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drm/sun4i: hdmi: Add missing rate halving check in sun4i_tmds_determine_rate 

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: 9c5681011a ("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
This commit is contained in:
Jonathan Liu 2018-01-09 13:03:23 +11:00 committed by Maxime Ripard
parent 58faae28f6
commit 3b9c57cef4
1 changed files with 5 additions and 2 deletions
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7
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
View File

@ -102,9 +102,12 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw,
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;
}
}