linux-kernel - Re: [patch 1/3] VT: Add height parameter to con_font

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Date:   Tue, 6 Dec 2022 07:40:30 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Samuel Thibault <samuel.thibault@...-lyon.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kbd@...ts.altlinux.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [patch 1/3] VT: Add height parameter to con_font_get/set consw
 operations

On 05. 12. 22, 1:07, Samuel Thibault wrote:
> The current con_font_get/set API currently hardcodes a 32-pixel-tall
> limitation, which only dates from the old VGA hardware which could not
> handle taller fonts than that.
> 
> This change just adds a vpitch parameter to release this
> constraint. Drivers which do not support vpitch != 32 can just return
> EINVAL when it is not 32, font loading tools will revert to trying 32
> and succeed.
> 
> This change makes the fbcon driver consider vpitch appropriately, thus
> making it able to load large fonts.
> 
> Signed-off-by: Samuel Thibault <samuel.thibault@...-lyon.org>
> 
...
> --- linux-6.0.orig/drivers/usb/misc/sisusbvga/sisusb_con.c
> +++ linux-6.0/drivers/usb/misc/sisusbvga/sisusb_con.c
...
> @@ -1243,13 +1244,15 @@ sisusbcon_font_set(struct vc_data *c, st
>   
>   /* Interface routine */
>   static int
> -sisusbcon_font_get(struct vc_data *c, struct console_font *font)
> +sisusbcon_font_get(struct vc_data *c, struct console_font *font, unsigned int vpitch)
>   {
>   	struct sisusb_usb_data *sisusb;
>   
>   	sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
>   	if (!sisusb)
>   		return -ENODEV;
> +	if (vpitch != 32)
> +		return -EINVAL;
>   
>   	/* sisusb->lock is down */
>   
> @@ -1268,7 +1271,7 @@ sisusbcon_font_get(struct vc_data *c, st
>   	}
>   
>   	/* Copy 256 chars only, like vgacon */
> -	memcpy(font->data, sisusb->font_backup, 256 * 32);
> +	memcpy(font->data, sisusb->font_backup, 256 * height);

Have you tested this? What does this 'height' refer to?

thanks,
-- 
js
suse labs