我现在使用的是3.8.13 的镜像文件，使用MicroHDMI转VGA，将beaglebone black的板子连接到一个VGA的显示器上，但是启动时出现以下错误：
[ 2.107962] tilcdc 4830e000.fb: found TDA19988
[ 2.113276] [drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
[ 2.120184] [drm] No driver support for vblank timestamp query.
[ 2.517543] tilcdc 4830e000.fb: failed to read EDID
[ 2.525482] ------------[ cut here ]------------
[ 2.525506] WARNING: at drivers/gpu/drm/tilcdc/tilcdc_crtc.c:251 tilcdc_crtc_mode_set+0x3b/0x464()
[ 2.525514] Modules linked in:
[ 2.525549] [<c0010881>] (unwind_backtrace+0x1/0x8c) from [<c002c3bf>] (warn_slowpath_common+0x33/0x48)
[ 2.525562] [<c002c3bf>] (warn_slowpath_common+0x33/0x48) from [<c002c3e3>] (warn_slowpath_null+0xf/0x10)
[ 2.525575] [<c002c3e3>] (warn_slowpath_null+0xf/0x10) from [<c02451ff>] (tilcdc_crtc_mode_set+0x3b/0x464)
[ 2.525594] [<c02451ff>] (tilcdc_crtc_mode_set+0x3b/0x464) from [<c0235711>] (drm_crtc_helper_set_mode+0x147/0x22e)
[ 2.525608] [<c0235711>] (drm_crtc_helper_set_mode+0x147/0x22e) from [<c0235cbb>] (drm_crtc_helper_set_config+0x423/0x5e8)
[ 2.525621] [<c0235cbb>] (drm_crtc_helper_set_config+0x423/0x5e8) from [<c0234f05>] (drm_fb_helper_set_par+0x39/0x74)
[ 2.525637] [<c0234f05>] (drm_fb_helper_set_par+0x39/0x74) from [<c0206e57>] (fbcon_init+0x21b/0x2ec)
[ 2.525655] [<c0206e57>] (fbcon_init+0x21b/0x2ec) from [<c0225865>] (visual_init+0x71/0xb4)
[ 2.525670] [<c0225865>] (visual_init+0x71/0xb4) from [<c0226a3f>] (do_bind_con_driver+0x121/0x20e)
[ 2.525684] [<c0226a3f>] (do_bind_con_driver+0x121/0x20e) from [<c0226b7d>] (do_take_over_console+0x23/0x26)
[ 2.525696] [<c0226b7d>] (do_take_over_console+0x23/0x26) from [<c0206f5f>] (do_fbcon_takeover+0x37/0x78)
[ 2.525717] [<c0206f5f>] (do_fbcon_takeover+0x37/0x78) from [<c00413f5>] (notifier_call_chain+0x21/0x3a)
[ 2.525732] [<c00413f5>] (notifier_call_chain+0x21/0x3a) from [<c00414b9>] (__blocking_notifier_call_chain+0x27/0x34)
[ 2.525745] [<c00414b9>] (__blocking_notifier_call_chain+0x27/0x34) from [<c00414d5>] (blocking_notifier_call_chain+0xf/0x10)
[ 2.525769] [<c00414d5>] (blocking_notifier_call_chain+0xf/0x10) from [<c0201f85>] (register_framebuffer+0x131/0x174)
[ 2.525782] [<c0201f85>] (register_framebuffer+0x131/0x174) from [<c023504b>] (drm_fb_helper_single_fb_probe+0x10b/0x184)
[ 2.525795] [<c023504b>] (drm_fb_helper_single_fb_probe+0x10b/0x184) from [<c02351c1>] (drm_fb_helper_initial_config+0xfd/0x134)
[ 2.525809] [<c02351c1>] (drm_fb_helper_initial_config+0xfd/0x134) from [<c023657f>] (drm_fbdev_cma_init+0x71/0x96)
[ 2.525824] [<c023657f>] (drm_fbdev_cma_init+0x71/0x96) from [<c0246ea9>] (tilcdc_load+0x3b7/0x3de)
[ 2.525839] [<c0246ea9>] (tilcdc_load+0x3b7/0x3de) from [<c023cad9>] (drm_get_platform_dev+0x9f/0x14a)
[ 2.525856] [<c023cad9>] (drm_get_platform_dev+0x9f/0x14a) from [<c024b3e1>] (platform_drv_probe+0xd/0xe)
[ 2.525869] [<c024b3e1>] (platform_drv_probe+0xd/0xe) from [<c024a997>] (driver_probe_device+0x67/0x144)
[ 2.525880] [<c024a997>] (driver_probe_device+0x67/0x144) from [<c024aaa9>] (__driver_attach+0x35/0x48)
[ 2.525891] [<c024aaa9>] (__driver_attach+0x35/0x48) from [<c0249ac5>] (bus_for_each_dev+0x29/0x48)
[ 2.525903] [<c0249ac5>] (bus_for_each_dev+0x29/0x48) from [<c024a45b>] (bus_add_driver+0x83/0x158)
[ 2.525914] [<c024a45b>] (bus_add_driver+0x83/0x158) from [<c024ad89>] (driver_register+0x4d/0xa4)
[ 2.525926] [<c024ad89>] (driver_register+0x4d/0xa4) from [<c0008745>] (do_one_initcall+0x61/0xf0)
[ 2.525942] [<c0008745>] (do_one_initcall+0x61/0xf0) from [<c06836a1>] (kernel_init_freeable+0xbd/0x150)
[ 2.525961] [<c06836a1>] (kernel_init_freeable+0xbd/0x150) from [<c03dcf7b>] (kernel_init+0x7/0x90)
[ 2.525980] [<c03dcf7b>] (kernel_init+0x7/0x90) from [<c000c9bb>] (ret_from_fork+0x13/0x38)
[ 2.525986] ---[ end trace 45d9e9c5823d55ea ]---
[ 2.526002] [drm:drm_crtc_helper_set_config] *ERROR* failed to set mode on [CRTC:3]
[ 2.526016] fbcon_init: detected unhandled fb_set_par error, error code -22
是什么问题呢？
