linux-kernel - [PATCH v2 4/4] drm/tegra: Use dev_err

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Message-Id: <20211130230957.30213-5-digetx@gmail.com>
Date:   Wed,  1 Dec 2021 02:09:57 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Lyude Paul <lyude@...hat.com>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Thomas Graichen <thomas.graichen@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/4] drm/tegra: Use dev_err_probe()

Replace dev_printk() with a generic dev_err_probe() helper which silences
noisy error messages about deferred probe and makes easy to debug failing
deferred probe by printing notification about the failure to KMSG in the
end of kernel booting process and by adding failing device and the reason
of deferred probe to devices_deferred of debugfs. This was proven to be
useful in the case of eDP driver regression by immediately showing why
display driver was failing when user asked for help, otherwise it would've
been much more difficult to debug such problems on a third party device
that doesn't have developer setup.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/gpu/drm/tegra/dc.c   | 13 +++----------
 drivers/gpu/drm/tegra/hdmi.c | 34 +++++++++-------------------------
 2 files changed, 12 insertions(+), 35 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 7ea3c045a6f7..f7370d28816f 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -3236,16 +3236,9 @@ static int tegra_dc_probe(struct platform_device *pdev)
 		return -ENXIO;
 
 	err = tegra_dc_rgb_probe(dc);
-	if (err < 0 && err != -ENODEV) {
-		const char *level = KERN_ERR;
-
-		if (err == -EPROBE_DEFER)
-			level = KERN_DEBUG;
-
-		dev_printk(level, dc->dev, "failed to probe RGB output: %d\n",
-			   err);
-		return err;
-	}
+	if (err < 0 && err != -ENODEV)
+		return dev_err_probe(&pdev->dev, err,
+				     "failed to probe RGB output\n");
 
 	platform_set_drvdata(pdev, dc);
 	pm_runtime_enable(&pdev->dev);
diff --git a/drivers/gpu/drm/tegra/hdmi.c b/drivers/gpu/drm/tegra/hdmi.c
index 9a87d351a828..3242baddc5e7 100644
--- a/drivers/gpu/drm/tegra/hdmi.c
+++ b/drivers/gpu/drm/tegra/hdmi.c
@@ -1638,7 +1638,6 @@ static irqreturn_t tegra_hdmi_irq(int irq, void *data)
 
 static int tegra_hdmi_probe(struct platform_device *pdev)
 {
-	const char *level = KERN_ERR;
 	struct tegra_hdmi *hdmi;
 	struct resource *regs;
 	int err;
@@ -1678,36 +1677,21 @@ static int tegra_hdmi_probe(struct platform_device *pdev)
 
 	hdmi->hdmi = devm_regulator_get(&pdev->dev, "hdmi");
 	err = PTR_ERR_OR_ZERO(hdmi->hdmi);
-	if (err) {
-		if (err == -EPROBE_DEFER)
-			level = KERN_DEBUG;
-
-		dev_printk(level, &pdev->dev,
-			   "failed to get HDMI regulator: %d\n", err);
-		return err;
-	}
+	if (err)
+		return dev_err_probe(&pdev->dev, err,
+				     "failed to get HDMI regulator\n");
 
 	hdmi->pll = devm_regulator_get(&pdev->dev, "pll");
 	err = PTR_ERR_OR_ZERO(hdmi->pll);
-	if (err) {
-		if (err == -EPROBE_DEFER)
-			level = KERN_DEBUG;
-
-		dev_printk(level, &pdev->dev,
-			   "failed to get PLL regulator: %d\n", err);
-		return err;
-	}
+	if (err)
+		return dev_err_probe(&pdev->dev, err,
+				     "failed to get PLL regulator\n");
 
 	hdmi->vdd = devm_regulator_get(&pdev->dev, "vdd");
 	err = PTR_ERR_OR_ZERO(hdmi->vdd);
-	if (err) {
-		if (err == -EPROBE_DEFER)
-			level = KERN_DEBUG;
-
-		dev_printk(level, &pdev->dev,
-			   "failed to get VDD regulator: %d\n", err);
-		return err;
-	}
+	if (err)
+		return dev_err_probe(&pdev->dev, err,
+				     "failed to get VDD regulator\n");
 
 	hdmi->output.dev = &pdev->dev;
 
-- 
2.33.1