Re: [PATCH v4 19/19] auxdisplay: ht16k33: Add LED support

Hi Randy,

On Tue, Jul 27, 2021 at 11:05 PM Randy Dunlap [off-list ref] wrote:

On 7/27/21 7:04 AM, Geert Uytterhoeven wrote:

quoted

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@linux-m68k.org>
---
v4:
  - Add missing select LEDS_CLASS,

Since LEDS_CLASS depends on NEW_LEDS, does this also need to
select NEW_LEDS?

Right, I missed that.  It needs to select both NEW_LEDS and LED_CLASS.
Do I need to resend the whole series, or can this be fixed while
applying?

and similar for INPUT_MATRIXKMAP: it depends on INPUT.

HT16K33 already depends on INPUT.

However, selecting (enabling) an entire subsystem is not a
preferable thing to do.

Unfortunately we have no choice, unless we untangle the depends/select
web first:

HT16K33 depends on NEW_LEDS, select LEDS_CLASS:

    drivers/leds/Kconfig:9:error: recursive dependency detected!
    drivers/leds/Kconfig:9:     symbol NEW_LEDS is selected by SENSORS_APPLESMC
    drivers/hwmon/Kconfig:324:  symbol SENSORS_APPLESMC depends on HWMON
    drivers/hwmon/Kconfig:6:    symbol HWMON is selected by EEEPC_LAPTOP
    drivers/platform/x86/Kconfig:305:   symbol EEEPC_LAPTOP depends on
ACPI_VIDEO

HT16K33 depends on LEDS_CLASS:

    drivers/leds/Kconfig:17:error: recursive dependency detected!
    drivers/leds/Kconfig:17:    symbol LEDS_CLASS depends on NEW_LEDS
    drivers/leds/Kconfig:9:     symbol NEW_LEDS is selected by SENSORS_APPLESMC
    drivers/hwmon/Kconfig:324:  symbol SENSORS_APPLESMC depends on HWMON
    drivers/hwmon/Kconfig:6:    symbol HWMON is selected by EEEPC_LAPTOP
    drivers/platform/x86/Kconfig:305:   symbol EEEPC_LAPTOP depends on
ACPI_VIDEO

quoted

--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig

@@ -176,6 +176,7 @@ config HT16K33
      select FB_SYS_IMAGEBLIT
      select INPUT_MATRIXKMAP
      select FB_BACKLIGHT
+     select LEDS_CLASS
      select LINEDISP
      help
        Say yes here to add support for Holtek HT16K33, RAM mapping 16*8

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds