Hello Hiep, On Monday 23 Jan 2017 16:58:34 Hiep Cao Minh wrote: > > On Friday 20 Jan 2017 12:11:50 DongCV wrote: > >> Dear Mr Laurent, > >> > >> Thank you for your quick reply. > >> This is the log file contains information about the command "modetest -M > >> rcar-du" (with the HDMI cable plugged). > > > > Thank you. I think I know what's wrong. The default mode picked by the > > system in your case uses positive H/V sync polarities, while in my cases > > the sync signals have negative polarities. Could you try to select > > 1024x768 @60Hz instead of 1024x768 @75Hz ? I think the HDMI output would > > then work correctly, which would confirm that the problem is indeed > > caused by sync polarities. > > Dong is sick, so he did not attend today. He will reply to you tomorrow. > Could you explain more how to set 1024x768 @60Hz and negative polarities > for the HDMI output?, I've investigated the problem further here now that I'm back home with access to my Lager board, but have been unable to reproduce it even by testing all sync signal polarities. First of all, the "CMA enabled" kernel configuration file attached to a previous e-mail in this series indeed enables CMA, but doesn't enable CMA usage for DMA buffers. You need to additionally set CONFIG_DMA_CMA=y CONFIG_CMA_SIZE_MBYTES=128 The amount of CMA memory to reserve can vary depending on the tests you perform. The larger the resolutions and the number of buffers are, the more memory you will need. 128MB should be a safe bet for most cases. Feel free to reduce that if you need to use a lot of memory outside of CMA, or increase it if you run into buffer allocation failures with multimedia devices (DU, VIN, VSP, ...). You can then let the HDMI cable plugged at all time and you should not get framebuffer allocation failures when booting the board with the cable plugged in. Then, I tried to modify the H/V sync polarities by using different video modes. If you look at the output of "modetest -M rcar-du", you should get a list of modes similar to the following for the HDMI output. 1440x900 60 1440 1520 1672 1904 900 903 909 934 flags: nhsync, pvsync 1280x1024 75 1280 1296 1440 1688 1024 1025 1028 1066 flags: phsync, pvsync 1280x1024 60 1280 1328 1440 1688 1024 1025 1028 1066 flags: phsync, pvsync 1440x900 75 1440 1536 1688 1936 900 903 909 942 flags: nhsync, pvsync 1280x800 60 1280 1328 1360 1440 800 803 809 823 flags: phsync, nvsync 1152x864 75 1152 1216 1344 1600 864 865 868 900 flags: phsync, pvsync 1024x768 75 1024 1040 1136 1312 768 769 772 800 flags: phsync, pvsync 1024x768 70 1024 1048 1184 1328 768 771 777 806 flags: nhsync, nvsync 1024x768 60 1024 1048 1184 1344 768 771 777 806 flags: nhsync, nvsync 832x624 75 832 864 928 1152 624 625 628 667 flags: nhsync, nvsync 800x600 75 800 816 896 1056 600 601 604 625 flags: phsync, pvsync 800x600 72 800 856 976 1040 600 637 643 666 flags: phsync, pvsync 800x600 60 800 840 968 1056 600 601 605 628 flags: phsync, pvsync 800x600 56 800 824 896 1024 600 601 603 625 flags: phsync, pvsync 640x480 75 640 656 720 840 480 481 484 500 flags: nhsync, nvsync 640x480 73 640 664 704 832 480 489 492 520 flags: nhsync, nvsync 640x480 67 640 704 768 864 480 483 486 525 flags: nhsync, nvsync 640x480 60 640 656 752 800 480 490 492 525 flags: nhsync, nvsync 720x400 70 720 738 846 900 400 412 414 449 flags: nhsync, pvsync Each mode has a defined horizontal and vertical polarity. If you pick your modes carefully you will be able to test all four combinations of polarities. I tried them all, and couldn't reproduce the reported problem with the test procedure that Dong specified. The easiest way to select a video mode for the fbdev compatibility layer is to specify it as the default mode on the kernel command line using the video= argument. The mode value is in the form of <width>x<height>@<refresh rate>. For instance, to select the 1024x768 75Hz mode, simply add video=1024x768@75 to the kernel command line arguments (there are multiple ways to do so depending on how you configured your boot loader, I personally like to modify the bootargs value in the .dts file for the board). Could you please check if the problem occurs with all video modes supported by your HDMI monitor or with some of them only ? -- Regards, Laurent Pinchart
