linux-kernel - [PATCH] drm/rockchip: vop: Add timeout for DSP hold

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Message-Id: <20211008153102.1.I2a5dbaaada35023a9703a8db7af501528fbb6e31@changeid>
Date:   Fri,  8 Oct 2021 15:31:04 -0700
From:   Brian Norris <briannorris@...omium.org>
To:     Heiko Stübner <heiko@...ech.de>
Cc:     linux-rockchip@...ts.infradead.org,
        Sandy Huang <hjc@...k-chips.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Brian Norris <briannorris@...omium.org>
Subject: [PATCH] drm/rockchip: vop: Add timeout for DSP hold

If hardware is malfunctioning (e.g., misconfigured clocks?), we can get
stuck here forever, holding various DRM locks and eventually locking up
the entire system. It's better to complain loudly and move on, than to
lock up the system.

In local tests, this operation takes less than 20ms.

Signed-off-by: Brian Norris <briannorris@...omium.org>
---

 drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index ba9e14da41b4..b28ea5d6a3e2 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -726,7 +726,9 @@ static void vop_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	spin_unlock(&vop->reg_lock);
 
-	wait_for_completion(&vop->dsp_hold_completion);
+	if (!wait_for_completion_timeout(&vop->dsp_hold_completion,
+					 msecs_to_jiffies(200)))
+		WARN(1, "%s: timed out waiting for DSP hold", crtc->name);
 
 	vop_dsp_hold_valid_irq_disable(vop);
 
-- 
2.33.0.882.g93a45727a2-goog