From: Jonathan Liu <net147@gmail.com>
Date: Tue, 9 Jan 2018 13:03:23 +1100
Subject: drm/sun4i: hdmi: Add missing rate halving check in
sun4i_tmds_determine_rate
Git-commit: 3b9c57cef4de80f29885e1edf69828de8d3fae6b
Patch-mainline: v4.15-rc9
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
It was only checking the divider when determing the closest match if
it could not match the requested rate exactly.
For a projector connected to an Olimex A20-OLinuXino-LIME using HDMI
with a native resolution of 1280x800 and pixel clock of 83.5 MHz, this
resulted in 1280x800 mode not being available and the following in dmesg
when the kernel is booted with drm.debug=0x3e:
[drm:drm_mode_debug_printmodeline] Modeline 37:"1280x800" 60 83500 1280 1352 1480 1680 800 810 816 831 0x48 0x5
[drm:drm_mode_prune_invalid] Not using 1280x800 mode: NOCLOCK
Fixes: 9c5681011a0c ("drm/sun4i: Add HDMI support")
Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180109020323.11852-4-net147@gmail.com
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
@@ -102,9 +102,12 @@ static int sun4i_tmds_determine_rate(str
goto out;
}
- if (!best_parent || abs(rate - rounded / i) <
- abs(rate - best_parent / best_div)) {
+ if (!best_parent ||
+ abs(rate - rounded / i / j) <
+ abs(rate - best_parent / best_half /
+ best_div)) {
best_parent = rounded;
+ best_half = i;
best_div = j;
}
}