From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon@freedesktop.org Subject: [Bug 87682] Horizontal lines in radeon driver on kernel 3.15 and upwards Date: Tue, 10 May 2016 01:42:07 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1534797378==" Return-path: Received: from culpepper.freedesktop.org (culpepper.freedesktop.org [IPv6:2610:10:20:722:a800:ff:fe98:4b55]) by gabe.freedesktop.org (Postfix) with ESMTP id 4E2F76E573 for ; Tue, 10 May 2016 01:42:07 +0000 (UTC) In-Reply-To: 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 --===============1534797378== Content-Type: multipart/alternative; boundary="14628445273.3BEac.19366"; charset="UTF-8" --14628445273.3BEac.19366 Date: Tue, 10 May 2016 01:42:07 +0000 MIME-Version: 1.0 Content-Type: text/plain https://bugs.freedesktop.org/show_bug.cgi?id=87682 --- Comment #15 from Thom --- ok, i created a variation of the one liner patch that works without reverting any of the existing code: This patch prevents fb from going lower than 140 Preventing noise/snow on display . (for RS780M + LVDS) diff: @@ void radeon_compute_pll_avivo(struct radeon_pll *pll, /* determine allowed feedback divider range */ -- fb_div_min = pll->min_feedback_div; ++ fb_div_min = max(pll->min_feedback_div, 140u); fb_div_max = pll->max_feedback_div; if (pll->flags & RADEON_PLL_USE_FRAC_FB_DIV) { fb_div_min *= 10; results in: [drm:radeon_compute_pll_avivo] 69300 - 69290, pll dividers - fb: 271.0 ref: 4, post 14 This "works for me (TM)" But it would be good if someone could check if there are no "unforeseen consequences" to this patch. I don't know much about GPU stuff an I am not familiar with the code. (and yes I know: hardcoding values is definitely "not done") -- You are receiving this mail because: You are the assignee for the bug. --14628445273.3BEac.19366 Date: Tue, 10 May 2016 01:42:07 +0000 MIME-Version: 1.0 Content-Type: text/html

Comment # 15 on bug 87682 from 
ok, i created a variation of the one liner patch that works without reverting
any of the existing code:

    This patch prevents fb from going lower than 140
    Preventing noise/snow on display . (for RS780M + LVDS)

diff:
@@      void radeon_compute_pll_avivo(struct radeon_pll *pll,

    /* determine allowed feedback divider range */
--    fb_div_min = pll->min_feedback_div;
++    fb_div_min = max(pll->min_feedback_div, 140u);
    fb_div_max = pll->max_feedback_div;


     if (pll->flags & RADEON_PLL_USE_FRAC_FB_DIV) {
         fb_div_min *= 10;


results in:
[drm:radeon_compute_pll_avivo] 69300 - 69290, pll dividers - fb: 271.0 ref: 4,
post 14

This "works for me (TM)"

But it would be good if someone could check if there are no "unforeseen
consequences" to this patch.
I don't know much about GPU stuff an I am not familiar with the code.
(and yes I know: hardcoding values is definitely "not done")

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