From 926a299c42e38bbe8bb909eae0146e676b66afe4 Mon Sep 17 00:00:00 2001 From: Russell King Date: Thu, 2 Aug 2018 10:27:15 +0100 Subject: [PATCH] drm/i2c: tda998x: correct PLL divider calculation The serializer PLL divider is a power-of-two divider, so our calculation which assumes that it's a numerical divider is incorrect. Replace it with one that results in a power-of-two divider value instead. Tested with all supported modes with a Samsung S24C750. Tested-by: Peter Rosin Signed-off-by: Russell King --- drivers/gpu/drm/i2c/tda998x_drv.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c index 7313ff8..0df86e9 100644 --- a/drivers/gpu/drm/i2c/tda998x_drv.c +++ b/drivers/gpu/drm/i2c/tda998x_drv.c @@ -1343,6 +1343,7 @@ static void tda998x_bridge_mode_set(struct drm_bridge *bridge, struct drm_display_mode *adjusted_mode) { struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge); + unsigned long tmds_clock; u16 ref_pix, ref_line, n_pix, n_line; u16 hs_pix_s, hs_pix_e; u16 vs1_pix_s, vs1_pix_e, vs1_line_s, vs1_line_e; @@ -1413,12 +1414,19 @@ static void tda998x_bridge_mode_set(struct drm_bridge *bridge, (mode->vsync_end - mode->vsync_start)/2; } - div = 148500 / mode->clock; - if (div != 0) { - div--; - if (div > 3) - div = 3; - } + tmds_clock = mode->clock; + + /* + * The divisor is power-of-2. The TDA9983B datasheet gives + * this as ranges of Msample/s, which is 10x the TMDS clock: + * 0 - 800 to 1500 Msample/s + * 1 - 400 to 800 Msample/s + * 2 - 200 to 400 Msample/s + * 3 - as 2 above + */ + for (div = 0; div < 3; div++) + if (80000 >> div <= tmds_clock) + break; mutex_lock(&priv->audio_mutex); -- 2.7.4