linux-kernel - Re: [PATCH 1/6] efi: earlycon: Reduce number of references to global screen

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Message-ID: <aSQlUVPfQrEwXPWm@r1chard>
Date: Mon, 24 Nov 2025 17:28:49 +0800
From: Richard Lyu <richard.lyu@...e.com>
To: Thomas Zimmermann <tzimmermann@...e.de>, ardb@...nel.org,
	javierm@...hat.com, arnd@...db.de
Cc: x86@...nel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	loongarch@...ts.linux.dev, linux-riscv@...ts.infradead.org,
	dri-devel@...ts.freedesktop.org, linux-hyperv@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH 1/6] efi: earlycon: Reduce number of references to global
 screen_info

Reviewed-by: Richard Lyu <richard.lyu@...e.com>

On 2025/11/21 14:36, Thomas Zimmermann wrote:
> Replace usage of global screen_info with local pointers. This will
> later reduce churn when screen_info is being moved.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
> ---
>  drivers/firmware/efi/earlycon.c | 40 ++++++++++++++++-----------------
>  1 file changed, 20 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c
> index d18a1a5de144..fac3a295c57f 100644
> --- a/drivers/firmware/efi/earlycon.c
> +++ b/drivers/firmware/efi/earlycon.c
> @@ -32,12 +32,13 @@ static void *efi_fb;
>   */
>  static int __init efi_earlycon_remap_fb(void)
>  {
> +	const struct screen_info *si = &screen_info;
> +
>  	/* bail if there is no bootconsole or it was unregistered already */
>  	if (!earlycon_console || !console_is_registered(earlycon_console))
>  		return 0;
>  
> -	efi_fb = memremap(fb_base, screen_info.lfb_size,
> -			  fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
> +	efi_fb = memremap(fb_base, si->lfb_size, fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
>  
>  	return efi_fb ? 0 : -ENOMEM;
>  }
> @@ -71,12 +72,12 @@ static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
>  	early_memunmap(addr, len);
>  }
>  
> -static void efi_earlycon_clear_scanline(unsigned int y)
> +static void efi_earlycon_clear_scanline(unsigned int y, const struct screen_info *si)
>  {
>  	unsigned long *dst;
>  	u16 len;
>  
> -	len = screen_info.lfb_linelength;
> +	len = si->lfb_linelength;
>  	dst = efi_earlycon_map(y*len, len);
>  	if (!dst)
>  		return;
> @@ -85,7 +86,7 @@ static void efi_earlycon_clear_scanline(unsigned int y)
>  	efi_earlycon_unmap(dst, len);
>  }
>  
> -static void efi_earlycon_scroll_up(void)
> +static void efi_earlycon_scroll_up(const struct screen_info *si)
>  {
>  	unsigned long *dst, *src;
>  	u16 maxlen = 0;
> @@ -99,8 +100,8 @@ static void efi_earlycon_scroll_up(void)
>  	}
>  	maxlen *= 4;
>  
> -	len = screen_info.lfb_linelength;
> -	height = screen_info.lfb_height;
> +	len = si->lfb_linelength;
> +	height = si->lfb_height;
>  
>  	for (i = 0; i < height - font->height; i++) {
>  		dst = efi_earlycon_map(i*len, len);
> @@ -120,7 +121,8 @@ static void efi_earlycon_scroll_up(void)
>  	}
>  }
>  
> -static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
> +static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h,
> +				    const struct screen_info *si)
>  {
>  	const u32 color_black = 0x00000000;
>  	const u32 color_white = 0x00ffffff;
> @@ -145,13 +147,12 @@ static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
>  static void
>  efi_earlycon_write(struct console *con, const char *str, unsigned int num)
>  {
> -	struct screen_info *si;
> +	const struct screen_info *si = &screen_info;
>  	u32 cur_efi_x = efi_x;
>  	unsigned int len;
>  	const char *s;
>  	void *dst;
>  
> -	si = &screen_info;
>  	len = si->lfb_linelength;
>  
>  	while (num) {
> @@ -174,7 +175,7 @@ efi_earlycon_write(struct console *con, const char *str, unsigned int num)
>  			x = efi_x;
>  
>  			while (n-- > 0) {
> -				efi_earlycon_write_char(dst + x*4, *s, h);
> +				efi_earlycon_write_char(dst + x*4, *s, h, si);
>  				x += font->width;
>  				s++;
>  			}
> @@ -207,10 +208,10 @@ efi_earlycon_write(struct console *con, const char *str, unsigned int num)
>  			cur_line_y = (cur_line_y + 1) % max_line_y;
>  
>  			efi_y -= font->height;
> -			efi_earlycon_scroll_up();
> +			efi_earlycon_scroll_up(si);
>  
>  			for (i = 0; i < font->height; i++)
> -				efi_earlycon_clear_scanline(efi_y + i);
> +				efi_earlycon_clear_scanline(efi_y + i, si);
>  		}
>  	}
>  }
> @@ -226,22 +227,21 @@ void __init efi_earlycon_reprobe(void)
>  static int __init efi_earlycon_setup(struct earlycon_device *device,
>  				     const char *opt)
>  {
> -	struct screen_info *si;
> +	const struct screen_info *si = &screen_info;
>  	u16 xres, yres;
>  	u32 i;
>  
>  	fb_wb = opt && !strcmp(opt, "ram");
>  
> -	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI) {
> +	if (si->orig_video_isVGA != VIDEO_TYPE_EFI) {
>  		fb_probed = true;
>  		return -ENODEV;
>  	}
>  
> -	fb_base = screen_info.lfb_base;
> -	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
> -		fb_base |= (u64)screen_info.ext_lfb_base << 32;
> +	fb_base = si->lfb_base;
> +	if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
> +		fb_base |= (u64)si->ext_lfb_base << 32;
>  
> -	si = &screen_info;
>  	xres = si->lfb_width;
>  	yres = si->lfb_height;
>  
> @@ -266,7 +266,7 @@ static int __init efi_earlycon_setup(struct earlycon_device *device,
>  
>  	efi_y -= font->height;
>  	for (i = 0; i < (yres - efi_y) / font->height; i++)
> -		efi_earlycon_scroll_up();
> +		efi_earlycon_scroll_up(si);
>  
>  	device->con->write = efi_earlycon_write;
>  	earlycon_console = device->con;
> -- 
> 2.51.1
> 
>