From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon@freedesktop.org Subject: [Bug 91789] MST (multi stream) with Asus PQ321 drm_dp_calc_pbn_mode() fails Date: Fri, 28 Aug 2015 08:12:55 +0000 Message-ID: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1933034431==" Return-path: Received: from culpepper.freedesktop.org (unknown [131.252.210.165]) by gabe.freedesktop.org (Postfix) with ESMTP id 2C5956E1CD for ; Fri, 28 Aug 2015 01:12:55 -0700 (PDT) List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org --===============1933034431== Content-Type: multipart/alternative; boundary="1440749575.0575A0.27679"; charset="UTF-8" --1440749575.0575A0.27679 Date: Fri, 28 Aug 2015 08:12:55 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" https://bugs.freedesktop.org/show_bug.cgi?id=91789 Bug ID: 91789 Summary: MST (multi stream) with Asus PQ321 drm_dp_calc_pbn_mode() fails Product: DRI Version: unspecified Hardware: x86 (IA32) OS: Linux (All) Status: NEW Severity: normal Priority: medium Component: General Assignee: dri-devel@lists.freedesktop.org Reporter: Peter.Blum@lxco.com If a Asus monitor PQ321 is used in MST mode it gets no signal. This is because the function drm_dp_calc_pbn_mode() in drm_dp_mst_topology.c returns a bad pixel bandwith number for the mode Modeline 131:"1920x2160" 60 297000 1920 2008 2052 2200 2160 2168 2178 2250 0x48 0x5 The function return 8 and not the correct value of 1063. Using simple u32 arithmetic in drm_dp_calc_pbn_mode() the monitor works fine. I'm not sure if unsigned 32 bit would overflow in some cases. -- You are receiving this mail because: You are the assignee for the bug. --1440749575.0575A0.27679 Date: Fri, 28 Aug 2015 08:12:55 +0000 MIME-Version: 1.0 Content-Type: text/html; charset="UTF-8"
Bug ID 91789
Summary MST (multi stream) with Asus PQ321 drm_dp_calc_pbn_mode() fails
Product DRI
Version unspecified
Hardware x86 (IA32)
OS Linux (All)
Status NEW
Severity normal
Priority medium
Component General
Assignee dri-devel@lists.freedesktop.org
Reporter Peter.Blum@lxco.com 

If a Asus monitor PQ321 is used in MST mode it gets no signal.
This is because the function drm_dp_calc_pbn_mode() in drm_dp_mst_topology.c
returns a bad pixel bandwith number for the mode

Modeline 131:"1920x2160" 60 297000 1920 2008 2052 2200 2160 2168 2178 2250 0x48
0x5

The function return 8 and not the correct value of 1063.

Using simple u32 arithmetic in drm_dp_calc_pbn_mode() the monitor works fine.

I'm not sure if unsigned 32 bit would overflow in some cases.

You are receiving this mail because:
  • You are the assignee for the bug.
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