linux-kernel - [PATCH] drm/sharp-memory: Fix IS_ERR() vs NULL check in sharp_memory

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Message-Id: <20260130092300.3426214-1-nichen@iscas.ac.cn>
Date: Fri, 30 Jan 2026 17:22:59 +0800
From: Chen Ni <nichen@...as.ac.cn>
To: lanzano.alex@...il.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	lumag@...nel.org,
	mehdi.djait@...tlin.com,
	u.kleine-koenig@...libre.com
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Chen Ni <nichen@...as.ac.cn>
Subject: [PATCH] drm/sharp-memory: Fix IS_ERR() vs NULL check in sharp_memory_probe()

The devm_drm_dev_alloc() function returns an ERR_PTR encoded error
pointer on failure, not NULL. devm_gpiod_get_optional() may return
ERR_PTR in case of genuine GPIO acquisition errors, not just NULL which
indicates the legitimate absence of an optional GPIO.

Replace the NULL check after devm_drm_dev_alloc() with IS_ERR() and add
a missing IS_ERR() check after devm_gpiod_get_optional(). On error,
return the error code from the probe function to ensure proper failure
handling rather than proceeding with invalid pointers.

Fixes: b8f9f21716fe ("drm/tiny: Add driver for Sharp Memory LCD")
Signed-off-by: Chen Ni <nichen@...as.ac.cn>
---
 drivers/gpu/drm/tiny/sharp-memory.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tiny/sharp-memory.c b/drivers/gpu/drm/tiny/sharp-memory.c
index 64272cd0f6e2..5e6a54a0696c 100644
--- a/drivers/gpu/drm/tiny/sharp-memory.c
+++ b/drivers/gpu/drm/tiny/sharp-memory.c
@@ -541,8 +541,9 @@ static int sharp_memory_probe(struct spi_device *spi)
 
 	smd = devm_drm_dev_alloc(dev, &sharp_memory_drm_driver,
 				 struct sharp_memory_device, drm);
-	if (!smd)
-		return -ENOMEM;
+	if (IS_ERR(smd))
+		return dev_err_probe(dev, PTR_ERR(smd),
+				     "Failed to allocate drm device\n");
 
 	spi_set_drvdata(spi, smd);
 
@@ -553,6 +554,9 @@ static int sharp_memory_probe(struct spi_device *spi)
 		return dev_err_probe(dev, ret, "Failed to initialize drm config\n");
 
 	smd->enable_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH);
+	if (IS_ERR(smd->enable_gpio))
+		return dev_err_probe(dev, PTR_ERR(smd->enable_gpio),
+				     "Failed to get gpio 'enable'\n");
 	if (!smd->enable_gpio)
 		dev_warn(dev, "Enable gpio not defined\n");
 
-- 
2.25.1