On 2/11/22 12:33, Andy Shevchenko wrote:
> On Fri, Feb 11, 2022 at 10:19:24AM +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.
>
> ...
>
>> +#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).
>
>> +#include <linux/delay.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/property.h>
>> +#include <linux/pwm.h>
>> +#include <linux/regulator/consumer.h>
>
> ...
>
>> +#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.
> ...
>
>> +/*
>> + * 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.
>> + */
>> +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;
>> +}
>
> ...
>
>> + if (ssd130x->device_info->need_pwm) {
>
> Yeah, unfortunately we still don't have pwm_get_optional()...
>
>> + ret = ssd130x_pwm_enable(ssd130x);
>> + if (ret) {
>> + dev_err(dev, "Failed to enable PWM: %d\n", ret);
>> + regulator_disable(ssd130x->vcc_reg);
>> + return ret;
>> + }
>> + }
>
> ...
>
>> +static void ssd130x_power_off(struct ssd130x_device *ssd130x)
>> +{
>
>> + if (ssd130x->device_info->need_pwm) {
>
> Redundant check. The two below are NULL-aware.
>
Ok, I'll drop it.
>> + pwm_disable(ssd130x->pwm);
>> + pwm_put(ssd130x->pwm);
>> + }
>> +
>> + regulator_disable(ssd130x->vcc_reg);
>> +}
>
> ...
>
>> + ret = ssd130x_write_cmd(ssd130x, 2, SSD130X_SET_COM_PINS_CONFIG, compins);
>> + if (ret < 0)
>> + return ret;
>
>> +
>> +
>
> One blank line is enough.
>
Indeed, that was a left over when changing this to use the macros.
> ...
>
>> + 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]
>> + 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_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
