Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   =?UTF-8?q?N=C3=ADcolas=20F=2E=20R=2E=20A=2E=20Prado?= 
        <nfraprado@collabora.com>
To:     Chun-Kuang Hu <chunkuang.hu@kernel.org>
Cc:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>, kernel@collabora.com,
        =?UTF-8?q?N=C3=ADcolas=20F=2E=20R=2E=20A=2E=20Prado?= 
        <nfraprado@collabora.com>, Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Jitao Shi <jitao.shi@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Rex-BC Chen <rex-bc.chen@mediatek.com>,
        Xinlei Lee <xinlei.lee@mediatek.com>,
        dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-mediatek@lists.infradead.org
Subject: [PATCH] drm/mediatek: dsi: Move mtk_dsi_stop() call back to mtk_dsi_poweroff()
Date:   Thu,  4 Aug 2022 15:43:25 -0400
Message-Id: <20220804194325.1596554-1-nfraprado@collabora.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

As the comment right before the mtk_dsi_stop() call advises,
mtk_dsi_stop() should only be called after
mtk_drm_crtc_atomic_disable(). That's because that function calls
drm_crtc_wait_one_vblank(), which requires the vblank irq to be enabled.

Previously mtk_dsi_stop(), being in mtk_dsi_poweroff() and guarded by a
refcount, would only be called at the end of
mtk_drm_crtc_atomic_disable(), through the call to mtk_crtc_ddp_hw_fini().
Commit cde7e2e35c28 ("drm/mediatek: Separate poweron/poweroff from
enable/disable and define new funcs") moved the mtk_dsi_stop() call to
mtk_output_dsi_disable(), causing it to be called before
mtk_drm_crtc_atomic_disable(), and consequently generating vblank
timeout warnings during suspend.

Move the mtk_dsi_stop() call back to mtk_dsi_poweroff() so that we have
a working vblank irq during mtk_drm_crtc_atomic_disable() and stop
getting vblank timeout warnings.

Fixes: cde7e2e35c28 ("drm/mediatek: Separate poweron/poweroff from enable/disable and define new funcs")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>

---

 drivers/gpu/drm/mediatek/mtk_dsi.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 9cc406e1eee1..f8ad59771551 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -685,6 +685,16 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
 	if (--dsi->refcount != 0)
 		return;
 
+	/*
+	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
+	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
+	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
+	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
+	 * after dsi is fully set.
+	 */
+	mtk_dsi_stop(dsi);
+
+	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
 	mtk_dsi_reset_engine(dsi);
 	mtk_dsi_lane0_ulp_mode_enter(dsi);
 	mtk_dsi_clk_ulp_mode_enter(dsi);
@@ -735,17 +745,6 @@ static void mtk_output_dsi_disable(struct mtk_dsi *dsi)
 	if (!dsi->enabled)
 		return;
 
-	/*
-	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
-	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
-	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
-	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
-	 * after dsi is fully set.
-	 */
-	mtk_dsi_stop(dsi);
-
-	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
-
 	dsi->enabled = false;
 }
 
-- 
2.37.1