linux-kernel - Re: [PATCH] fbcon: Increase maximum font width x height to 64 x 64

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Message-ID: <d7ca4ae3-4bcc-49f0-a819-4ad88907b93c@gmx.de>
Date: Fri, 15 Mar 2024 10:35:40 +0100
From: Helge Deller <deller@....de>
To: Samuel Thibault <samuel.thibault@...-lyon.org>,
 linux-kernel@...r.kernel.org, Daniel Vetter <daniel@...ll.ch>,
 Alexey Gladkov <legion@...nel.org>, Jiry Slaby <jirislaby@...nel.org>
Cc: linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] fbcon: Increase maximum font width x height to 64 x 64

You should have marked this patch with "v2"...

On 3/13/24 17:59, Samuel Thibault wrote:
> This remains relatively simple by just enlarging integers.

I like the patch, but I still see some u32...
drivers/video/fbdev/vt8623fb.c:         info->pixmap.blit_x = (bpp == 4) ? (1 << (8 - 1)) : (~(u32)0);
drivers/video/fbdev/arkfb.c:            info->pixmap.blit_x = (bpp == 4) ? (1 << (8 - 1)) : (~(u32)0);
drivers/video/fbdev/core/fbmem.c:               fb_info->pixmap.blit_x = ~(u32)0;
drivers/video/fbdev/s3fb.c:             info->pixmap.blit_x = (bpp == 4) ? (1 << (8 - 1)) : (~(u32)0);

And please check blit_y too.

> It wouldn't be that simple to get to the console's 64x128 maximum, as it would
> require 128b integers.

How realistic are fonts > 64x64 pixels ?
If they are, using the bitmap_xx functions (include/linux/bitmap.h)
now instead would be better.

Helge

> Signed-off-by: Samuel Thibault <samuel.thibault@...-lyon.org>
> ---
>   drivers/video/fbdev/core/fbcon.c | 17 ++++++++++-------
>   include/linux/fb.h               | 10 +++++-----
>   2 files changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 46823c2e2ba1..849562f92bd5 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -101,6 +101,9 @@ enum {
>   	FBCON_LOGO_DONTSHOW	= -3	/* do not show the logo */
>   };
>
> +#define FBCON_MAX_FONT_WIDTH	(sizeof(((struct fb_pixmap *) 0)->blit_x) * 8)
> +#define FBCON_MAX_FONT_HEIGHT	(sizeof(((struct fb_pixmap *) 0)->blit_y) * 8)
> +
>   static struct fbcon_display fb_display[MAX_NR_CONSOLES];
>
>   static struct fb_info *fbcon_registered_fb[FB_MAX];
> @@ -2483,12 +2486,12 @@ static int fbcon_set_font(struct vc_data *vc, struct console_font *font,
>   	    h > FBCON_SWAP(info->var.rotate, info->var.yres, info->var.xres))
>   		return -EINVAL;
>
> -	if (font->width > 32 || font->height > 32)
> +	if (font->width > FBCON_MAX_FONT_WIDTH || font->height > FBCON_MAX_FONT_HEIGHT)
>   		return -EINVAL;
>
>   	/* Make sure drawing engine can handle the font */
> -	if (!(info->pixmap.blit_x & BIT(font->width - 1)) ||
> -	    !(info->pixmap.blit_y & BIT(font->height - 1)))
> +	if (!(info->pixmap.blit_x & BIT_ULL(font->width - 1)) ||
> +	    !(info->pixmap.blit_y & BIT_ULL(font->height - 1)))
>   		return -EINVAL;
>
>   	/* Make sure driver can handle the font length */
> @@ -3082,8 +3085,8 @@ void fbcon_get_requirement(struct fb_info *info,
>   			vc = vc_cons[i].d;
>   			if (vc && vc->vc_mode == KD_TEXT &&
>   			    info->node == con2fb_map[i]) {
> -				caps->x |= 1 << (vc->vc_font.width - 1);
> -				caps->y |= 1 << (vc->vc_font.height - 1);
> +				caps->x |= 1ULL << (vc->vc_font.width - 1);
> +				caps->y |= 1ULL << (vc->vc_font.height - 1);
>   				charcnt = vc->vc_font.charcount;
>   				if (caps->len < charcnt)
>   					caps->len = charcnt;
> @@ -3094,8 +3097,8 @@ void fbcon_get_requirement(struct fb_info *info,
>
>   		if (vc && vc->vc_mode == KD_TEXT &&
>   		    info->node == con2fb_map[fg_console]) {
> -			caps->x = 1 << (vc->vc_font.width - 1);
> -			caps->y = 1 << (vc->vc_font.height - 1);
> +			caps->x = 1ULL << (vc->vc_font.width - 1);
> +			caps->y = 1ULL << (vc->vc_font.height - 1);
>   			caps->len = vc->vc_font.charcount;
>   		}
>   	}
> diff --git a/include/linux/fb.h b/include/linux/fb.h
> index 05dc9624897d..2bac166cd3f2 100644
> --- a/include/linux/fb.h
> +++ b/include/linux/fb.h
> @@ -144,8 +144,8 @@ struct fb_event {
>   };
>
>   struct fb_blit_caps {
> -	u32 x;
> -	u32 y;
> +	u64 x;
> +	u64 y;
>   	u32 len;
>   	u32 flags;
>   };
> @@ -192,10 +192,10 @@ struct fb_pixmap {
>   	u32 scan_align;		/* alignment per scanline		*/
>   	u32 access_align;	/* alignment per read/write (bits)	*/
>   	u32 flags;		/* see FB_PIXMAP_*			*/
> -	u32 blit_x;             /* supported bit block dimensions (1-32)*/
> -	u32 blit_y;             /* Format: blit_x = 1 << (width - 1)    */
> +	u64 blit_x;             /* supported bit block dimensions (1-64)*/
> +	u64 blit_y;             /* Format: blit_x = 1 << (width - 1)    */
>   	                        /*         blit_y = 1 << (height - 1)   */
> -	                        /* if 0, will be set to 0xffffffff (all)*/
> +	                        /* if 0, will be set to ~0ull (all)     */
>   	/* access methods */
>   	void (*writeio)(struct fb_info *info, void __iomem *dst, void *src, unsigned int size);
>   	void (*readio) (struct fb_info *info, void *dst, void __iomem *src, unsigned int size);