linux-kernel - [PATCH v2 5/6] drm: atmel-hlcdc: prefer a lower pixel-clock than requested

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Date:   Fri, 13 Dec 2019 17:04:55 +0200
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <sam@...nborg.org>, <bbrezillon@...nel.org>, <airlied@...ux.ie>,
        <daniel@...ll.ch>, <nicolas.ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <ludovic.desroches@...rochip.com>,
        <lee.jones@...aro.org>
CC:     <dri-devel@...ts.freedesktop.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Peter Rosin <peda@...ntia.se>
Subject: [PATCH v2 5/6] drm: atmel-hlcdc: prefer a lower pixel-clock than requested

From: Peter Rosin <peda@...ntia.se>

The intention was to only select a higher pixel-clock rate than the
requested, if a slight overclocking would result in a rate significantly
closer to the requested rate than if the conservative lower pixel-clock
rate is selected. The fixed patch has the logic the other way around and
actually prefers the higher frequency. Fix that.

Fixes: f6f7ad323461 ("drm/atmel-hlcdc: allow selecting a higher pixel-clock than requested")
Reported-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
Tested-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
Signed-off-by: Peter Rosin <peda@...ntia.se>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index 721fa88bf71d..10985134ce0b 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -121,8 +121,8 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
 		int div_low = prate / mode_rate;
 
 		if (div_low >= 2 &&
-		    ((prate / div_low - mode_rate) <
-		     10 * (mode_rate - prate / div)))
+		    (10 * (prate / div_low - mode_rate) <
+		     (mode_rate - prate / div)))
 			/*
 			 * At least 10 times better when using a higher
 			 * frequency than requested, instead of a lower.
-- 
2.7.4