Re: [PATCH v4 3/6] drm: Add driver for Solomon SSD130x OLED displays
flat view
From: Javier Martinez Canillas <javierm@redhat.com>
Date: 2022-02-11 12:06:09
Also in:
dri-devel, linux-pwm, lkml
On 2/11/22 12:33, Andy Shevchenko wrote:
On Fri, Feb 11, 2022 at 10:19:24AM +0100, Javier Martinez Canillas wrote:quoted
This adds a DRM driver for SSD1305, SSD1306, SSD1307 and SSD1309 Solomon OLED display controllers. It's only the core part of the driver and a bus specific driver is needed for each transport interface supported by the display controllers....quoted
+#include <linux/backlight.h> +#include <linux/bitfield.h>bits.h
Ok, missed that both weren't in the same macro.
(FYI, specifically sent a patch few days ago to add explicitly the inclusions that needed for bitfield operations in the example inside bitfield.h).quoted
+#include <linux/delay.h> +#include <linux/gpio/consumer.h> +#include <linux/property.h> +#include <linux/pwm.h> +#include <linux/regulator/consumer.h>...quoted
+#define SSD130X_SET_ADDRESS_MODE_HORIZONTAL (0x00) +#define SSD130X_SET_ADDRESS_MODE_VERTICAL (0x01) +#define SSD130X_SET_ADDRESS_MODE_PAGE (0x02) + +#define SSD130X_SET_AREA_COLOR_MODE_ENABLE (0x1e) +#define SSD130X_SET_AREA_COLOR_MODE_LOW_POWER (0x05)Do the parentheses add anything here?
Not really, the fbdev driver used it and I understood that was a convention to denote that these are command options and not a command or register. I'll drop them.
...quoted
+/* + * Helper to write command (SSD130X_COMMAND). The fist variadic argument + * is the command to write and the following are the command options.This is not correct explanation. Please, rephrase to show that _each_ of the options is sent with a preceding command.
It's a correct explanation IMO from the caller point of view. The first argument is the command sent (i.e: SSD130X_SET_ADDRESS_MODE) and the next ones are the the command options (i.e: SSD130X_SET_ADDRESS_MODE_HORIZONTAL). The fact that each command and options are preceding with a SSD130X_COMMAND value is part of the protocol of the device and a detail that's abstracted away by this helper function to the callers.
quoted
+ */ +static int ssd130x_write_cmd(struct ssd130x_device *ssd130x, int count, + /* u8 cmd, u8 option, ... */...) +{ + va_list ap; + u8 value; + int ret; + + va_start(ap, count); + + do { + value = va_arg(ap, int); + ret = regmap_write(ssd130x->regmap, SSD130X_COMMAND, (u8)value); + if (ret) + goto out_end; + } while (--count); + +out_end: + va_end(ap); + + return ret; +}...quoted
+ if (ssd130x->device_info->need_pwm) {Yeah, unfortunately we still don't have pwm_get_optional()...quoted
+ ret = ssd130x_pwm_enable(ssd130x); + if (ret) { + dev_err(dev, "Failed to enable PWM: %d\n", ret); + regulator_disable(ssd130x->vcc_reg); + return ret; + } + }...quoted
+static void ssd130x_power_off(struct ssd130x_device *ssd130x) +{quoted
+ if (ssd130x->device_info->need_pwm) {Redundant check. The two below are NULL-aware.
Ok, I'll drop it.
quoted
+ pwm_disable(ssd130x->pwm); + pwm_put(ssd130x->pwm); + } + + regulator_disable(ssd130x->vcc_reg); +}...quoted
+ ret = ssd130x_write_cmd(ssd130x, 2, SSD130X_SET_COM_PINS_CONFIG, compins); + if (ret < 0) + return ret;quoted
+ +One blank line is enough.
Indeed, that was a left over when changing this to use the macros.
...quoted
+ for (i = y / 8; i < y / 8 + pages; i++) { + int m = 8; + + /* Last page may be partial */ + if (8 * (i + 1) > ssd130x->height) + m = ssd130x->height % 8;Perhaps it can be moved out of the loop with refactored piece below.
Not sure I'm following since it depends on the for loop iterator value. [snip]
quoted
+ bl = devm_backlight_device_register(dev, dev_name(dev), dev, ssd130x, + &ssd130xfb_bl_ops, NULL); + if (IS_ERR(bl)) {quoted
+ ret = PTR_ERR(bl); + dev_err_probe(dev, ret, "Unable to register backlight device\n"); + return ERR_PTR(ret);dev_err_probe(dev, PTR_ERR(bl), "Unable to register backlight device\n"); return bl; ?
No, because this function's return value is a struct ssd130x_device pointer, not a struct backlight_device pointer. Best regards, -- Javier Martinez Canillas Linux Engineering Red Hat