On 12/11/24 00:37, Helge Deller wrote:

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On 12/10/24 16:41, Thomas Zimmermann wrote:

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Hi


Am 10.12.24 um 15:34 schrieb Helge Deller:

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On 12/10/24 15:29, Helge Deller wrote:

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On 12/10/24 15:09, Thomas Zimmermann wrote:

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diff --git a/drivers/staging/fbtft/Kconfig b/drivers/staging/fbtft/Kconfig
index 77ab44362f16..577e91ff7bf6 100644
--- a/drivers/staging/fbtft/Kconfig
+++ b/drivers/staging/fbtft/Kconfig

@@ -3,6 +3,7 @@ menuconfig FB_TFT

      tristate "Support for small TFT LCD display modules"
      depends on FB && SPI
      depends on FB_DEVICE
+    depends on BACKLIGHT_DEVICE_CLASS

Typo. Should be BACKLIGHT_CLASS_DEVICE...

Ah, thanks. I'll better check the rest of the series for similar mistakes.

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Beside the typo:
In this case, doesn't it make sense to "select BACKLIGHT_DEVICE_CLASS" instead?

That causes the dependency error mentioned in the commit message. This time it's just for fbtft instead of shmobilefb.

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If people want the fbtft, backlight support should be enabled too.

As a user-visible option, it should not be auto-selected
unnecessarily.

Right, it should not be auto-selected.
Unless if fbtft really needs it enabled to function.
IMHO all fb/drm drivers have higher priority than some low-level
background backlight controller code.

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The DRM panel drivers already depend on the backlight
instead of selecting it. It's the correct approach.

Sounds wrong IMHO.

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As I mentioned
in the cover letter, the few remaining driver that select it should
probably be updated.

That dependency sounds weird, but maybe I simply misunderstand your logic...?

As a Linux end user I usually know which graphic cards are in my machine
and which ones I want to enable.
But as a normal user I think I shouldn't be expected to know
that I first need to enable the "backlight class device"
so that I'm then able to afterwards enable the fbtft (or any other drm/fb driver).

Am I wrong?

Looking closer on this...
You propose:

--- a/drivers/staging/fbtft/Kconfig
+++ b/drivers/staging/fbtft/Kconfig

@@ -3,6 +3,7 @@ menuconfig FB_TFT
      tristate "Support for small TFT LCD display modules"
      depends on FB && SPI
      depends on FB_DEVICE
+    depends on BACKLIGHT_DEVICE_CLASS
      depends on GPIOLIB || COMPILE_TEST
      select FB_BACKLIGHT

So, it will depend on BACKLIGHT_DEVICE_CLASS.
But there is "select FB_BACKLIGHT" as well, which is:
config FB_BACKLIGHT
         tristate
         depends on FB
         select BACKLIGHT_CLASS_DEVICE

So, you end up with selecting and depending on BACKLIGHT_CLASS_DEVICE ?