On Wed, Aug 20, 2014 at 06:03:52PM +0000, Wilde, Martin wrote: > Hi Jani - the DRM_DEBUG_KMS is part of the DRM_DEBUG_CODE preprocessor > macro and thus not available unavailable in a non-debug build kernel from > my understanding. > > The issue we have seen many times is that the BIOS (firmware) team does > not set the T3 value correctly in the VBT table of the BIOS (or they use > the VESA default of 200ms and the panel is really a 50ms panel) and thus > there is no way to quickly determine what value was set unless you build a > debug kernel version that is typically beyond the scope of the BIOS team > (we have also had problems tracking down who in the BIOS team made the > setting). For example in the latest Coreboot firmware for Rambi > Chromebook, someone set the VBT T3 value to 500 instead of 200. This was > not detected until I ran the S3 resume test and noticed the S3 resume time > was 300ms too long. Having the INFO message available in dmesg output > allowed me to quickly see the value was set wrong and address it without > having to do a debug build or do debugging to find the issue. Additionally > having the INFO message can be used by the firmware team to verify their > setting is correct. We are also asking the Windows Gfx driver to do the > same as it happens more frequently than we thought. Until we have fully > implemented HDP detection in the drivers, this issue will continue > happening. > > So the request is to expose this as an INFO message to allow quick > detection/verification of correct setting as VBT settings can be set > in-correctly in a firmware update and not easily detected without special > kernel builds. This allows the QA team to track platform settings that > effect the responsive time of mobile platforms. > > Let me know if you have further questions and thanks for feedback I would suggest a /debugfs/.../i915_panel_capabilities and/or i915_vbt_capabilites. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
