From mboxrd@z Thu Jan 1 00:00:00 1970 From: net147@gmail.com (Jonathan Liu) Date: Tue, 9 Jan 2018 13:03:21 +1100 Subject: [PATCH v3 1/3] drm/sun4i: hdmi: Check for unset best_parent in sun4i_tmds_determine_rate In-Reply-To: <20180109020323.11852-1-net147@gmail.com> References: <20180109020323.11852-1-net147@gmail.com> Message-ID: <20180109020323.11852-2-net147@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 --- 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; -- 2.15.1