Re: [PATCH] fbdev: sh_mobile_lcdcfb: Restore the per-overlay sysfs attributes

[Shixiong Ou]

On 2026/9/11 05:15, Helge Deller wrote:

On 9/7/26 04:18, Karl Mehltretter wrote:

The ovl_* files documented in
Documentation/ABI/testing/sysfs-devices-platform-sh_mobile_lcdc_fb no
longer exist.

Commit a979182a2453 ("fbdev: lcdcfb: Register sysfs groups through driver

core") moved the attributes from each overlay's framebuffer device to
the platform driver's dev_groups and renamed them overlay_*. There is
now only one set of attributes for the whole LCDC. The callbacks still
expect dev_get_drvdata() to return a struct fb_info, but the platform
device holds struct sh_mobile_lcdc_priv, so they access the wrong
structure.

Restore the documented names and register the group on each overlay's
framebuffer device with device_add_groups(). Remove it with
device_remove_groups() before unregistering the framebuffer. Skip

creation when info->dev is NULL, as the old device_create_file() calls did.

Drop the CONFIG_FB_DEVICE guard, since the driver already depends on it.

Fixes: a979182a2453 ("fbdev: lcdcfb: Register sysfs groups through driver core")

Cc: sta...@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltret...@gmail.com>
---
Found while reviewing the sysfs ABI documentation.

Compile-tested only (allmodconfig, W=1), I have no SH-Mobile hardware.

This all seems correct, but since it reverts a few of the last patches
I'd prefer that some other person could also review it....

Looks good to me, and I agree .dev_groups is wrong here.

Shixiong.

  drivers/video/fbdev/sh_mobile_lcdcfb.c | 37 +++++++++++++++++---------
  1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/drivers/video/fbdev/sh_mobile_lcdcfb.c b/drivers/video/fbdev/sh_mobile_lcdcfb.c

index e8324b01700f..18fc4e465283 100644
--- a/drivers/video/fbdev/sh_mobile_lcdcfb.c
+++ b/drivers/video/fbdev/sh_mobile_lcdcfb.c

@@ -1337,22 +1337,24 @@ overlay_rop3_store(struct device *dev, struct device_attribute *attr,

      return count;
  }
  -static DEVICE_ATTR_RW(overlay_alpha);
-static DEVICE_ATTR_RW(overlay_mode);
-static DEVICE_ATTR_RW(overlay_position);
-static DEVICE_ATTR_RW(overlay_rop3);
-
-static struct attribute *overlay_sysfs_attrs[] __maybe_unused = {
-    &dev_attr_overlay_alpha.attr,
-    &dev_attr_overlay_mode.attr,
-    &dev_attr_overlay_position.attr,
-    &dev_attr_overlay_rop3.attr,
+static struct device_attribute dev_attr_ovl_alpha =
+    __ATTR(ovl_alpha, 0644, overlay_alpha_show, overlay_alpha_store);
+static struct device_attribute dev_attr_ovl_mode =
+    __ATTR(ovl_mode, 0644, overlay_mode_show, overlay_mode_store);
+static struct device_attribute dev_attr_ovl_position =

+    __ATTR(ovl_position, 0644, overlay_position_show, overlay_position_store);

+static struct device_attribute dev_attr_ovl_rop3 =
+    __ATTR(ovl_rop3, 0644, overlay_rop3_show, overlay_rop3_store);
+
+static struct attribute *overlay_sysfs_attrs[] = {
+    &dev_attr_ovl_alpha.attr,
+    &dev_attr_ovl_mode.attr,
+    &dev_attr_ovl_position.attr,
+    &dev_attr_ovl_rop3.attr,
      NULL,
  };
  -#ifdef CONFIG_FB_DEVICE
  ATTRIBUTE_GROUPS(overlay_sysfs);
-#endif

    static const struct fb_fix_screeninfo sh_mobile_lcdc_overlay_fix  = {

      .id =        "SH Mobile LCDC",

@@ -1513,6 +1515,7 @@ sh_mobile_lcdc_overlay_fb_unregister(struct sh_mobile_lcdc_overlay *ovl)

      if (info == NULL || info->dev == NULL)
          return;
  +    device_remove_groups(info->dev, overlay_sysfs_groups);
      unregister_framebuffer(ovl->info);
  }

  @@ -1530,6 +1533,15 @@ sh_mobile_lcdc_overlay_fb_register(struct sh_mobile_lcdc_overlay *ovl)

      if (ret < 0)
          return ret;
  +    /* The framebuffer device is optional, see fb_device_create(). */
+    if (info->dev) {

I think this needs to be:
    if (dev_of_fbinfo(info)) {
to avoid compile error when CONFIG_FB_DEVICE=n.

+        ret = device_add_groups(info->dev, overlay_sysfs_groups);

same here. dev_of_fbinfo(info).

+        if (ret < 0) {
+            unregister_framebuffer(info);
+            return ret;
+        }
+    }
+
      dev_info(lcdc->dev, "registered %s/overlay %u as %dx%d %dbpp.\n",
           dev_name(lcdc->dev), ovl->index, info->var.xres,
           info->var.yres, info->var.bits_per_pixel);

@@ -2637,7 +2649,6 @@ static int sh_mobile_lcdc_probe(struct platform_device *pdev)

  static struct platform_driver sh_mobile_lcdc_driver = {
      .driver        = {
          .name        = "sh_mobile_lcdc_fb",
-        .dev_groups    = overlay_sysfs_groups,
          .pm        = &sh_mobile_lcdc_dev_pm_ops,
      },
      .probe        = sh_mobile_lcdc_probe,

base-commit: 986c24e0fe44f844b44d365b71ce831947f50298