On Fri, Feb 04, 2022 at 02:43:45PM +0100, Javier Martinez Canillas wrote:
Add a DRM driver for SSD1305, SSD1306, SSD1307 and SSD1309 Solomon OLED controllers that can be programmed via an I2C interface. This is a port of the ssd1307fb driver that already supports these devices.
A Device Tree binding is not added because the DRM driver is compatible with the existing binding for the ssd1307fb driver.
...
+/*
- DRM driver for Solomon SSD130X OLED displays
- Copyright 2022 Red Hat Inc.
- Based on drivers/video/fbdev/ssd1307fb.c
- Copyright 2012 Free Electrons
No need for this blank line.
- */
...
+struct ssd130x_device {
- struct drm_device drm;
- struct drm_simple_display_pipe pipe;
- struct drm_display_mode mode;
- struct drm_connector connector;
- struct i2c_client *client;
Can we logically separate hw protocol vs hw interface from day 1, please? This will allow to add SPI support for this panel much easier.
Technically I would like to see here
struct device *dev;
and probably (I haven't looked into design)
struct ssd130x_ops *ops;
or something alike.
- const struct ssd130x_deviceinfo *device_info;
- unsigned area_color_enable : 1;
- unsigned com_invdir : 1;
- unsigned com_lrremap : 1;
- unsigned com_seq : 1;
- unsigned lookup_table_set : 1;
- unsigned low_power : 1;
- unsigned seg_remap : 1;
- u32 com_offset;
- u32 contrast;
- u32 dclk_div;
- u32 dclk_frq;
- u32 height;
- u8 lookup_table[4];
- u32 page_offset;
- u32 col_offset;
- u32 prechargep1;
- u32 prechargep2;
- struct backlight_device *bl_dev;
- struct pwm_device *pwm;
- struct gpio_desc *reset;
- struct regulator *vbat_reg;
- u32 vcomh;
- u32 width;
- /* Cached address ranges */
- u8 col_start;
- u8 col_end;
- u8 page_start;
- u8 page_end;
+};
...
+static inline int ssd130x_write_value(struct i2c_client *client, u8 value)
Not sure inline does anything useful here. Ditto for the rest similar cases.
...
+static inline int ssd130x_write_cmd(struct i2c_client *client, int count,
/* u8 cmd, u8 value, ... */...)+{
- va_list ap;
- u8 value;
- int ret;
- va_start(ap, count);
- while (count--) {
value = va_arg(ap, int);ret = ssd130x_write_value(client, (u8)value);if (ret)goto out_end;- }
I'm wondering if this can be written in a form
do { ... } while (--count);
In this case it will give a hint that count can't be 0.
+out_end:
- va_end(ap);
- return ret;
+}
...
- ssd130x->pwm = pwm_get(dev, NULL);
- if (IS_ERR(ssd130x->pwm)) {
dev_err(dev, "Could not get PWM from device tree!\n");
"device tree" is a bit confusing here if I run this on ACPI. Maybe something like "firmware description"?
return PTR_ERR(ssd130x->pwm);- }
...
- /* Set initial contrast */
- ret = ssd130x_write_cmd(ssd130x->client, 2, SSD130X_CONTRAST, ssd130x->contrast);
Creating a local variable for client allows to: - make lines shorter and might even be less LOCs - allow to convert struct device to client in one place (as per my above comment)
Ditto for other similar cases.
- if (ret < 0)
return ret;
...
for (i = 0; i < ARRAY_SIZE(ssd130x->lookup_table); ++i) {
i++ should work same way.
}
...
- /* Switch to horizontal addressing mode */
- ret = ssd130x_write_cmd(ssd130x->client, 2, SSD130X_SET_ADDRESS_MODE,
SSD130X_SET_ADDRESS_MODE_HORIZONTAL);- if (ret < 0)
return ret;- return 0;
Can it be
return ssd130x_write_cmd(...);
?
...
- unsigned int line_length = DIV_ROUND_UP(width, 8);
- unsigned int pages = DIV_ROUND_UP(height, 8);
For power of two there are more efficient roundup()/rounddown() (or with _ in the names, I don't remember by heart).
...
for (k = 0; k < m; k++) {
u8 byte = buf[(8 * i + k) * line_length +j / 8];
One line?
u8 bit = (byte >> (j % 8)) & 1;data |= bit << k;}
...
+static int ssd130x_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
const struct drm_display_mode *mode)+{
- struct ssd130x_device *ssd130x = drm_to_ssd130x(pipe->crtc.dev);
- if (mode->hdisplay != ssd130x->mode.hdisplay &&
mode->vdisplay != ssd130x->mode.vdisplay)return MODE_ONE_SIZE;
- else if (mode->hdisplay != ssd130x->mode.hdisplay)
return MODE_ONE_WIDTH;- else if (mode->vdisplay != ssd130x->mode.vdisplay)
return MODE_ONE_HEIGHT;
'else' in both cases is redundant.
- return MODE_OK;
+}
...
+poweroff:
out_power_off: ?
...
- if (!fb)
return;
Can it happen?
...
- drm_mode_probed_add(connector, mode);
- drm_set_preferred_mode(connector, mode->hdisplay, mode->vdisplay);
- return 1;
Positive code, what is the meaning of it?
...
- if (device_property_read_u32(dev, "solomon,prechargep2", &ssd130x->prechargep2))
ssd130x->prechargep2 = 2;
You can drop conditionals for the optional properties
ssd130x->prechargep2 = 2; device_property_read_u32(dev, "solomon,prechargep2", &ssd130x->prechargep2);
and so on for the similar.
...
- ssd130x->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
- if (IS_ERR(ssd130x->reset)) {
ret = PTR_ERR(ssd130x->reset);dev_err(dev, "Failed to get reset gpio: %d\n", ret);return ret;
Why not
return dev_err_probe()?
Each time you call it for deferred probe, it will spam logs.
- }
- ssd130x->vbat_reg = devm_regulator_get_optional(dev, "vbat");
- if (IS_ERR(ssd130x->vbat_reg)) {
ret = PTR_ERR(ssd130x->vbat_reg);if (ret == -ENODEV) {ssd130x->vbat_reg = NULL;
} else {dev_err(dev, "Failed to get VBAT regulator: %d\n", ret);return ret;}
Ditto ?
- }
...
- if (IS_ERR(ssd130x)) {
ret = PTR_ERR(ssd130x);dev_err(dev, "Failed to allocate DRM device: %d\n", ret);return ret;- }
Ditto.
...
- i2c_set_clientdata(client, ssd130x);
Wondering if you can split i2c part from the core part and perhaps use regmap to access the device.
...
- if (IS_ERR(bl)) {
ret = PTR_ERR(bl);dev_err(dev, "Unable to register backlight device: %d\n", ret);return ret;
return dev_err_probe();
- }
...
- ret = drm_dev_register(drm, 0);
- if (ret) {
dev_err(dev, "DRM device register failed: %d\n", ret);return ret;- }
Ditto.
...
- {},
Comma is not needed in terminator entry.
...
+static struct i2c_driver ssd130x_i2c_driver = {
- .driver = {
.name = DRIVER_NAME,.of_match_table = ssd130x_of_match,- },
- .probe_new = ssd130x_probe,
- .remove = ssd130x_remove,
- .shutdown = ssd130x_shutdown,
+};
Redundant blank line.
+module_i2c_driver(ssd130x_i2c_driver);