Re: [PATCH 2/2] vt: Distinguish between blanking and VESA blank mode in con_blank

[sashiko-bot@kernel.org]

> The con_blank callback in struct consw encodes blanking and display
> blank mode in a single parameter named blank. Its semantics equal
> the FB_BLANK constants from the fbdev subsystems. Yet it is of type
> enum vesa_blank_mode, which describes VESA DPMS levels of the attached
> monitor. Although related, this is something else.
> 
> For this reason, calls to con_blank fill the blank parameter with
> values that appear non-sensical at first. For example, to blank the
> console, but keep the monitor on, vt passes VESA_VSYNC_SUSPEND (eq '1').
> This is because consoles interpret '1' as pixels-off-but-monitor-on.
> The constant VESA_VSYNC_SUSPEND actually means monitor-vsync-off. And
> the argument used for monitor-vsync-off is VESA_VSYNC_SUSPEND+1.
> 
> To fix this by splitting blank into two parameters, blank and blank_mode.
> The new blank is a boolean to control the display blanking. If cleared,
> the console creates display output, if set the console does not. The
> new parameter blank_mode specifies the VESA blank mode for the monitor
> and equals VESA DPMS levels. If blank is set, blank_mode gives a hint
> to the console, on how to set up the signal to the monitor.
> 
> The actual interpretation is up to the console. Newportcon and sticon
> only handle blank or not-blank. Fbcon and vgacon implement blank plus
> the VESA DPMS handling. The implementation of both consoles is again
> somewhat confusing because types and values do not match. Clean up
> both with the new blank/blank_mode logic.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261012094114.38549-1-tzimmermann@suse.de?part=2