linux-kernel - [PATCH 5.7 192/393] drm/stm: repair runtime power management

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Date:   Mon, 17 Aug 2020 17:14:02 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marek Vasut <marex@...x.de>,
        Yannick Fertré <yannick.fertre@...com>,
        Philippe Cornu <philippe.cornu@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Vincent Abriou <vincent.abriou@...com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        Benjamin Gaignard <benjamin.gaignard@...com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 192/393] drm/stm: repair runtime power management

From: Marek Vasut <marex@...x.de>

[ Upstream commit ebd267b2e3c25d5f93a08528b47c036569eb8744 ]

Add missing pm_runtime_get_sync() into ltdc_crtc_atomic_enable() to
match pm_runtime_put_sync() in ltdc_crtc_atomic_disable(), otherwise
the LTDC might suspend via runtime PM, disable clock, and then fail
to resume later on.

The test which triggers it is roughly -- run qt5 application which
uses eglfs platform and etnaviv, stop the application, sleep for 15
minutes, run the application again. This leads to a timeout waiting
for vsync, because the LTDC has suspended, but did not resume.

Fixes: 35ab6cfbf211 ("drm/stm: support runtime power management")
Signed-off-by: Marek Vasut <marex@...x.de>
Cc: Yannick Fertré <yannick.fertre@...com>
Cc: Philippe Cornu <philippe.cornu@...com>
Cc: Benjamin Gaignard <benjamin.gaignard@...aro.org>
Cc: Vincent Abriou <vincent.abriou@...com>
Cc: Maxime Coquelin <mcoquelin.stm32@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...com>
To: dri-devel@...ts.freedesktop.org
Cc: linux-stm32@...md-mailman.stormreply.com
Cc: linux-arm-kernel@...ts.infradead.org
Acked-by: Philippe Cornu <philippe.cornu@...com>
Tested-by: Yannick Fertre <yannick.fertre@...com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200229221649.90813-1-marex@denx.de
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/stm/ltdc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index df585fe64f614..60ffe5bbc1294 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -425,9 +425,12 @@ static void ltdc_crtc_atomic_enable(struct drm_crtc *crtc,
 				    struct drm_crtc_state *old_state)
 {
 	struct ltdc_device *ldev = crtc_to_ltdc(crtc);
+	struct drm_device *ddev = crtc->dev;
 
 	DRM_DEBUG_DRIVER("\n");
 
+	pm_runtime_get_sync(ddev->dev);
+
 	/* Sets the background color value */
 	reg_write(ldev->regs, LTDC_BCCR, BCCR_BCBLACK);
 
-- 
2.25.1