linux-kernel - Re: [PATCH 02/13] drm: remove drm_fb_helper

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Date:   Wed, 3 Feb 2021 11:34:50 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Christoph Hellwig <hch@....de>
Cc:     Frederic Barrat <fbarrat@...ux.ibm.com>,
        Andrew Donnellan <ajd@...ux.ibm.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Jessica Yu <jeyu@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        dri-devel@...ts.freedesktop.org, live-patching@...r.kernel.org,
        linux-kbuild@...r.kernel.org
Subject: Re: [PATCH 02/13] drm: remove drm_fb_helper_modinit

On Thu, Jan 28, 2021 at 07:14:10PM +0100, Christoph Hellwig wrote:
> drm_fb_helper_modinit has a lot of boilerplate for what is not very
> simple functionality.  Just open code it in the only caller using
> IS_ENABLED and IS_MODULE, and skip the find_module check as a
> request_module is harmless if the module is already loaded (and not
> other caller has this find_module check either).
> 
> Signed-off-by: Christoph Hellwig <hch@....de>

Hm I thought I've acked this one already somewhere for merging through
your tree.

Acked-by: Daniel Vetter <daniel.vetter@...ll.ch>

> ---
>  drivers/gpu/drm/drm_crtc_helper_internal.h | 10 ---------
>  drivers/gpu/drm/drm_fb_helper.c            | 21 ------------------
>  drivers/gpu/drm/drm_kms_helper_common.c    | 25 +++++++++++-----------
>  3 files changed, 12 insertions(+), 44 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc_helper_internal.h b/drivers/gpu/drm/drm_crtc_helper_internal.h
> index 25ce42e799952c..61e09f8a8d0ff0 100644
> --- a/drivers/gpu/drm/drm_crtc_helper_internal.h
> +++ b/drivers/gpu/drm/drm_crtc_helper_internal.h
> @@ -32,16 +32,6 @@
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_modes.h>
>  
> -/* drm_fb_helper.c */
> -#ifdef CONFIG_DRM_FBDEV_EMULATION
> -int drm_fb_helper_modinit(void);
> -#else
> -static inline int drm_fb_helper_modinit(void)
> -{
> -	return 0;
> -}
> -#endif
> -
>  /* drm_dp_aux_dev.c */
>  #ifdef CONFIG_DRM_DP_AUX_CHARDEV
>  int drm_dp_aux_dev_init(void);
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 4b81195106875d..0b9f1ae1b7864c 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -2499,24 +2499,3 @@ void drm_fbdev_generic_setup(struct drm_device *dev,
>  	drm_client_register(&fb_helper->client);
>  }
>  EXPORT_SYMBOL(drm_fbdev_generic_setup);
> -
> -/* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
> - * but the module doesn't depend on any fb console symbols.  At least
> - * attempt to load fbcon to avoid leaving the system without a usable console.
> - */
> -int __init drm_fb_helper_modinit(void)
> -{
> -#if defined(CONFIG_FRAMEBUFFER_CONSOLE_MODULE) && !defined(CONFIG_EXPERT)
> -	const char name[] = "fbcon";
> -	struct module *fbcon;
> -
> -	mutex_lock(&module_mutex);
> -	fbcon = find_module(name);
> -	mutex_unlock(&module_mutex);
> -
> -	if (!fbcon)
> -		request_module_nowait(name);
> -#endif
> -	return 0;
> -}
> -EXPORT_SYMBOL(drm_fb_helper_modinit);
> diff --git a/drivers/gpu/drm/drm_kms_helper_common.c b/drivers/gpu/drm/drm_kms_helper_common.c
> index 221a8528c9937a..f933da1656eb52 100644
> --- a/drivers/gpu/drm/drm_kms_helper_common.c
> +++ b/drivers/gpu/drm/drm_kms_helper_common.c
> @@ -64,19 +64,18 @@ MODULE_PARM_DESC(edid_firmware,
>  
>  static int __init drm_kms_helper_init(void)
>  {
> -	int ret;
> -
> -	/* Call init functions from specific kms helpers here */
> -	ret = drm_fb_helper_modinit();
> -	if (ret < 0)
> -		goto out;
> -
> -	ret = drm_dp_aux_dev_init();
> -	if (ret < 0)
> -		goto out;
> -
> -out:
> -	return ret;
> +	/*
> +	 * The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
> +	 * but the module doesn't depend on any fb console symbols.  At least
> +	 * attempt to load fbcon to avoid leaving the system without a usable
> +	 * console.
> +	 */
> +	if (IS_ENABLED(CONFIG_DRM_FBDEV_EMULATION) &&
> +	    IS_MODULE(CONFIG_FRAMEBUFFER_CONSOLE) &&
> +	    !IS_ENABLED(CONFIG_EXPERT))
> +		request_module_nowait("fbcon");
> +
> +	return drm_dp_aux_dev_init();
>  }
>  
>  static void __exit drm_kms_helper_exit(void)
> -- 
> 2.29.2
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch