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Date: Thu, 30 Sep 2021 12:57:09 +0200
From: Robin van der Gracht <robin@...tonic.nl>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Miguel Ojeda <ojeda@...nel.org>, Rob Herring <robh+dt@...nel.org>,
Paul Burton <paulburton@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Pavel Machek <pavel@....cz>, Marek Behun <marek.behun@....cz>,
devicetree@...r.kernel.org, linux-leds@...r.kernel.org,
linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
Marek Behún <kabel@...nel.org>
Subject: Re: [PATCH v6 19/19] auxdisplay: ht16k33: Add LED support
Hi Geert,
On 2021-09-14 16:38, Geert Uytterhoeven wrote:
> Instantiate a single LED based on the "led" subnode in DT.
> This allows the user to control display brightness and blinking (backed
> by hardware support) through the LED class API and triggers, and exposes
> the display color. The LED will be named
> "auxdisplay:<color>:<function>".
>
> When running in dot-matrix mode and if no "led" subnode is found, the
> driver falls back to the traditional backlight mode, to preserve
> backwards compatibility.
>
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Reviewed-by: Marek Behún <kabel@...nel.org>
> ---
> v6:
> - Add Reviewed-by,
> - Reorder operations in ht16k33_led_probe() to ease future conversion
> to device properties,
>
> v5:
> - Add missing select NEW_LEDS,
>
> v4:
> - Add missing select LEDS_CLASS,
>
> v3:
> - Remove unneeded C++ comment,
> - Use "err" instead of "error" to be consistent with existing driver
> naming style,
> - Make the creation of the LED device dependent on the presence of the
> "led" subnode in DT, so it can be used in dot-matrix mode too.
> - Use led_init_data() and devm_led_classdev_register_ext() to retrieve
> all LED properties from DT, instead of manual LED name construction
> based on just the "color" property,
>
> v2:
> - Use "auxdisplay" instead of DRIVER_NAME in LED name.
> ---
> drivers/auxdisplay/Kconfig | 2 +
> drivers/auxdisplay/ht16k33.c | 124 ++++++++++++++++++++++++++++++-----
> 2 files changed, 109 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
> index 42fc7b155de09dbc..e32ef7f9945d49b2 100644
> --- a/drivers/auxdisplay/Kconfig
> +++ b/drivers/auxdisplay/Kconfig
> @@ -176,6 +176,8 @@ config HT16K33
> select FB_SYS_IMAGEBLIT
> select INPUT_MATRIXKMAP
> select FB_BACKLIGHT
> + select NEW_LEDS
> + select LEDS_CLASS
> select LINEDISP
> help
> Say yes here to add support for Holtek HT16K33, RAM mapping 16*8
> diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
> index 3b555e119e326cec..89ee5b4b3dfccb68 100644
> --- a/drivers/auxdisplay/ht16k33.c
> +++ b/drivers/auxdisplay/ht16k33.c
> @@ -18,6 +18,7 @@
> #include <linux/backlight.h>
> #include <linux/input.h>
> #include <linux/input/matrix_keypad.h>
> +#include <linux/leds.h>
> #include <linux/workqueue.h>
> #include <linux/mm.h>
>
> @@ -34,6 +35,10 @@
>
> #define REG_DISPLAY_SETUP 0x80
> #define REG_DISPLAY_SETUP_ON BIT(0)
> +#define REG_DISPLAY_SETUP_BLINK_OFF (0 << 1)
> +#define REG_DISPLAY_SETUP_BLINK_2HZ (1 << 1)
> +#define REG_DISPLAY_SETUP_BLINK_1HZ (2 << 1)
> +#define REG_DISPLAY_SETUP_BLINK_0HZ5 (3 << 1)
>
> #define REG_ROWINT_SET 0xA0
> #define REG_ROWINT_SET_INT_EN BIT(0)
> @@ -94,12 +99,14 @@ struct ht16k33_seg {
> struct ht16k33_priv {
> struct i2c_client *client;
> struct delayed_work work;
> + struct led_classdev led;
> struct ht16k33_keypad keypad;
> union {
> struct ht16k33_fbdev fbdev;
> struct ht16k33_seg seg;
> };
> enum display_type type;
> + uint8_t blink;
> };
>
> static const struct fb_fix_screeninfo ht16k33_fb_fix = {
> @@ -158,7 +165,7 @@ static DEVICE_ATTR(map_seg14, 0644, map_seg_show,
> map_seg_store);
>
> static int ht16k33_display_on(struct ht16k33_priv *priv)
> {
> - uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON;
> + uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON | priv->blink;
>
> return i2c_smbus_write_byte(priv->client, data);
> }
> @@ -173,8 +180,10 @@ static int ht16k33_brightness_set(struct ht16k33_priv
> *priv,
> {
> int err;
>
> - if (brightness == 0)
> + if (brightness == 0) {
> + priv->blink = REG_DISPLAY_SETUP_BLINK_OFF;
> return ht16k33_display_off(priv);
> + }
>
> err = ht16k33_display_on(priv);
> if (err)
> @@ -184,6 +193,49 @@ static int ht16k33_brightness_set(struct ht16k33_priv
> *priv,
> REG_BRIGHTNESS | (brightness - 1));
> }
>
> +static int ht16k33_brightness_set_blocking(struct led_classdev *led_cdev,
> + enum led_brightness brightness)
> +{
> + struct ht16k33_priv *priv = container_of(led_cdev, struct ht16k33_priv,
> + led);
> +
> + return ht16k33_brightness_set(priv, brightness);
> +}
> +
> +static int ht16k33_blink_set(struct led_classdev *led_cdev,
> + unsigned long *delay_on, unsigned long *delay_off)
> +{
> + struct ht16k33_priv *priv = container_of(led_cdev, struct ht16k33_priv,
> + led);
> + unsigned int delay;
> + uint8_t blink;
> + int err;
> +
> + if (!*delay_on && !*delay_off) {
> + blink = REG_DISPLAY_SETUP_BLINK_1HZ;
> + delay = 1000;
> + } else if (*delay_on <= 750) {
> + blink = REG_DISPLAY_SETUP_BLINK_2HZ;
> + delay = 500;
> + } else if (*delay_on <= 1500) {
> + blink = REG_DISPLAY_SETUP_BLINK_1HZ;
> + delay = 1000;
> + } else {
> + blink = REG_DISPLAY_SETUP_BLINK_0HZ5;
> + delay = 2000;
> + }
> +
> + err = i2c_smbus_write_byte(priv->client,
> + REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON |
> + blink);
> + if (err)
> + return err;
> +
> + priv->blink = blink;
> + *delay_on = *delay_off = delay;
> + return 0;
> +}
> +
> static void ht16k33_fb_queue(struct ht16k33_priv *priv)
> {
> struct ht16k33_fbdev *fbdev = &priv->fbdev;
> @@ -425,6 +477,35 @@ static void ht16k33_seg14_update(struct work_struct
> *work)
> i2c_smbus_write_i2c_block_data(priv->client, 0, ARRAY_SIZE(buf), buf);
> }
>
> +static int ht16k33_led_probe(struct device *dev, struct led_classdev *led,
> + unsigned int brightness)
> +{
> + struct led_init_data init_data = {};
> + struct device_node *node;
> + int err;
> +
> + /* The LED is optional */
> + node = of_get_child_by_name(dev->of_node, "led");
> + if (!node)
> + return 0;
> +
> + init_data.fwnode = of_fwnode_handle(node);
> + init_data.devicename = "auxdisplay";
> + init_data.devname_mandatory = true;
> +
> + led->brightness_set_blocking = ht16k33_brightness_set_blocking;
> + led->blink_set = ht16k33_blink_set;
> + led->flags = LED_CORE_SUSPENDRESUME;
> + led->brightness = brightness;
> + led->max_brightness = MAX_BRIGHTNESS;
What do you think about adding a default trigger and making it 'backlight'?
led->default_trigger = "blacklight";
Or as an alternative, suggesting linux,default-trigger = "backlight" in the
docs? Since the led class won't respond to blank events by just making it's
function LED_FUNCTION_BACKLIGHT.
led {
function = LED_FUNCTION_BACKLIGHT;
color = <LED_COLOR_ID_GREEN>;
linux,default-trigger = "backlight";
};
I noticed blanking is broken. The backlight device (or LED device with
backlight trigger) doens't get notified when the framebuffer is blanked since
the driver doesn't implement fb_blank.
Right now:
echo 1 > /sys/class/graphics/fb0/blank
|
sh: write error: Invalid argument
Due to:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/video/fbdev/core/fbmem.c?h=v5.15-rc3#n1078
Something like this fixes it.
diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 89ee5b4b3dfc..0883d5252c81 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -346,6 +346,15 @@ static int ht16k33_mmap(struct fb_info *info, struct
vm_area_struct *vma)
return vm_map_pages_zero(vma, &pages, 1);
}
+/*
+ * Blank events will be passed to the backlight device (or the LED device if
+ * it's trigger is 'backlight') when we return 0 here.
+ */
+static int ht16k33_blank(int blank, struct fb_info *info)
+{
+ return 0;
+}
+
static const struct fb_ops ht16k33_fb_ops = {
.owner = THIS_MODULE,
.fb_read = fb_sys_read,
@@ -354,6 +363,7 @@ static const struct fb_ops ht16k33_fb_ops = {
.fb_copyarea = sys_copyarea,
.fb_imageblit = sys_imageblit,
.fb_mmap = ht16k33_mmap,
+ .fb_blank = ht16k33_blank,
};
/*
Feel free to include (something like) this in the patch stack.
> +
> + err = devm_led_classdev_register_ext(dev, led, &init_data);
> + if (err)
> + dev_err(dev, "Failed to register LED\n");
You might want to call ht16k33_brightness_set(priv, brightness) here to get a
know value into the display setup register (0x80).
Right now if I enable hardware blinking and (soft)reboot my board it keeps on
blinking even after a re-probe.
> +
> + return err;
> +}
> +
> static int ht16k33_keypad_probe(struct i2c_client *client,
> struct ht16k33_keypad *keypad)
> {
> @@ -498,24 +579,28 @@ static int ht16k33_fbdev_probe(struct device *dev,
> struct ht16k33_priv *priv,
> uint32_t brightness)
> {
> struct ht16k33_fbdev *fbdev = &priv->fbdev;
> - struct backlight_properties bl_props;
> - struct backlight_device *bl;
> + struct backlight_device *bl = NULL;
> int err;
>
> - /* Backlight */
> - memset(&bl_props, 0, sizeof(struct backlight_properties));
> - bl_props.type = BACKLIGHT_RAW;
> - bl_props.max_brightness = MAX_BRIGHTNESS;
> + if (!priv->led.dev) {
> + /* backwards compatibility with DT lacking an led subnode */
> + struct backlight_properties bl_props;
>
> - bl = devm_backlight_device_register(dev, DRIVER_NAME"-bl", dev, priv,
> - &ht16k33_bl_ops, &bl_props);
> - if (IS_ERR(bl)) {
> - dev_err(dev, "failed to register backlight\n");
> - return PTR_ERR(bl);
> - }
> + memset(&bl_props, 0, sizeof(struct backlight_properties));
> + bl_props.type = BACKLIGHT_RAW;
> + bl_props.max_brightness = MAX_BRIGHTNESS;
> +
> + bl = devm_backlight_device_register(dev, DRIVER_NAME"-bl", dev,
> + priv, &ht16k33_bl_ops,
> + &bl_props);
> + if (IS_ERR(bl)) {
> + dev_err(dev, "failed to register backlight\n");
> + return PTR_ERR(bl);
> + }
>
> - bl->props.brightness = brightness;
> - ht16k33_bl_update_status(bl);
> + bl->props.brightness = brightness;
> + ht16k33_bl_update_status(bl);
> + }
>
> /* Framebuffer (2 bytes per column) */
> BUILD_BUG_ON(PAGE_SIZE < HT16K33_FB_SIZE);
> @@ -575,7 +660,7 @@ static int ht16k33_seg_probe(struct device *dev, struct
> ht16k33_priv *priv,
> struct ht16k33_seg *seg = &priv->seg;
> int err;
>
> - err = ht16k33_brightness_set(priv, MAX_BRIGHTNESS);
> + err = ht16k33_brightness_set(priv, brightness);
This looks like a bugfix for patch 17, maybe move this change there?
> if (err)
> return err;
>
> @@ -653,6 +738,11 @@ static int ht16k33_probe(struct i2c_client *client)
> dft_brightness = MAX_BRIGHTNESS;
> }
>
> + /* LED */
> + err = ht16k33_led_probe(dev, &priv->led, dft_brightness);
> + if (err)
> + return err;
> +
> /* Keypad */
> if (client->irq > 0) {
> err = ht16k33_keypad_probe(client, &priv->keypad);
Gr{oetje,eeting}s,
Robin
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