On Mon, Jan 15, 2018 at 10:58 AM, Sean Young <sean@xxxxxxxx> wrote:
> The NEC µPD16314 can alter the the brightness of the LCD. Make it possible
> to set this via escape sequence Y0 - Y3. B and R were already taken, so
> I picked Y for luminance.
>
> Signed-off-by: Sean Young <sean@xxxxxxxx>
CC'ing Willy and Geert.
> ---
> drivers/auxdisplay/charlcd.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
> index a16c72779722..7a671ad959d1 100644
> --- a/drivers/auxdisplay/charlcd.c
> +++ b/drivers/auxdisplay/charlcd.c
> @@ -39,6 +39,8 @@
> #define LCD_FLAG_F 0x0020 /* Large font mode */
> #define LCD_FLAG_N 0x0040 /* 2-rows mode */
> #define LCD_FLAG_L 0x0080 /* Backlight enabled */
> +#define LCD_BRIGHTNESS_MASK 0x0300 /* Brightness */
> +#define LCD_BRIGHTNESS_SHIFT 8
Not sure about the name (since the brightness is also used in
priv->flags). By the way, should we start using the bitops.h stuff
(e.g. BIT(9) | BIT(8), GENMASK(9, 8)...) in new code? Not sure how
widespread they are.
>
> /* LCD commands */
> #define LCD_CMD_DISPLAY_CLEAR 0x01 /* Clear entire display */
> @@ -490,6 +492,17 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
> charlcd_gotoxy(lcd);
> processed = 1;
> break;
> + case 'Y': /* brightness (luma) */
> + switch (esc[1]) {
> + case '0': /* 25% */
> + case '1': /* 50% */
> + case '2': /* 75% */
> + case '3': /* 100% */
> + priv->flags = (priv->flags & ~(LCD_BRIGHTNESS_MASK)) |
> + (('3' - esc[1]) << LCD_BRIGHTNESS_SHIFT);
> + processed = 1;
> + break;
> + }
> }
>
> /* TODO: This indent party here got ugly, clean it! */
> @@ -507,12 +520,15 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
> ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
> ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
> /* check whether one of F,N flags was changed */
Should we add "or brightness" to the comment?
> - else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N))
> + else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N |
> + LCD_BRIGHTNESS_MASK))
> lcd->ops->write_cmd(lcd,
> LCD_CMD_FUNCTION_SET |
> ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
> ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
> - ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
> + ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0) |
> + ((priv->flags & LCD_BRIGHTNESS_MASK) >>
> + LCD_BRIGHTNESS_SHIFT));
> /* check whether L flag was changed */
> else if ((oldflags ^ priv->flags) & LCD_FLAG_L)
> charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L));
> --
> 2.14.3
>
