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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Sebastian Reichel <sebastian.reichel@collabora.co.uk>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.14 454/496] drm: omapdrm: dss: Move initialization code from component bind to probe
Date:   Mon, 28 May 2018 12:03:59 +0200
Message-Id: <20180528100339.038756658@linuxfoundation.org>
In-Reply-To: <20180528100319.498712256@linuxfoundation.org>
References: <20180528100319.498712256@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

[ Upstream commit 215003b4ae1d47035092fef73b6a22aa82037091 ]

There's no reason to delay initialization of most of the driver (such as
mapping memory I/O, getting clocks or enabling runtime PM) to the
component master bind handler.

This additionally fixes a real PM issue caused enabling runtime PM in
the bind handler.

The bind handler performs the following sequence of PM operations:

	pm_runtime_enable(dev);
	pm_runtime_get_sync(dev);

	... (access the hardware to read the device revision) ...

	pm_runtime_put_sync(dev);

If a failure occurs at this point, the error path calls
pm_runtime_disable() to balance the pm_runtime_enable() call.

To understand the problem, it should be noted that the bind handler is
called when one of the component registers itself, which happens in the
component's probe handler. Furthermore, as the components are children
of the DSS, the device core calls pm_runtime_get_sync() on the DSS
platform device before calling the component's probe handler. This
increases the DSS power usage count but doesn't runtime resume the
device, as runtime PM is disabled at that point.

The bind handler is thus called with runtime PM disabled, with the
device runtime suspended, but with the power usage count larger than 0.
The pm_runtime_get_sync() call will thus further increase the power
usage count and runtime resume the device. The pm_runtime_put_sync()
handler will decrease the power usage count to a non-zero value and will
thus not suspend the device. Finally, the pm_runtime_disable() call will
disable runtime PM, preventing the pm_runtime_put() call in the device
core from runtime suspending the device. The DSS device is thus left
powered on.

To fix this, move the initialization code from the bind handler to the
probe handler.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/omapdrm/dss/dss.c |  193 ++++++++++++++++++++------------------
 1 file changed, 104 insertions(+), 89 deletions(-)

--- a/drivers/gpu/drm/omapdrm/dss/dss.c
+++ b/drivers/gpu/drm/omapdrm/dss/dss.c
@@ -1299,88 +1299,18 @@ static const struct soc_device_attribute
 
 static int dss_bind(struct device *dev)
 {
-	struct platform_device *pdev = to_platform_device(dev);
-	struct resource *dss_mem;
-	u32 rev;
 	int r;
 
-	dss_mem = platform_get_resource(dss.pdev, IORESOURCE_MEM, 0);
-	dss.base = devm_ioremap_resource(&pdev->dev, dss_mem);
-	if (IS_ERR(dss.base))
-		return PTR_ERR(dss.base);
-
-	r = dss_get_clocks();
+	r = component_bind_all(dev, NULL);
 	if (r)
 		return r;
 
-	r = dss_setup_default_clock();
-	if (r)
-		goto err_setup_clocks;
-
-	r = dss_video_pll_probe(pdev);
-	if (r)
-		goto err_pll_init;
-
-	r = dss_init_ports(pdev);
-	if (r)
-		goto err_init_ports;
-
-	pm_runtime_enable(&pdev->dev);
-
-	r = dss_runtime_get();
-	if (r)
-		goto err_runtime_get;
-
-	dss.dss_clk_rate = clk_get_rate(dss.dss_clk);
-
-	/* Select DPLL */
-	REG_FLD_MOD(DSS_CONTROL, 0, 0, 0);
-
-	dss_select_dispc_clk_source(DSS_CLK_SRC_FCK);
-
-#ifdef CONFIG_OMAP2_DSS_VENC
-	REG_FLD_MOD(DSS_CONTROL, 1, 4, 4);	/* venc dac demen */
-	REG_FLD_MOD(DSS_CONTROL, 1, 3, 3);	/* venc clock 4x enable */
-	REG_FLD_MOD(DSS_CONTROL, 0, 2, 2);	/* venc clock mode = normal */
-#endif
-	dss.dsi_clk_source[0] = DSS_CLK_SRC_FCK;
-	dss.dsi_clk_source[1] = DSS_CLK_SRC_FCK;
-	dss.dispc_clk_source = DSS_CLK_SRC_FCK;
-	dss.lcd_clk_source[0] = DSS_CLK_SRC_FCK;
-	dss.lcd_clk_source[1] = DSS_CLK_SRC_FCK;
-
-	rev = dss_read_reg(DSS_REVISION);
-	pr_info("OMAP DSS rev %d.%d\n", FLD_GET(rev, 7, 4), FLD_GET(rev, 3, 0));
-
-	dss_runtime_put();
-
-	r = component_bind_all(&pdev->dev, NULL);
-	if (r)
-		goto err_component;
-
-	dss_debugfs_create_file("dss", dss_dump_regs);
-
 	pm_set_vt_switch(0);
 
 	omapdss_gather_components(dev);
 	omapdss_set_is_initialized(true);
 
 	return 0;
-
-err_component:
-err_runtime_get:
-	pm_runtime_disable(&pdev->dev);
-	dss_uninit_ports(pdev);
-err_init_ports:
-	if (dss.video1_pll)
-		dss_video_pll_uninit(dss.video1_pll);
-
-	if (dss.video2_pll)
-		dss_video_pll_uninit(dss.video2_pll);
-err_pll_init:
-err_setup_clocks:
-	dss_put_clocks();
-	return r;
 }
 
 static void dss_unbind(struct device *dev)
@@ -1390,18 +1320,6 @@ static void dss_unbind(struct device *de
 	omapdss_set_is_initialized(false);
 
 	component_unbind_all(&pdev->dev, NULL);
-
-	if (dss.video1_pll)
-		dss_video_pll_uninit(dss.video1_pll);
-
-	if (dss.video2_pll)
-		dss_video_pll_uninit(dss.video2_pll);
-
-	dss_uninit_ports(pdev);
-
-	pm_runtime_disable(&pdev->dev);
-
-	dss_put_clocks();
 }
 
 static const struct component_master_ops dss_component_ops = {
@@ -1433,10 +1351,46 @@ static int dss_add_child_component(struc
 	return 0;
 }
 
+static int dss_probe_hardware(void)
+{
+	u32 rev;
+	int r;
+
+	r = dss_runtime_get();
+	if (r)
+		return r;
+
+	dss.dss_clk_rate = clk_get_rate(dss.dss_clk);
+
+	/* Select DPLL */
+	REG_FLD_MOD(DSS_CONTROL, 0, 0, 0);
+
+	dss_select_dispc_clk_source(DSS_CLK_SRC_FCK);
+
+#ifdef CONFIG_OMAP2_DSS_VENC
+	REG_FLD_MOD(DSS_CONTROL, 1, 4, 4);	/* venc dac demen */
+	REG_FLD_MOD(DSS_CONTROL, 1, 3, 3);	/* venc clock 4x enable */
+	REG_FLD_MOD(DSS_CONTROL, 0, 2, 2);	/* venc clock mode = normal */
+#endif
+	dss.dsi_clk_source[0] = DSS_CLK_SRC_FCK;
+	dss.dsi_clk_source[1] = DSS_CLK_SRC_FCK;
+	dss.dispc_clk_source = DSS_CLK_SRC_FCK;
+	dss.lcd_clk_source[0] = DSS_CLK_SRC_FCK;
+	dss.lcd_clk_source[1] = DSS_CLK_SRC_FCK;
+
+	rev = dss_read_reg(DSS_REVISION);
+	pr_info("OMAP DSS rev %d.%d\n", FLD_GET(rev, 7, 4), FLD_GET(rev, 3, 0));
+
+	dss_runtime_put();
+
+	return 0;
+}
+
 static int dss_probe(struct platform_device *pdev)
 {
 	const struct soc_device_attribute *soc;
 	struct component_match *match = NULL;
+	struct resource *dss_mem;
 	int r;
 
 	dss.pdev = pdev;
@@ -1451,20 +1405,69 @@ static int dss_probe(struct platform_dev
 	else
 		dss.feat = of_match_device(dss_of_match, &pdev->dev)->data;
 
-	r = dss_initialize_debugfs();
+	/* Map I/O registers, get and setup clocks. */
+	dss_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dss.base = devm_ioremap_resource(&pdev->dev, dss_mem);
+	if (IS_ERR(dss.base))
+		return PTR_ERR(dss.base);
+
+	r = dss_get_clocks();
 	if (r)
 		return r;
 
-	/* add all the child devices as components */
+	r = dss_setup_default_clock();
+	if (r)
+		goto err_put_clocks;
+
+	/* Setup the video PLLs and the DPI and SDI ports. */
+	r = dss_video_pll_probe(pdev);
+	if (r)
+		goto err_put_clocks;
+
+	r = dss_init_ports(pdev);
+	if (r)
+		goto err_uninit_plls;
+
+	/* Enable runtime PM and probe the hardware. */
+	pm_runtime_enable(&pdev->dev);
+
+	r = dss_probe_hardware();
+	if (r)
+		goto err_pm_runtime_disable;
+
+	/* Initialize debugfs. */
+	r = dss_initialize_debugfs();
+	if (r)
+		goto err_pm_runtime_disable;
+
+	dss_debugfs_create_file("dss", dss_dump_regs);
+
+	/* Add all the child devices as components. */
 	device_for_each_child(&pdev->dev, &match, dss_add_child_component);
 
 	r = component_master_add_with_match(&pdev->dev, &dss_component_ops, match);
-	if (r) {
-		dss_uninitialize_debugfs();
-		return r;
-	}
+	if (r)
+		goto err_uninit_debugfs;
 
 	return 0;
+
+err_uninit_debugfs:
+	dss_uninitialize_debugfs();
+
+err_pm_runtime_disable:
+	pm_runtime_disable(&pdev->dev);
+	dss_uninit_ports(pdev);
+
+err_uninit_plls:
+	if (dss.video1_pll)
+		dss_video_pll_uninit(dss.video1_pll);
+	if (dss.video2_pll)
+		dss_video_pll_uninit(dss.video2_pll);
+
+err_put_clocks:
+	dss_put_clocks();
+
+	return r;
 }
 
 static int dss_remove(struct platform_device *pdev)
@@ -1473,6 +1476,18 @@ static int dss_remove(struct platform_de
 
 	dss_uninitialize_debugfs();
 
+	pm_runtime_disable(&pdev->dev);
+
+	dss_uninit_ports(pdev);
+
+	if (dss.video1_pll)
+		dss_video_pll_uninit(dss.video1_pll);
+
+	if (dss.video2_pll)
+		dss_video_pll_uninit(dss.video2_pll);
+
+	dss_put_clocks();
+
 	return 0;
 }