[bug report] backlight: hx8357: Convert to agnostic GPIO API

[Dan Carpenter]

Hello Andy Shevchenko,

The patch 7d84a63a39b7: "backlight: hx8357: Convert to agnostic GPIO
API" from Dec 7, 2023 (linux-next), leads to the following Smatch
static checker warning:

	drivers/video/backlight/hx8357.c:612 hx8357_probe()
	error: potential NULL/IS_ERR bug 'lcd->im_pins'

drivers/video/backlight/hx8357.c
    580 static int hx8357_probe(struct spi_device *spi)
    581 {
    582         struct device *dev = &spi->dev;
    583         struct lcd_device *lcdev;
    584         struct hx8357_data *lcd;
    585         const struct of_device_id *match;
    586         int i, ret;
    587 
    588         lcd = devm_kzalloc(&spi->dev, sizeof(*lcd), GFP_KERNEL);
    589         if (!lcd)
    590                 return -ENOMEM;
    591 
    592         ret = spi_setup(spi);
    593         if (ret < 0) {
    594                 dev_err(&spi->dev, "SPI setup failed.\n");
    595                 return ret;
    596         }
    597 
    598         lcd->spi = spi;
    599 
    600         match = of_match_device(hx8357_dt_ids, &spi->dev);
    601         if (!match || !match->data)
    602                 return -EINVAL;
    603 
    604         lcd->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
    605         if (IS_ERR(lcd->reset))
    606                 return dev_err_probe(dev, PTR_ERR(lcd->reset), "failed to request reset GPIO\n");
    607         gpiod_set_consumer_name(lcd->reset, "hx8357-reset");
    608 
    609         lcd->im_pins = devm_gpiod_get_array_optional(dev, "im", GPIOD_OUT_LOW);
    610         if (IS_ERR(lcd->im_pins))
    611                 return dev_err_probe(dev, PTR_ERR(lcd->im_pins), "failed to request im GPIOs\n");
--> 612         if (lcd->im_pins->ndescs < HX8357_NUM_IM_PINS)
                    ^^^^^^^^^^^^
I think _optional() functions can return NULL.

    613                 return dev_err_probe(dev, -EINVAL, "not enough im GPIOs\n");
    614 
    615         for (i = 0; i < HX8357_NUM_IM_PINS; i++)
    616                 gpiod_set_consumer_name(lcd->im_pins->desc[i], "im_pins");
    617 
    618         lcdev = devm_lcd_device_register(&spi->dev, "mxsfb", &spi->dev, lcd,
    619                                         &hx8357_ops);
    620         if (IS_ERR(lcdev)) {
    621                 ret = PTR_ERR(lcdev);
    622                 return ret;
    623         }
    624         spi_set_drvdata(spi, lcdev);
    625 
    626         hx8357_lcd_reset(lcdev);
    627 
    628         ret = ((int (*)(struct lcd_device *))match->data)(lcdev);
    629         if (ret) {
    630                 dev_err(&spi->dev, "Couldn't initialize panel\n");
    631                 return ret;
    632         }
    633 
    634         dev_info(&spi->dev, "Panel probed\n");
    635 
    636         return 0;
    637 }

regards,
dan carpenter