linux-kernel - Re: [PATCH 24/33] Revert "backlight/fbcon: Add FB_EVENT

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Date:   Fri, 24 May 2019 14:14:53 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Daniel Vetter <daniel.vetter@...ll.ch>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Richard Purdie <rpurdie@...ys.net>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Lee Jones <lee.jones@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Yisheng Xie <ysxie@...mail.com>, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH 24/33] Revert "backlight/fbcon: Add FB_EVENT_CONBLANK"

On Fri, May 24, 2019 at 10:53:45AM +0200, Daniel Vetter wrote:
> This reverts commit 994efacdf9a087b52f71e620b58dfa526b0cf928.
> 
> The justification is that if hw blanking fails (i.e. fbops->fb_blank)
> fails, then we still want to shut down the backlight. Which is exactly
> _not_ what fb_blank() does and so rather inconsistent if we end up
> with different behaviour between fbcon and direct fbdev usage. Given
> that the entire notifier maze is getting in the way anyway I figured
> it's simplest to revert this not well justified commit.
> 
> v2: Add static inline to the dummy version.
> 
> Cc: Richard Purdie <rpurdie@...ys.net>
> Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Lee Jones <lee.jones@...aro.org>
> Cc: Daniel Thompson <daniel.thompson@...aro.org>
> Cc: Jingoo Han <jingoohan1@...il.com>
> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: Yisheng Xie <ysxie@...mail.com>
> Cc: linux-fbdev@...r.kernel.org

Hi Daniel

When this goes round again could you add me to the covering letter?

I looked at all three of the patches and no objections on my side but
I'm reluctant to send out acks because I'm not sure I understood the
wider picture well enough.


Daniel.


> ---
>  drivers/video/backlight/backlight.c |  2 +-
>  drivers/video/fbdev/core/fbcon.c    | 14 +-------------
>  drivers/video/fbdev/core/fbmem.c    |  1 +
>  include/linux/fb.h                  |  4 +---
>  include/linux/fbcon.h               |  2 ++
>  5 files changed, 6 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index deb824bef6e2..c55590ec0057 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -46,7 +46,7 @@ static int fb_notifier_callback(struct notifier_block *self,
>  	int fb_blank = 0;
>  
>  	/* If we aren't interested in this event, skip it immediately ... */
> -	if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
> +	if (event != FB_EVENT_BLANK)
>  		return 0;
>  
>  	bd = container_of(self, struct backlight_device, fb_notif);
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 259cdd118475..d9f545f1a81b 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -2350,8 +2350,6 @@ static int fbcon_switch(struct vc_data *vc)
>  static void fbcon_generic_blank(struct vc_data *vc, struct fb_info *info,
>  				int blank)
>  {
> -	struct fb_event event;
> -
>  	if (blank) {
>  		unsigned short charmask = vc->vc_hi_font_mask ?
>  			0x1ff : 0xff;
> @@ -2362,13 +2360,6 @@ static void fbcon_generic_blank(struct vc_data *vc, struct fb_info *info,
>  		fbcon_clear(vc, 0, 0, vc->vc_rows, vc->vc_cols);
>  		vc->vc_video_erase_char = oldc;
>  	}
> -
> -
> -	lock_fb_info(info);
> -	event.info = info;
> -	event.data = &blank;
> -	fb_notifier_call_chain(FB_EVENT_CONBLANK, &event);
> -	unlock_fb_info(info);
>  }
>  
>  static int fbcon_blank(struct vc_data *vc, int blank, int mode_switch)
> @@ -3240,7 +3231,7 @@ int fbcon_fb_registered(struct fb_info *info)
>  	return ret;
>  }
>  
> -static void fbcon_fb_blanked(struct fb_info *info, int blank)
> +void fbcon_fb_blanked(struct fb_info *info, int blank)
>  {
>  	struct fbcon_ops *ops = info->fbcon_par;
>  	struct vc_data *vc;
> @@ -3344,9 +3335,6 @@ static int fbcon_event_notify(struct notifier_block *self,
>  		con2fb = event->data;
>  		con2fb->framebuffer = con2fb_map[con2fb->console - 1];
>  		break;
> -	case FB_EVENT_BLANK:
> -		fbcon_fb_blanked(info, *(int *)event->data);
> -		break;
>  	case FB_EVENT_REMAP_ALL_CONSOLE:
>  		idx = info->node;
>  		fbcon_remap_all(idx);
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index ddc0c16b8bbf..9366fbe99a58 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1068,6 +1068,7 @@ fb_blank(struct fb_info *info, int blank)
>  	event.data = &blank;
>  
>  	early_ret = fb_notifier_call_chain(FB_EARLY_EVENT_BLANK, &event);
> +	fbcon_fb_blanked(info, blank);
>  
>  	if (info->fbops->fb_blank)
>   		ret = info->fbops->fb_blank(blank, info);
> diff --git a/include/linux/fb.h b/include/linux/fb.h
> index 0d86aa31bf8d..1e66fac3124f 100644
> --- a/include/linux/fb.h
> +++ b/include/linux/fb.h
> @@ -137,12 +137,10 @@ struct fb_cursor_user {
>  #define FB_EVENT_GET_CONSOLE_MAP        0x07
>  /*      CONSOLE-SPECIFIC: set console to framebuffer mapping */
>  #define FB_EVENT_SET_CONSOLE_MAP        0x08
> -/*      A hardware display blank change occurred */
> +/*      A display blank is requested       */
>  #define FB_EVENT_BLANK                  0x09
>  /*      Private modelist is to be replaced */
>  #define FB_EVENT_MODE_CHANGE_ALL	0x0B
> -/*	A software display blank change occurred */
> -#define FB_EVENT_CONBLANK               0x0C
>  /*      CONSOLE-SPECIFIC: remap all consoles to new fb - for vga_switcheroo */
>  #define FB_EVENT_REMAP_ALL_CONSOLE      0x0F
>  /*      A hardware display blank early change occurred */
> diff --git a/include/linux/fbcon.h b/include/linux/fbcon.h
> index 305e4f2eddac..d67d7ec51ef9 100644
> --- a/include/linux/fbcon.h
> +++ b/include/linux/fbcon.h
> @@ -14,6 +14,7 @@ int fbcon_mode_deleted(struct fb_info *info,
>  void fbcon_new_modelist(struct fb_info *info);
>  void fbcon_get_requirement(struct fb_info *info,
>  			   struct fb_blit_caps *caps);
> +void fbcon_fb_blanked(struct fb_info *info, int blank);
>  #else
>  static inline void fb_console_init(void) {}
>  static inline void fb_console_exit(void) {}
> @@ -27,6 +28,7 @@ static inline int fbcon_mode_deleted(struct fb_info *info,
>  static inline void fbcon_new_modelist(struct fb_info *info) {}
>  static inline void fbcon_get_requirement(struct fb_info *info,
>  					 struct fb_blit_caps *caps) {}
> +static inline void fbcon_fb_blanked(struct fb_info *info, int blank) {}
>  #endif
>  
>  #endif /* _LINUX_FBCON_H */
> -- 
> 2.20.1
>