It is possible that if there is no exact rate match and "rounded = clk_hw_round_rate(parent, ideal)" gives high enough values (e.g. if rounded is 2 * ideal) that the condition "abs(rate - rounded / i) < abs(rate - best_parent / best_div)" is never met and best_parent is never set. This results in req->rate and req->best_parent_rate being assigned 0.

To avoid this, we set best_parent to the first calculated rate if it is unset. The sun4i_tmds_calc_divider function already has a similar check.

Fixes: 9c5681011a0c ("drm/sun4i: Add HDMI support") Signed-off-by: Jonathan Liu net147@gmail.com --- drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c index dc332ea56f6c..4d235e5ea31c 100644 --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c @@ -102,7 +102,7 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw, goto out; }

- if (abs(rate - rounded / i) < + if (!best_parent || abs(rate - rounded / i) < abs(rate - best_parent / best_div)) { best_parent = rounded; best_div = i;

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 --- drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c index 88eeeaf34638..3ecffa52c814 100644 --- 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(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; } }