Re: [PATCH v2 07/13] lib/fonts: Store font data as font_data_t; update consoles

[Helge Deller <deller@gmx.de>]

On 3/2/26 15:08, Thomas Zimmermann wrote:
> Store font data as pointer to font_data_t instead of unsigned char.
> Update consoles.
> 
> Pointers to font data refer to the raw data. There is a hidden header
> before the data that contains additional state. Document the existing
> layout and semantics of font_data_t.
> 
> The data field in struct vc_font can be used by any console. Therefore
> it still points to plain data without the additional header. Fbcon sets
> its value from struct fbcon_display.fontdata. Hence, update the size
> test in fbcon_resize() to use struct fbcon_display.fontdata instead of
> struct vc_font.data.
> 
> v2:
> - 'Font lookup' -> 'Font description' in <linux/font.h>
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>   drivers/video/console/newport_con.c | 17 ++++++-----
>   drivers/video/fbdev/core/fbcon.c    | 44 ++++++++++++++++-----------
>   drivers/video/fbdev/core/fbcon.h    |  3 +-
>   include/linux/font.h                | 47 ++++++++++++++++++++++++++++-
>   4 files changed, 84 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
> index e2922caa8685..9b9ed1940404 100644
> --- a/drivers/video/console/newport_con.c
> +++ b/drivers/video/console/newport_con.c
> @@ -33,9 +33,9 @@
>   
>   #define NEWPORT_LEN	0x10000
>   
> -#define FONT_DATA ((unsigned char *)font_vga_8x16.data)
> +#define FONT_DATA font_vga_8x16.data
>   
> -static unsigned char *font_data[MAX_NR_CONSOLES];
> +static font_data_t *font_data[MAX_NR_CONSOLES];
>   
>   static struct newport_regs *npregs;
>   static unsigned long newport_addr;
> @@ -370,9 +370,9 @@ static void newport_clear(struct vc_data *vc, unsigned int sy, unsigned int sx,
>   static void newport_putc(struct vc_data *vc, u16 charattr, unsigned int ypos,
>   			 unsigned int xpos)
>   {
> -	unsigned char *p;
> +	const unsigned char *p;
>   
> -	p = &font_data[vc->vc_num][(charattr & 0xff) << 4];
> +	p = &font_data_buf(font_data[vc->vc_num])[(charattr & 0xff) << 4];
>   	charattr = (charattr >> 8) & 0xff;
>   	xpos <<= 3;
>   	ypos <<= 4;
> @@ -400,7 +400,7 @@ static void newport_putcs(struct vc_data *vc, const u16 *s,
>   			  unsigned int count, unsigned int ypos,
>   			  unsigned int xpos)
>   {
> -	unsigned char *p;
> +	const unsigned char *p;
>   	unsigned int i;
>   	u16 charattr;
>   
> @@ -424,7 +424,7 @@ static void newport_putcs(struct vc_data *vc, const u16 *s,
>   				 NPORT_DMODE0_L32);
>   
>   	for (i = 0; i < count; i++, xpos += 8) {
> -		p = &font_data[vc->vc_num][(scr_readw(s++) & 0xff) << 4];
> +		p = &font_data_buf(font_data[vc->vc_num])[(scr_readw(s++) & 0xff) << 4];
>   
>   		newport_wait(npregs);
>   
> @@ -503,7 +503,8 @@ static int newport_set_font(int unit, const struct console_font *op,
>   	int h = op->height;
>   	int size = h * op->charcount;
>   	int i;
> -	unsigned char *new_data, *data = op->data, *p;
> +	font_data_t *new_data;
> +	unsigned char *data = op->data, *p;
>   
>   	/* ladis: when I grow up, there will be a day... and more sizes will
>   	 * be supported ;-) */
> @@ -519,7 +520,7 @@ static int newport_set_font(int unit, const struct console_font *op,
>   	REFCOUNT(new_data) = 0;	/* usage counter */
>   	FNTSUM(new_data) = 0;
>   
> -	p = new_data;
> +	p = (unsigned char *)font_data_buf(new_data);
>   	for (i = 0; i < op->charcount; i++) {
>   		memcpy(p, data, h);
>   		data += 32;
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 103e91c8d874..8d7840b9ebad 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -1019,8 +1019,10 @@ static const char *fbcon_startup(void)
>   						info->pixmap.blit_y);
>   		vc->vc_font.width = font->width;
>   		vc->vc_font.height = font->height;
> -		vc->vc_font.data = (void *)(p->fontdata = font->data);
> +		vc->vc_font.data = font_data_buf(font->data);
>   		vc->vc_font.charcount = font->charcount;
> +
> +		p->fontdata = font->data;
>   	}
>   
>   	cols = FBCON_SWAP(par->rotate, info->var.xres, info->var.yres);
> @@ -1078,11 +1080,12 @@ static void fbcon_init(struct vc_data *vc, bool init)
>   		if (t->fontdata) {
>   			struct vc_data *fvc = vc_cons[fg_console].d;
>   
> -			vc->vc_font.data = (void *)(p->fontdata =
> -						    fvc->vc_font.data);
> +			vc->vc_font.data = fvc->vc_font.data;
>   			vc->vc_font.width = fvc->vc_font.width;
>   			vc->vc_font.height = fvc->vc_font.height;
>   			vc->vc_font.charcount = fvc->vc_font.charcount;
> +
> +			p->fontdata = t->fontdata;
>   			p->userfont = t->userfont;
>   
>   			if (p->userfont)
> @@ -1097,8 +1100,10 @@ static void fbcon_init(struct vc_data *vc, bool init)
>   							info->pixmap.blit_y);
>   			vc->vc_font.width = font->width;
>   			vc->vc_font.height = font->height;
> -			vc->vc_font.data = (void *)(p->fontdata = font->data);
> +			vc->vc_font.data = font_data_buf(font->data);
>   			vc->vc_font.charcount = font->charcount;
> +
> +			p->fontdata = font->data;
>   		}
>   	}
>   
> @@ -1409,11 +1414,12 @@ static void fbcon_set_disp(struct fb_info *info, struct fb_var_screeninfo *var,
>   	svc = *default_mode;
>   	t = &fb_display[svc->vc_num];
>   
> -	if (!vc->vc_font.data) {
> -		vc->vc_font.data = (void *)(p->fontdata = t->fontdata);
> +	if (!p->fontdata) {
> +		vc->vc_font.data = font_data_buf(t->fontdata);
>   		vc->vc_font.width = (*default_mode)->vc_font.width;
>   		vc->vc_font.height = (*default_mode)->vc_font.height;
>   		vc->vc_font.charcount = (*default_mode)->vc_font.charcount;
> +		p->fontdata = t->fontdata;
>   		p->userfont = t->userfont;
>   		if (p->userfont)
>   			REFCOUNT(p->fontdata)++;
> @@ -2047,7 +2053,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width,
>   	struct fb_var_screeninfo var = info->var;
>   	int x_diff, y_diff, virt_w, virt_h, virt_fw, virt_fh;
>   
> -	if (p->userfont && FNTSIZE(vc->vc_font.data)) {
> +	if (p->userfont && FNTSIZE(p->fontdata)) {
>   		unsigned int size = vc_font_size(&vc->vc_font);
>   
>   		/*
> @@ -2057,7 +2063,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width,
>   		 * charcount can change and cannot be used to determine the
>   		 * font data allocated size.
>   		 */
> -		if (!size || size > FNTSIZE(vc->vc_font.data))
> +		if (!size || size > FNTSIZE(p->fontdata))
>   			return -EINVAL;
>   	}
>   
> @@ -2281,7 +2287,8 @@ static bool fbcon_blank(struct vc_data *vc, enum vesa_blank_mode blank,
>   
>   static int fbcon_get_font(struct vc_data *vc, struct console_font *font, unsigned int vpitch)
>   {
> -	const u8 *fontdata = vc->vc_font.data;
> +	struct fbcon_display *p = &fb_display[vc->vc_num];
> +	font_data_t *fontdata = p->fontdata;
>   	u8 *data = font->data;
>   	int i, j;
>   
> @@ -2406,16 +2413,18 @@ static void set_vc_hi_font(struct vc_data *vc, bool set)
>   }
>   
>   static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount,
> -			     const u8 * data, int userfont)
> +			     font_data_t *data, int userfont)
>   {
>   	struct fb_info *info = fbcon_info_from_console(vc->vc_num);
>   	struct fbcon_par *par = info->fbcon_par;
>   	struct fbcon_display *p = &fb_display[vc->vc_num];
>   	int resize, ret, old_userfont, old_width, old_height, old_charcount;
> +	font_data_t *old_fontdata = p->fontdata;
>   	const u8 *old_data = vc->vc_font.data;
>   
>   	resize = (w != vc->vc_font.width) || (h != vc->vc_font.height);
> -	vc->vc_font.data = (void *)(p->fontdata = data);
> +	p->fontdata = data;
> +	vc->vc_font.data = font_data_buf(p->fontdata);
>   	old_userfont = p->userfont;
>   	if ((p->userfont = userfont))
>   		REFCOUNT(data)++;
> @@ -2448,12 +2457,12 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount,
>   		update_screen(vc);
>   	}
>   
> -	if (old_userfont && (--REFCOUNT(old_data) == 0))
> -		kfree(old_data - FONT_EXTRA_WORDS * sizeof(int));
> +	if (old_userfont && (--REFCOUNT(old_fontdata) == 0))
> +		kfree(old_fontdata - FONT_EXTRA_WORDS * sizeof(int));
>   	return 0;
>   
>   err_out:
> -	p->fontdata = old_data;
> +	p->fontdata = old_fontdata;
>   	vc->vc_font.data = old_data;
>   
>   	if (userfont) {
> @@ -2483,7 +2492,8 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font,
>   	int h = font->height;
>   	int size, alloc_size;
>   	int i, csum;
> -	u8 *new_data, *data = font->data;
> +	font_data_t *new_data;
> +	u8 *data = font->data;
>   	int pitch = PITCH(font->width);
>   
>   	/* Is there a reason why fbconsole couldn't handle any charcount >256?
> @@ -2522,13 +2532,13 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font,
>   	if (!new_data)
>   		return -ENOMEM;
>   
> -	memset(new_data, 0, FONT_EXTRA_WORDS * sizeof(int));
> +	memset((u8 *)new_data, 0, FONT_EXTRA_WORDS * sizeof(int));
>   
>   	new_data += FONT_EXTRA_WORDS * sizeof(int);
>   	FNTSIZE(new_data) = size;
>   	REFCOUNT(new_data) = 0;	/* usage counter */
>   	for (i=0; i< charcount; i++) {
> -		memcpy(new_data + i*h*pitch, data +  i*vpitch*pitch, h*pitch);
> +		memcpy((u8 *)new_data + i * h * pitch, data + i * vpitch * pitch, h * pitch);
>   	}
>   
>   	/* Since linux has a nice crc32 function use it for counting font
> diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h
> index 3f4386a40237..d26ee7860cf5 100644
> --- a/drivers/video/fbdev/core/fbcon.h
> +++ b/drivers/video/fbdev/core/fbcon.h
> @@ -11,6 +11,7 @@
>   #ifndef _VIDEO_FBCON_H
>   #define _VIDEO_FBCON_H
>   
> +#include <linux/font.h>
>   #include <linux/types.h>
>   #include <linux/vt_buffer.h>
>   #include <linux/vt_kern.h>
> @@ -25,7 +26,7 @@
>   
>   struct fbcon_display {
>       /* Filled in by the low-level console driver */
> -    const u_char *fontdata;
> +    font_data_t *fontdata;
>       int userfont;                   /* != 0 if fontdata kmalloc()ed */
>   #ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>       u_short scrollmode;             /* Scroll Method, use fb_scrollmode() */
> diff --git a/include/linux/font.h b/include/linux/font.h
> index d929c5fa32ca..f19abd112c18 100644
> --- a/include/linux/font.h
> +++ b/include/linux/font.h
> @@ -13,12 +13,57 @@
>   
>   #include <linux/types.h>
>   
> +/*
> + * font_data_t and helpers
> + */
> +
> +/**
> + * font_data_t - Raw font data
> + *
> + * Values of type font_data_t store a pointer to raw font data. The format
> + * is monochrome. Each bit sets a pixel of a stored glyph. Font data does
> + * not store geometry information for the individual glyphs. Users of the
> + * font have to store glyph size, pitch and characer count separately.
> + *
> + * Font data in font_data_t is not equivalent to raw u8. Each pointer stores
> + * an additional hidden header before the fotn data. The layout is

typo: fotn -> font


>   struct font_desc {
>       int idx;
>       const char *name;
>       unsigned int width, height;
>       unsigned int charcount;

FYI - maybe type of width, height, charcount would need update here if it's
changed as I proposed in the other patch?

Helge