linux-kernel - [PATCH] drm: hdlcd: Skip checking the clock provider when CRTC is disabled.

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Message-Id: <20171101141625.3297-1-Liviu.Dudau@arm.com>
Date:   Wed,  1 Nov 2017 14:16:25 +0000
From:   Liviu Dudau <Liviu.Dudau@....com>
To:     Brian Starkey <brian.starkey@....com>
Cc:     Mali DP Maintainers <malidp@...s.arm.com>,
        David Airlie <airlied@...ux.ie>,
        DRI-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] drm: hdlcd: Skip checking the clock provider when CRTC is disabled.

Some clock providers (clk-vexpress-osc) trigger a WARN() when the
requested rate falls outside its capabilities, as is the case when
a CRTC gets disabled. Check if the CRTC's new state is enabled and
skip the clk_round_rate() call if it is not.

Reported-by: Vladimir Murzin <vladimir.murzin@....com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
Tested-by: Vladimir Murzin <vladimir.murzin@....com>
---
 drivers/gpu/drm/arm/hdlcd_crtc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/arm/hdlcd_crtc.c b/drivers/gpu/drm/arm/hdlcd_crtc.c
index 72b22b805412b..a1387a8bf78c4 100644
--- a/drivers/gpu/drm/arm/hdlcd_crtc.c
+++ b/drivers/gpu/drm/arm/hdlcd_crtc.c
@@ -193,6 +193,10 @@ static int hdlcd_crtc_atomic_check(struct drm_crtc *crtc,
 	struct drm_display_mode *mode = &state->adjusted_mode;
 	long rate, clk_rate = mode->clock * 1000;
 
+	/* if the crtc is disabled, skip the clock check */
+	if (!state->enable)
+		return 0;
+
 	rate = clk_round_rate(hdlcd->clk, clk_rate);
 	if (rate != clk_rate) {
 		/* clock required by mode not supported by hardware */
-- 
2.14.1