On Wed, Feb 09, 2022 at 10:03:10AM +0100, Javier Martinez Canillas wrote: > 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. Thank you for the update, my comments below. ... > source "drivers/gpu/drm/sprd/Kconfig" > > +source "drivers/gpu/drm/solomon/Kconfig" 'o' before 'p' ? ... > obj-$(CONFIG_DRM_SPRD) += sprd/ > +obj-y += solomon/ Ditto ? ... > +/* > + * DRM driver for Solomon SSD130X OLED displays Solomon SSD130x (with lower letter it's easy to read and realize that it's not a model name). > + * Copyright 2022 Red Hat Inc. > + * Authors: Javier Martinez Canillas <javierm@xxxxxxxxxx> > + * > + * Based on drivers/video/fbdev/ssd1307fb.c > + * Copyright 2012 Free Electrons > + */ > +#include <linux/backlight.h> > +#include <linux/delay.h> > +#include <linux/gpio/consumer.h> > +#include <linux/property.h> > +#include <linux/pwm.h> > +#include <linux/regulator/consumer.h> ... > +#define DRIVER_NAME "ssd130x" > +#define DRIVER_DESC "DRM driver for Solomon SSD130X OLED displays" > +#define DRIVER_DATE "20220131" > +#define DRIVER_MAJOR 1 > +#define DRIVER_MINOR 0 Not sure it has a value when being defined. Only one string is reused and even if hard coded twice linker will optimize it. ... > +/* > + * Helper to write command (SSD130X_COMMAND). The fist variadic argument > + * is the command to write and the following are the command options. > + */ > +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; Can bulk operation be used in the callers instead? I have noticed that all of the callers are using - 1 -- makes no sense at all, can be replaced with regmap_write() - 2 - 3 Can be helpers for two and three arguments, with use of bulk call. What do you think? > +} ... > +static void ssd130x_reset(struct ssd130x_device *ssd130x) > +{ > + /* Reset the screen */ > + gpiod_set_value_cansleep(ssd130x->reset, 1); > + udelay(4); > + gpiod_set_value_cansleep(ssd130x->reset, 0); > + udelay(4); I don't remember if reset pin is mandatory. fbtft does if (!gpiod->reset) return; ...do reset... > +} ... > + if (ssd130x->reset) A-ha, why not in the callee? > + ssd130x_reset(ssd130x); ... > + /* Set COM direction */ > + com_invdir = 0xc0 | ssd130x->com_invdir << 3; Can 0xc0 and 3 be GENMASK()'ed and defined? ... > + /* Set clock frequency */ > + dclk = ((ssd130x->dclk_div - 1) & 0xf) | (ssd130x->dclk_frq & 0xf) << 4; GENMASK() ? ... > + u32 mode = ((ssd130x->area_color_enable ? 0x30 : 0) | > + (ssd130x->low_power ? 5 : 0)); With if's it will look better. u32 mode = 0; if (ssd130x->area_color_enable) mode |= 0x30; if (ssd130x->low_power) mode |= 5; ... > + /* Turn on the DC-DC Charge Pump */ > + chargepump = BIT(4) | (ssd130x->device_info->need_chargepump ? BIT(2) : 0); Ditto. ... > + for (i = 0; i < ARRAY_SIZE(ssd130x->lookup_table); ++i) { i++ should work as well. > + u8 val = ssd130x->lookup_table[i]; > + > + if (val < 31 || val > 63) > + dev_warn(ssd130x->dev, > + "lookup table index %d value out of range 31 <= %d <= 63\n", > + i, val); > + ret = ssd130x_write_cmd(ssd130x, 1, val); > + if (ret < 0) > + return ret; > + } ... > + u8 *buf = NULL; > + Redundant blank line, not sure if checkpatch catches this. > + struct drm_rect fullscreen = { > + .x1 = 0, > + .x2 = ssd130x->width, > + .y1 = 0, > + .y2 = ssd130x->height, > + }; ... > +power_off: out_power_off: ? ... > + ret = PTR_ERR(ssd130x->vbat_reg); > + if (ret == -ENODEV) > + ssd130x->vbat_reg = NULL; > + else > + return dev_err_probe(dev, ret, "Failed to get VBAT regulator\n"); Can it be ret = PTR_ERR(ssd130x->vbat_reg); if (ret != -ENODEV) return dev_err_probe(dev, ret, "Failed to get VBAT regulator\n"); ssd130x->vbat_reg = NULL; ? ... > + ssd130x = devm_drm_dev_alloc(dev, &ssd130x_drm_driver, > + struct ssd130x_device, drm); > + if (IS_ERR(ssd130x)) { > + dev_err(dev, "Failed to allocate DRM device: %d\n", ret); > + return ssd130x; return dev_err_probe() ? > + } ... > + bl = devm_backlight_device_register(dev, dev_name(dev), dev, ssd130x, > + &ssd130xfb_bl_ops, NULL); > + if (IS_ERR(bl)) { > + ret = PTR_ERR(bl); > + dev_err(dev, "Unable to register backlight device: %d\n", ret); > + return ERR_PTR(ret); Ditto. > + } ... > + ret = drm_dev_register(drm, 0); > + if (ret) { > + dev_err(dev, "DRM device register failed: %d\n", ret); > + return ERR_PTR(ret); Ditto. > + } ... I have feelings that half of my comments were ignored... Maybe I missed the discussion(s). -- With Best Regards, Andy Shevchenko