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Message-ID: <32595080-dd79-5cf0-46e7-b82d0df8f067@linaro.org>
Date:   Wed, 19 Jul 2023 15:49:22 +0200
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Subject: Re: [PATCH v2 5/9] vgacon: remove screen_info dependency
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To:     Arnd Bergmann <arnd@kernel.org>, linux-fbdev@vger.kernel.org,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Helge Deller <deller@gmx.de>,
        Javier Martinez Canillas <javierm@redhat.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        "David S. Miller" <davem@davemloft.net>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Borislav Petkov <bp@alien8.de>, Brian Cain <bcain@quicinc.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Daniel Vetter <daniel@ffwll.ch>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        David Airlie <airlied@gmail.com>,
        Deepak Rawat <drawat.floss@gmail.com>,
        Dexuan Cui <decui@microsoft.com>,
        Dinh Nguyen <dinguyen@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Guo Ren <guoren@kernel.org>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        Khalid Aziz <khalid@gonehiking.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Matt Turner <mattst88@gmail.com>,
        Max Filippov <jcmvbkbc@gmail.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Russell King <linux@armlinux.org.uk>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        WANG Xuerui <kernel@xen0n.name>, Wei Liu <wei.liu@kernel.org>,
        Will Deacon <will@kernel.org>, x86@kernel.org,
        linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org,
        linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org,
        linux-ia64@vger.kernel.org, loongarch@lists.linux.dev,
        linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org,
        sparclinux@vger.kernel.org, linux-hyperv@vger.kernel.org,
        dri-devel@lists.freedesktop.org
References: <20230719123944.3438363-1-arnd@kernel.org>
 <20230719123944.3438363-6-arnd@kernel.org>
From:   =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= <philmd@linaro.org>
In-Reply-To: <20230719123944.3438363-6-arnd@kernel.org>
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Hi Arnd,

On 19/7/23 14:39, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The vga console driver is fairly self-contained, and only used by
> architectures that explicitly initialize the screen_info settings.
> 
> Chance every instance that picks the vga console by setting conswitchp
> to call a function instead, and pass a reference to the screen_info
> there.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   arch/alpha/kernel/setup.c      |  2 +-
>   arch/arm/kernel/setup.c        |  2 +-
>   arch/ia64/kernel/setup.c       |  2 +-
>   arch/mips/kernel/setup.c       |  2 +-
>   arch/x86/kernel/setup.c        |  2 +-
>   drivers/firmware/pcdp.c        |  2 +-
>   drivers/video/console/vgacon.c | 68 ++++++++++++++++++++--------------
>   include/linux/console.h        |  7 ++++
>   8 files changed, 53 insertions(+), 34 deletions(-)


> @@ -1074,13 +1077,13 @@ static int vgacon_resize(struct vc_data *c, unsigned int width,
>   		 * Ho ho!  Someone (svgatextmode, eh?) may have reprogrammed
>   		 * the video mode!  Set the new defaults then and go away.
>   		 */
> -		screen_info.orig_video_cols = width;
> -		screen_info.orig_video_lines = height;
> +		vga_si->orig_video_cols = width;
> +		vga_si->orig_video_lines = height;
>   		vga_default_font_height = c->vc_cell_height;
>   		return 0;
>   	}
> -	if (width % 2 || width > screen_info.orig_video_cols ||
> -	    height > (screen_info.orig_video_lines * vga_default_font_height)/
> +	if (width % 2 || width > vga_si->orig_video_cols ||
> +	    height > (vga_si->orig_video_lines * vga_default_font_height)/
>   	    c->vc_cell_height)
>   		return -EINVAL;
>   
> @@ -1110,8 +1113,8 @@ static void vgacon_save_screen(struct vc_data *c)
>   		 * console initialization routines.
>   		 */
>   		vga_bootup_console = 1;
> -		c->state.x = screen_info.orig_x;
> -		c->state.y = screen_info.orig_y;
> +		c->state.x = vga_si->orig_x;
> +		c->state.y = vga_si->orig_y;

Not really my area, so bare with me if this is obviously not
possible :) If using DUMMY_CONSOLE, can we trigger a save_screen
/ resize? If so, we'd reach here with vga_si=NULL.

>   	}
>   
>   	/* We can't copy in more than the size of the video buffer,
> @@ -1204,4 +1207,13 @@ const struct consw vga_con = {
>   };
>   EXPORT_SYMBOL(vga_con);
>   
> +void vgacon_register_screen(struct screen_info *si)
> +{
> +	if (!si || vga_si)
> +		return;
> +
> +	conswitchp = &vga_con;
> +	vga_si = si;
> +}