linux-kernel - [PATCH 5.4 188/309] drm: atmel-hlcdc: prefer a lower pixel-clock than requested

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Date:   Mon, 10 Feb 2020 04:32:24 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Peter Rosin <peda@...ntia.se>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Boris Brezillon <boris.brezillon@...tlin.com>
Subject: [PATCH 5.4 188/309] drm: atmel-hlcdc: prefer a lower pixel-clock than requested

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

commit 51a19d150b520f6cb42143f3bdffacd3c33d7ac5 upstream.

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.

Signed-off-by: Peter Rosin <peda@...ntia.se>
Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
Signed-off-by: Sam Ravnborg <sam@...nborg.org>
Fixes: 9946a3a9dbed ("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>
Cc: Boris Brezillon <boris.brezillon@...tlin.com>
Cc: <stable@...r.kernel.org> # v4.20+
Link: https://patchwork.freedesktop.org/patch/msgid/1576672109-22707-6-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- 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_no
 		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.