Re: [PATCH v2 5/9] vgacon: remove screen_info dependency

Philippe Mathieu-Daudé
2023-07-19T13:50:06Z

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;
> +}