0 0) DSPACNTR: 0xd8004400 (enabled) DSPABASE: 0x00000000 DSPASTRIDE: 0x00001400 (80) @@ -83,12 +83,12 @@ PFA_CTL_4: 0x00007d80 (hscale 0.980469) PFA_WIN_POS: 0x00000000 (0, 0) PFA_WIN_SIZE: 0x00000000 (0, 0) - PFB_CTL_1: 0x00800000 (disable, auto_scale yes, auto_scale_cal no, v_filter enable, vadapt disable, mode least, filter_sel hardcoded,chroma pre-filter disable, vert3tap auto, v_inter_invert field 1) - PFB_CTL_2: 0x00008000 (vscale 1.000000) - PFB_CTL_3: 0x00004000 (vscale initial phase 0.500000) - PFB_CTL_4: 0x00008000 (hscale 1.000000) + PFB_CTL_1: 0x00000000 (disable, auto_scale yes, auto_scale_cal no, v_filter enable, vadapt disable, mode least, filter_sel programmed,chroma pre-filter disable, vert3tap auto, v_inter_invert field 1) + PFB_CTL_2: 0x00007e00 (vscale 0.984375) + PFB_CTL_3: 0x00003f00 (vscale initial phase 0.492188) + PFB_CTL_4: 0x00007d80 (hscale 0.980469) PFB_WIN_POS: 0x00000000 (0, 0) - PFB_WIN_SIZE: 0x05000400 (1280, 1024) + PFB_WIN_SIZE: 0x00000000 (0, 0) PFC_CTL_1: 0x00000000 (disable, auto_scale yes, auto_scale_cal no, v_filter enable, vadapt disable, mode least, filter_sel programmed,chroma pre-filter disable, vert3tap auto, v_inter_invert field 1) PFC_CTL_2: 0x00007e00 (vscale 0.984375) PFC_CTL_3: 0x00003f00 (vscale initial phase 0.492188) @@ -162,7 +162,7 @@ FDI_RXA_CTL: 0x8c082b50 (enable, train pattern not train, port width X2, 8bpc,link_reverse_strap_overwrite no, dmi_link_reverse no, FDI PLL enable,FS ecc enable, FE ecc disable, FS err report enable, FE err report enable,scrambing enable, enhanced framing enable, PCDClk) FDI_RXB_CTL: 0x00000040 (disable, train pattern pattern_1, port width X1, 8bpc,link_reverse_strap_overwrite no, dmi_link_reverse no, FDI PLL disable,FS ecc disable, FE ecc disable, FS err report disable, FE err report disable,scrambing enable, enhanced framing enable, RawClk) FDI_RXC_CTL: 0x00000040 (disable, train pattern pattern_1, port width X1, 8bpc,link_reverse_strap_overwrite no, dmi_link_reverse no, FDI PLL disable,FS ecc disable, FE ecc disable, FS err report disable, FE err report disable,scrambing enable, enhanced framing enable, RawClk) - FDI_RXA_MISC: 0x00200080 (FDI Delay 128) + FDI_RXA_MISC: 0x00000080 (FDI Delay 128) FDI_RXB_MISC: 0x00000080 (FDI Delay 128) FDI_RXC_MISC: 0x00000080 (FDI Delay 128) FDI_RXA_TUSIZE1: 0x7e000000 @@ -199,8 +199,8 @@ PCH_PP_OFF_DELAYS: 0x00000000 PCH_PP_DIVISOR: 0x00186904 PORT_DBG: 0x00007007 (HW DRRS off) - RC6_RESIDENCY_TIME: 0x00a7dc68 - RC6p_RESIDENCY_TIME: 0x91dc0a37 + RC6_RESIDENCY_TIME: 0x222303b1 + RC6p_RESIDENCY_TIME: 0x6c0e6f55 RC6pp_RESIDENCY_TIME: 0x00000000 GEN6_RP_CONTROL: 0x00000d91 (enabled) GEN6_RPNSWREQ: 0x0e000000 Afterwards, I turned off the computer and started it a again. The dithering appeared again, and the intel reg dump looks very similar to the initial one: --- intel_reg_dumper_dither_old.txt 2013-01-27 13:45:28.000000000 +0100 +++ intel_reg_dumper_dither_new.txt 2013-01-27 20:45:29.867867289 +0100 @@ -31,7 +31,7 @@ DSPACNTR: 0xd8004400 (enabled) DSPABASE: 0x00000000 DSPASTRIDE: 0x00001400 (80) - DSPASURF: 0x00a73008 + DSPASURF: 0x04446008 DSPATILEOFF: 0x00000000 (0, 0) PIPEBCONF: 0x00000000 (disabled, inactive, pf-pd, rotate 0, 8bpc) HTOTAL_B: 0x00000000 (1 active, 1 total) @@ -199,8 +199,8 @@ PCH_PP_OFF_DELAYS: 0x00000000 PCH_PP_DIVISOR: 0x00186904 PORT_DBG: 0x00007007 (HW DRRS off) - RC6_RESIDENCY_TIME: 0x00a7dc68 - RC6p_RESIDENCY_TIME: 0x91dc0a37 + RC6_RESIDENCY_TIME: 0x0134edad + RC6p_RESIDENCY_TIME: 0x78ed40ec RC6pp_RESIDENCY_TIME: 0x00000000 GEN6_RP_CONTROL: 0x00000d91 (enabled) GEN6_RPNSWREQ: 0x0e000000 I hope that gives some insight into this problem. Please let me know if you need more information. Thanks, Pablo
After looking at the differences in the listings and the VOL_3_display_registers.pdf file, I tried the following: intel_reg_write 0x70008 0xC0000000 This did indeed remove the banding effect, and images now look as they should. Do you know which software component is responsible for setting up the PIPEACONF register? The intel driver or the kernel?
I'm experience the same issue with late 2012 i7 model and Fedora 18 x86_64. The workaround in comment 4 also fixes the issue for me. But I've also noticed that if I boot the machine without any monitors attached and plug the monitor after the graphical boot starts then the colors are ok.
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