linux-kernel - Re: [PATCH v2 2/4] staging: fbtft: Make FB

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Message-ID: <CAHp75VeroxzYs7GScKMv-gOFqJz_U=561b5FH6ifdo2WQNYNyQ@mail.gmail.com>
Date: Sat, 27 Dec 2025 16:15:22 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Chintan Patel <chintanlike@...il.com>
Cc: linux-fbdev@...r.kernel.org, linux-staging@...ts.linux.dev, 
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, tzimmermann@...e.de, andy@...nel.org, 
	deller@....de, gregkh@...uxfoundation.org
Subject: Re: [PATCH v2 2/4] staging: fbtft: Make FB_DEVICE dependency optional

On Fri, Dec 19, 2025 at 7:43 AM Chintan Patel <chintanlike@...il.com> wrote:
>
> fbtft provides sysfs interfaces for debugging and gamma configuration,
> but these are not required for the core driver.
>
> Drop the hard dependency on CONFIG_FB_DEVICE and make sysfs support
> optional by using dev_of_fbinfo() at runtime. When FB_DEVICE is disabled,
> sysfs operations are skipped while the code remains buildable and
> type-checked.
>
> v2:
> - Replace CONFIG_FB_DEVICE ifdefs with runtime checks
> - Use dev_of_fbinfo() to guard sysfs creation and removal
>
> Suggested-by: Thomas Zimmermann <tzimmermann@...e.de>
> Suggested-by: Helge Deller <deller@....de>
> Signed-off-by: Chintan Patel <chintanlike@...il.com>
> ---
>  drivers/staging/fbtft/Kconfig       |  5 ++++-
>  drivers/staging/fbtft/fbtft-sysfs.c | 18 ++++++++++++++----
>  2 files changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/staging/fbtft/Kconfig b/drivers/staging/fbtft/Kconfig
> index c2655768209a..578412a2f379 100644
> --- a/drivers/staging/fbtft/Kconfig
> +++ b/drivers/staging/fbtft/Kconfig
> @@ -2,11 +2,14 @@
>  menuconfig FB_TFT
>         tristate "Support for small TFT LCD display modules"
>         depends on FB && SPI
> -       depends on FB_DEVICE
>         depends on BACKLIGHT_CLASS_DEVICE
>         depends on GPIOLIB || COMPILE_TEST
>         select FB_BACKLIGHT
>         select FB_SYSMEM_HELPERS_DEFERRED
> +       help
> +         Support for small TFT LCD display modules over SPI bus. FB_DEVICE
> +         is not required, but if enabled, provides sysfs interface for debugging
> +         and gamma curve configuration.
>
>  if FB_TFT
>
> diff --git a/drivers/staging/fbtft/fbtft-sysfs.c b/drivers/staging/fbtft/fbtft-sysfs.c
> index e45c90a03a90..848702fc871a 100644
> --- a/drivers/staging/fbtft/fbtft-sysfs.c
> +++ b/drivers/staging/fbtft/fbtft-sysfs.c
> @@ -203,14 +203,24 @@ static struct device_attribute debug_device_attr =
>
>  void fbtft_sysfs_init(struct fbtft_par *par)
>  {
> -       device_create_file(par->info->dev, &debug_device_attr);
> +       struct device *dev = dev_of_fbinfo(par->info);
> +
> +       if (!dev)
> +               return;
> +
> +       device_create_file(dev, &debug_device_attr);
>         if (par->gamma.curves && par->fbtftops.set_gamma)
> -               device_create_file(par->info->dev, &gamma_device_attrs[0]);
> +               device_create_file(dev, &gamma_device_attrs[0]);
>  }
>
>  void fbtft_sysfs_exit(struct fbtft_par *par)
>  {
> -       device_remove_file(par->info->dev, &debug_device_attr);
> +       struct device *dev = dev_of_fbinfo(par->info);
> +
> +       if (!dev)
> +               return;
> +
> +       device_remove_file(dev, &debug_device_attr);
>         if (par->gamma.curves && par->fbtftops.set_gamma)
> -               device_remove_file(par->info->dev, &gamma_device_attrs[0]);
> +               device_remove_file(dev, &gamma_device_attrs[0]);
>  }
> --
> 2.43.0
>


-- 
With Best Regards,
Andy Shevchenko