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[82.37.195.13]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42f7d353f8bsm4033746f8f.43.2025.12.04.08.17.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Dec 2025 08:17:22 -0800 (PST) Date: Thu, 4 Dec 2025 16:17:20 +0000 From: Daniel Thompson To: maudspierings@gocontroll.com Cc: Lee Jones , Daniel Thompson , Jingoo Han , Pavel Machek , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Helge Deller , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Liam Girdwood , Mark Brown , dri-devel@lists.freedesktop.org, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v6 2/4] backlight: add max25014atg backlight Message-ID: References: <20251201-max25014-v6-0-88e3ac8112ff@gocontroll.com> <20251201-max25014-v6-2-88e3ac8112ff@gocontroll.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251201-max25014-v6-2-88e3ac8112ff@gocontroll.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Dec 01, 2025 at 12:53:21PM +0100, Maud Spierings via B4 Relay wrote: > From: Maud Spierings > > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC > with integrated boost controller. > > Signed-off-by: Maud Spierings > > +static int max25014_check_errors(struct max25014 *maxim) > +{ > + uint32_t val; > + uint8_t i; > + int ret; > + > + ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val); > + if (ret) > + return ret; > + if (val) { > + dev_err(&maxim->client->dev, "Open led strings detected on:\n"); > + for (i = 0; i < 4; i++) { > + if (val & 1 << i) > + dev_err(&maxim->client->dev, "string %d\n", i + 1); > + } > + return -EIO; > + } > + > + ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val); > + if (ret) > + return ret; > + if (val) { > + dev_err(&maxim->client->dev, "Short to ground detected on:\n"); > + for (i = 0; i < 4; i++) { > + if (val & 1 << i) > + dev_err(&maxim->client->dev, "string %d\n", i + 1); > + } > + return -EIO; > + } > + > + ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val); Shouldn't this be MAX25014_SHORT_LED? > + if (ret) > + return ret; > + if (val) { > + dev_err(&maxim->client->dev, "Shorted led detected on:\n"); > + for (i = 0; i < 4; i++) { > + if (val & 1 << i) > + dev_err(&maxim->client->dev, "string %d\n", i + 1); > + } > + return -EIO; > + } > + > + ret = regmap_read(maxim->regmap, MAX25014_DIAG, &val); > + if (ret) > + return ret; > + /* > + * The HW_RST bit always starts at 1 after power up. > + * It is reset on first read, does not indicate an error. > + */ > + if (val && val != MAX25014_DIAG_HW_RST) { > + if (val & MAX25014_DIAG_OT) > + dev_err(&maxim->client->dev, > + "Overtemperature shutdown\n"); > + if (val & MAX25014_DIAG_OTW) > + dev_err(&maxim->client->dev, > + "Chip is getting too hot (>125C)\n"); > + if (val & MAX25014_DIAG_BSTOV) > + dev_err(&maxim->client->dev, > + "Boost converter overvoltage\n"); > + if (val & MAX25014_DIAG_BSTUV) > + dev_err(&maxim->client->dev, > + "Boost converter undervoltage\n"); > + if (val & MAX25014_DIAG_IREFOOR) > + dev_err(&maxim->client->dev, "IREF out of range\n"); > + return -EIO; > + } > + return 0; > +} > + > +/* > + * 1. disable unused strings > + * 2. set dim mode > + * 3. set setting register > + * 4. enable the backlight > + */ > +static int max25014_configure(struct max25014 *maxim, int initial_state) > +{ > + uint32_t val; > + int ret; > + > + /* > + * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if > + * it needs to be changed at all to prevent the backlight flashing when > + * it is configured correctly by the bootloader > + */ Attach the comment to the if statement rather than the read. > + ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val); > + if (ret) > + return ret; > + > + if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) { > + if (initial_state == BACKLIGHT_POWER_ON) { > + ret = regmap_write(maxim->regmap, MAX25014_ISET, 0); > + if (ret) > + return ret; > + } > + ret = regmap_write(maxim->regmap, MAX25014_DISABLE, maxim->strings_mask); > + if (ret) > + return ret; > + } > + > + ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM); > + if (ret) > + return ret; > + > + ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val); > + if (ret) > + return ret; > + > + ret = regmap_write(maxim->regmap, MAX25014_SETTING, > + val & ~MAX25014_SETTING_FPWM); > + if (ret) > + return ret; > + > + ret = regmap_write(maxim->regmap, MAX25014_ISET, > + maxim->iset | MAX25014_ISET_ENA | > + MAX25014_ISET_PSEN); > + return ret; > +} > + > +static int max25014_update_status(struct backlight_device *bl_dev) > +{ > + struct max25014 *maxim = bl_get_data(bl_dev); > + uint32_t reg; > + int ret; > + > + if (backlight_is_blank(maxim->bl)) > + bl_dev->props.brightness = 0; This isn't right. Why would you change the backlight level just because it is currently blanked (and sorry I missed this one last time). > + > + reg = TON_STEP * bl_dev->props.brightness; The correct way to honour blanking is just go call backlight_get_brightness() instead of reading the property directly. > + > + /* > + * 18 bit number lowest, 2 bits in first register, > + * next lowest 8 in the L register, next 8 in the H register > + * Seemingly setting the strength of only one string controls all of > + * them, individual settings don't affect the outcome. > + */ > + > + ret = regmap_write(maxim->regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011); > + if (ret != 0) > + return ret; > + ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111); > + if (ret != 0) > + return ret; > + return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111); > +} > + > +static const struct backlight_ops max25014_bl_ops = { > + .options = BL_CORE_SUSPENDRESUME, > + .update_status = max25014_update_status, > +}; > + > +static int max25014_parse_dt(struct max25014 *maxim, > + uint32_t *initial_brightness) > +{ > + struct device *dev = &maxim->client->dev; > + struct device_node *node = dev->of_node; > + struct fwnode_handle *child; > + uint32_t strings[4]; > + int res, i; > + > + if (!node) > + return dev_err_probe(dev, -EINVAL, "no platform data\n"); > + > + child = device_get_next_child_node(dev, NULL); > + if (child) { > + res = fwnode_property_count_u32(child, "led-sources"); > + if (res > 0) { > + fwnode_property_read_u32_array(child, "led-sources", > + strings, res); > + > + /* set all strings as disabled, then enable those in led-sources*/ > + maxim->strings_mask = 0xf; > + for (i = 0; i < res; i++) { > + if (strings[i] <= 4) > + maxim->strings_mask &= ~BIT(strings[i]); > + } > + } > + > + fwnode_property_read_u32(child, "default-brightness", > + initial_brightness); > + > + fwnode_handle_put(child); > + } > + > + maxim->iset = MAX25014_ISET_DEFAULT_100; > + of_property_read_u32(node, "maxim,iset", &maxim->iset); > + > + if (maxim->iset > 15) > + return dev_err_probe(dev, -EINVAL, > + "Invalid iset, should be a value from 0-15, entered was %d\n", > + maxim->iset); > + > + if (*initial_brightness > 100) > + return dev_err_probe(dev, -EINVAL, > + "Invalid initial brightness, should be a value from 0-100, entered was %d\n", > + *initial_brightness); > + > + return 0; > +} > + > +static int max25014_probe(struct i2c_client *cl) > +{ > + const struct i2c_device_id *id = i2c_client_get_device_id(cl); > + struct backlight_properties props; > + uint32_t initial_brightness = 50; > + struct backlight_device *bl; > + struct max25014 *maxim; > + int ret; > + > + maxim = devm_kzalloc(&cl->dev, sizeof(struct max25014), GFP_KERNEL); > + if (!maxim) > + return -ENOMEM; > + > + maxim->client = cl; > + > + ret = max25014_parse_dt(maxim, &initial_brightness); > + if (ret) > + return ret; > + > + maxim->vin = devm_regulator_get(&maxim->client->dev, "power"); > + if (IS_ERR(maxim->vin)) { > + return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->vin), > + "failed to get power-supply"); > + } > + > + ret = regulator_enable(maxim->vin); > + if (ret) > + return dev_err_probe(&maxim->client->dev, ret, > + "failed to enable power-supply\n"); Can this use devm_regulator_get_enable()? > + > + maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable", > + GPIOD_OUT_HIGH); > + if (IS_ERR(maxim->enable)) { > + ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable), > + "failed to get enable gpio\n"); > + goto disable_vin; > + } > + > + /* Datasheet Electrical Characteristics tSTARTUP 2ms */ > + fsleep(2000); > + > + maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config); > + if (IS_ERR(maxim->regmap)) { > + ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap), > + "failed to initialize the i2c regmap\n"); > + goto disable_full; > + } > + > + i2c_set_clientdata(cl, maxim); > + > + ret = max25014_check_errors(maxim); > + if (ret) { /* error is already reported in the above function */ > + goto disable_full; > + } > + > + ret = max25014_initial_power_state(maxim); > + if (ret < 0) { > + dev_err_probe(&maxim->client->dev, ret, "Could not get enabled state\n"); > + goto disable_full; > + } > + > + memset(&props, 0, sizeof(struct backlight_properties)); > + props.type = BACKLIGHT_PLATFORM; > + props.max_brightness = MAX_BRIGHTNESS; > + props.brightness = initial_brightness; > + props.scale = BACKLIGHT_SCALE_LINEAR; > + props.power = ret; > + > + ret = max25014_configure(maxim, ret); > + if (ret) { > + dev_err_probe(&maxim->client->dev, ret, "device config error"); > + goto disable_full; > + } > + > + bl = devm_backlight_device_register(&maxim->client->dev, id->name, > + &maxim->client->dev, maxim, > + &max25014_bl_ops, &props); > + if (IS_ERR(bl)) { > + ret = dev_err_probe(&maxim->client->dev, PTR_ERR(bl), > + "failed to register backlight\n"); > + goto disable_full; > + } > + > + maxim->bl = bl; > + > + backlight_update_status(maxim->bl); > + > + return 0; > + > +disable_full: > + gpiod_set_value_cansleep(maxim->enable, 0); Why is this needed? It was only ever set by devm_gpiod_get_optional(). > +disable_vin: > + regulator_disable(maxim->vin); This is also not needed if you use devm_regulator_get_enable(). > + return ret; > +} Daniel.