Re: [PATCH] fbcon: Fix vc attr at deinit

[Bartlomiej Zolnierkiewicz]

Hi,

On Tuesday, January 10, 2017 05:09:43 PM Bartlomiej Zolnierkiewicz wrote:
> 
> 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@xxxxxxx>
> > > > 
> > > > 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).

Patch queued for 4.11, thanks.

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

> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
> 
> > thanks,
> > 
> > Takashi
> > 
> > -- 8< --
> > From: Takashi Iwai <tiwai@xxxxxxx>
> > 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@xxxxxxx>
> > ---
> >  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;