[PATCH 5.5 214/367] drm: atmel-hlcdc: prefer a lower pixel-clock than requested

Greg Kroah-Hartman
2020-02-10T12:45:18Z

From: Peter Rosin <peda@axentia.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@axentia.se>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Fixes: 9946a3a9dbed ("drm/atmel-hlcdc: allow selecting a higher pixel-clock than requested")
Reported-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Tested-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Cc: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: <stable@vger.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@linuxfoundation.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.