Message-id: <1500556.Az9hZml9Y8@amdc3058>
Date:   Tue, 10 Jan 2017 17:09:43 +0100
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Tomi Valkeinen <tomi.valkeinen@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.cz>, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] fbcon: Fix vc attr at deinit


Hi,

On Tuesday, January 10, 2017 04:47:30 PM Takashi Iwai wrote:
> On Thu, 05 Jan 2017 13:26:07 +0100,
> Tomi Valkeinen wrote:
> > 
> > On 04/01/17 15:50, Takashi Iwai wrote:
> > > On Tue, 03 Jan 2017 16:03:22 +0100,
> > > Takashi Iwai wrote:
> > >>
> > >> fbcon can deal with vc_hi_font_mask (the upper 256 chars) and adjust
> > >> the vc attrs dynamically when vc_hi_font_mask is changed at
> > >> fbcon_init().  When the vc_hi_font_mask is set, it remaps the attrs in
> > >> the existing console buffer with one bit shift up (for 9 bits), while
> > >> it remaps with one bit shift down (for 8 bits) when the value is
> > >> cleared.  It works fine as long as the font gets updated after fbcon
> > >> was initialized.
> > >>
> > >> However, we hit a bizarre problem when the console is switched to
> > >> another fb driver (typically from vesafb or efifb to drmfb).  At
> > >> switching to the new fb driver, we temporarily rebind the console to
> > >> the dummy console, then rebind to the new driver.  During the
> > >> switching, we leave the modified attrs as is.  Thus, the new fbcon
> > >> takes over the old buffer as if it were to contain 8 bits chars
> > >> (although the attrs are still shifted for 9 bits), and effectively
> > >> this results in the yellow color texts instead of the original white
> > >> color, as found in the bugzilla entry below.
> > >>
> > >> An easy fix for this is to re-adjust the attrs before leaving the
> > >> fbcon at con_deinit callback.  Since the code to adjust the attrs is
> > >> already present in the current fbcon code, in this patch, we simply
> > >> factor out the relevant code, and call it from fbcon_deinit().
> > >>
> > >> Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1000619
> > >> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > > 
> > > Actually not only checkpatch but also I can't find the proper
> > > maintainer for this...
> > > 
> > > Tomi, could you check and take if it's OK?
> > > 
> > > Ideally, this kind of stuff should have been in rather vt side, I
> > > suppose.  But since the code is already present in fbcon, it's easier
> > > to reuse it as a fix for now.
> > 
> > I'm not fbdev maintainer anymore. Added Bartlomiej (and Andrew).
> 
> Bartlomiej (or Andrew), could you check the patch?  In case you missed
> it, I attach it below again.

Thanks, it is on TODO (should be processed till the end of the week).

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> thanks,
> 
> Takashi
> 
> -- 8< --
> From: Takashi Iwai <tiwai@...e.de>
> Subject: [PATCH] fbcon: Fix vc attr at deinit
> 
> fbcon can deal with vc_hi_font_mask (the upper 256 chars) and adjust
> the vc attrs dynamically when vc_hi_font_mask is changed at
> fbcon_init().  When the vc_hi_font_mask is set, it remaps the attrs in
> the existing console buffer with one bit shift up (for 9 bits), while
> it remaps with one bit shift down (for 8 bits) when the value is
> cleared.  It works fine as long as the font gets updated after fbcon
> was initialized.
> 
> However, we hit a bizarre problem when the console is switched to
> another fb driver (typically from vesafb or efifb to drmfb).  At
> switching to the new fb driver, we temporarily rebind the console to
> the dummy console, then rebind to the new driver.  During the
> switching, we leave the modified attrs as is.  Thus, the new fbcon
> takes over the old buffer as if it were to contain 8 bits chars
> (although the attrs are still shifted for 9 bits), and effectively
> this results in the yellow color texts instead of the original white
> color, as found in the bugzilla entry below.
> 
> An easy fix for this is to re-adjust the attrs before leaving the
> fbcon at con_deinit callback.  Since the code to adjust the attrs is
> already present in the current fbcon code, in this patch, we simply
> factor out the relevant code, and call it from fbcon_deinit().
> 
> Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1000619
> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> ---
>  drivers/video/console/fbcon.c | 67 ++++++++++++++++++++++++++-----------------
>  1 file changed, 40 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> index a44f5627b82a..f4daadff8a6c 100644
> --- a/drivers/video/console/fbcon.c
> +++ b/drivers/video/console/fbcon.c
> @@ -1165,6 +1165,8 @@ static void fbcon_free_font(struct display *p, bool freefont)
>  	p->userfont = 0;
>  }
>  
> +static void set_vc_hi_font(struct vc_data *vc, bool set);
> +
>  static void fbcon_deinit(struct vc_data *vc)
>  {
>  	struct display *p = &fb_display[vc->vc_num];
> @@ -1200,6 +1202,9 @@ static void fbcon_deinit(struct vc_data *vc)
>  	if (free_font)
>  		vc->vc_font.data = NULL;
>  
> +	if (vc->vc_hi_font_mask)
> +		set_vc_hi_font(vc, false);
> +
>  	if (!con_is_bound(&fb_con))
>  		fbcon_exit();
>  
> @@ -2436,32 +2441,10 @@ static int fbcon_get_font(struct vc_data *vc, struct console_font *font)
>  	return 0;
>  }
>  
> -static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
> -			     const u8 * data, int userfont)
> +/* set/clear vc_hi_font_mask and update vc attrs accordingly */
> +static void set_vc_hi_font(struct vc_data *vc, bool set)
>  {
> -	struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
> -	struct fbcon_ops *ops = info->fbcon_par;
> -	struct display *p = &fb_display[vc->vc_num];
> -	int resize;
> -	int cnt;
> -	char *old_data = NULL;
> -
> -	if (con_is_visible(vc) && softback_lines)
> -		fbcon_set_origin(vc);
> -
> -	resize = (w != vc->vc_font.width) || (h != vc->vc_font.height);
> -	if (p->userfont)
> -		old_data = vc->vc_font.data;
> -	if (userfont)
> -		cnt = FNTCHARCNT(data);
> -	else
> -		cnt = 256;
> -	vc->vc_font.data = (void *)(p->fontdata = data);
> -	if ((p->userfont = userfont))
> -		REFCOUNT(data)++;
> -	vc->vc_font.width = w;
> -	vc->vc_font.height = h;
> -	if (vc->vc_hi_font_mask && cnt == 256) {
> +	if (!set) {
>  		vc->vc_hi_font_mask = 0;
>  		if (vc->vc_can_do_color) {
>  			vc->vc_complement_mask >>= 1;
> @@ -2484,7 +2467,7 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
>  			    ((c & 0xfe00) >> 1) | (c & 0xff);
>  			vc->vc_attr >>= 1;
>  		}
> -	} else if (!vc->vc_hi_font_mask && cnt == 512) {
> +	} else {
>  		vc->vc_hi_font_mask = 0x100;
>  		if (vc->vc_can_do_color) {
>  			vc->vc_complement_mask <<= 1;
> @@ -2516,8 +2499,38 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
>  			} else
>  				vc->vc_video_erase_char = c & ~0x100;
>  		}
> -
>  	}
> +}
> +
> +static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
> +			     const u8 * data, int userfont)
> +{
> +	struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
> +	struct fbcon_ops *ops = info->fbcon_par;
> +	struct display *p = &fb_display[vc->vc_num];
> +	int resize;
> +	int cnt;
> +	char *old_data = NULL;
> +
> +	if (con_is_visible(vc) && softback_lines)
> +		fbcon_set_origin(vc);
> +
> +	resize = (w != vc->vc_font.width) || (h != vc->vc_font.height);
> +	if (p->userfont)
> +		old_data = vc->vc_font.data;
> +	if (userfont)
> +		cnt = FNTCHARCNT(data);
> +	else
> +		cnt = 256;
> +	vc->vc_font.data = (void *)(p->fontdata = data);
> +	if ((p->userfont = userfont))
> +		REFCOUNT(data)++;
> +	vc->vc_font.width = w;
> +	vc->vc_font.height = h;
> +	if (vc->vc_hi_font_mask && cnt == 256)
> +		set_vc_hi_font(vc, false);
> +	else if (!vc->vc_hi_font_mask && cnt == 512)
> +		set_vc_hi_font(vc, true);
>  
>  	if (resize) {
>  		int cols, rows;

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