Input: matrix_keypad - check for errors from of_get_named_gpio()

"of_get_named_gpio()" returns a negative error value if it fails
and drivers should check for this. This missing check was now
added to the matrix_keypad driver.

In my case "of_get_named_gpio()" returned -EPROBE_DEFER because
the referenced GPIOs belong to an I/O expander, which was not yet
probed at the point in time when the matrix_keypad driver was
loading. Because the driver did not check for errors from the
"of_get_named_gpio()" routine, it was assuming that "-EPROBE_DEFER"
is actually a GPIO number and continued as usual, which led to further
errors like this later on:

WARNING: CPU: 3 PID: 167 at drivers/gpio/gpiolib.c:114
gpio_to_desc+0xc8/0xd0
invalid GPIO -517

Note that the "GPIO number" -517 in the error message above is
actually "-EPROBE_DEFER".

As part of the patch a misleading error message "no platform data defined"
was also removed. This does not lead to information loss because the other
error paths in matrix_keypad_parse_dt() already print an error.
Signed-off-by: Christian Hoff <christian_hoff@gmx.net>
Suggested-by: Sebastian Reichel <sre@kernel.org>
Reviewed-by: Sebastian Reichel <sre@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/matrix_keypad.c

@@ -407,7 +407,7 @@ matrix_keypad_parse_dt(struct device *dev)
 	struct matrix_keypad_platform_data *pdata;
 	struct device_node *np = dev->of_node;
 	unsigned int *gpios;
-	int i, nrow, ncol;
+	int ret, i, nrow, ncol;
 
 	if (!np) {
 		dev_err(dev, "device lacks DT data\n");
@@ -452,12 +452,19 @@ matrix_keypad_parse_dt(struct device *dev)
 		return ERR_PTR(-ENOMEM);
 	}
 
-	for (i = 0; i < pdata->num_row_gpios; i++)
-		gpios[i] = of_get_named_gpio(np, "row-gpios", i);
+	for (i = 0; i < nrow; i++) {
+		ret = of_get_named_gpio(np, "row-gpios", i);
+		if (ret < 0)
+			return ERR_PTR(ret);
+		gpios[i] = ret;
+	}
 
-	for (i = 0; i < pdata->num_col_gpios; i++)
-		gpios[pdata->num_row_gpios + i] =
-			of_get_named_gpio(np, "col-gpios", i);
+	for (i = 0; i < ncol; i++) {
+		ret = of_get_named_gpio(np, "col-gpios", i);
+		if (ret < 0)
+			return ERR_PTR(ret);
+		gpios[nrow + i] = ret;
+	}
 
 	pdata->row_gpios = gpios;
 	pdata->col_gpios = &gpios[pdata->num_row_gpios];
@@ -484,10 +491,8 @@ static int matrix_keypad_probe(struct platform_device *pdev)
 	pdata = dev_get_platdata(&pdev->dev);
 	if (!pdata) {
 		pdata = matrix_keypad_parse_dt(&pdev->dev);
-		if (IS_ERR(pdata)) {
-			dev_err(&pdev->dev, "no platform data defined\n");
+		if (IS_ERR(pdata))
 			return PTR_ERR(pdata);
-		}
 	} else if (!pdata->keymap_data) {
 		dev_err(&pdev->dev, "no keymap data defined\n");
 		return -EINVAL;