Hello, I'm writing you to get more info about a possible bug we are experiencing on kernel 4.9 (details below). If this is not the proper address please accept my apologies and let me know where I should address my request to. We are running Linux on a EMX-SKLUP machine (https://www.avalue.com.tw/Product/Industrial-PC/Industrial-Motherboard/Thin-Mini-ITX/EMX-SKLUP_2521 ) This machine mounts a graphics card: Intel® Skylake U SoC integrated Graphics and we are using the i915 driver to drive two screens, one using the HDMI port and the other using the DisplayPort. We tried different kernels and we noticed the following:
1. Kernel 4.4 --> all versions work like a charm 2. Kernel 4.9 --> all versions before 4.9.30 work. All versions after 4.9.40 have problem with the HDMI port. It simply turns out to be always disconnected when issuing an xrandr. Thus, the screen is simply blank. The DisplayPort connection works perfectly. We made some narrowing and the problem seems to have been introduced between the following two commits: · 4.9.30 commit: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-4.9.y&id=db3fd4527ed32be44cbd8ffa6dd6a301c89d0d6d · 4.9.40 commit: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-4.9.y&id=efcfbfb1d8bf756d1b58fe215bf4e419d176435b · diff of i915 dir: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/diff/drivers/gpu/drm/i915?h=linux-4.9.y&id=db3fd4527ed32be44cbd8ffa6dd6a301c89d0d6d&id2=efcfbfb1d8bf756d1b58fe215bf4e419d176435b 3. All following kernels have the same problem. I attach some info to the present email and I am at your disposal for any additional info you may need. I thank you for any insight you can provide us to solve this issue. Thanks a lot, Enrico Deotto Firmware and Software Manager GDS / Global Display Solutions Spa Via Tezze, 20/A - 36073 Cornedo (VI) ITALY [cid:image002.png@01D1A7BF.B77C8C00]Italy M: +39 3920961186 E. e.deo...@gds.com<mailto:e.deo...@gds.com> W. http://displays.gds.com/<https://urldefense.proofpoint.com/v2/url?u=http-3A__displays.gds.com_&d=DwMFAw&c=GC0NZZhaEw6GOQSjMHI2g15k_drElRoPmOYiK2k0eZ8&r=uepINBU0Dj9IbNKNiA2gpkiuxLsRtZW-KkjUkUzxecQ&m=LshAfsGbvQNY-xYOGLqa99HflhcvC5s9XwjPknKmSfI&s=5p0k7w1gRCODUVp1OOdX-M4sPoCWikJ6UhL-tZYubzw&e=>
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