[Bug 10616] New: Impossible to change sync and vmode with fbset

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=10616

            Bug ID: 10616
           Summary: Impossible to change sync and vmode with fbset
           Product: Busybox
           Version: 1.24.x
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: Other
          Assignee: unassigned at busybox.net
          Reporter: frederic.jary at innes.fr
                CC: busybox-cvs at busybox.net
  Target Milestone: ---

Use case:
*********
Busybox is running on an embedded platform that does not take care of EDID
information. Therefore, the FBIOPUT_VSCREENINFO ioctl shall carry all the
needed parameters so that the underlying driver can properly set the graphical
mode. fb.modes is parsed externally to set the input parameters of fbset;
read_mode_db() is not used.

Call exemple:
fbset -fb /dev/fb0 -g 1920 1080 1920 1080 24 -t 6734 220 44 36 4 16 5 -hsync
low -vsync high -laced false

Issue 1:
********
sync and vmode in var_set are initialized to 0xFFFFFFFF (-1 if cast into
signed). Each one must be strictly positive to be taken into account (see
copy_if_gt0).
Therefore, a sync or a vmode equal to 0 is not reported in the ioctl.

Issue 2:
********
The logical OR on the following lines have no effect and behave in the same way
if the parameter is "high" or "low":
                        case CMD_HSYNC:
                                var_set.sync |= FB_SYNC_HOR_HIGH_ACT;
                                break;
                        case CMD_VSYNC:
                                var_set.sync |= FB_SYNC_VERT_HIGH_ACT;
                                break;

Issue 3:
********
The CMD_LACED is defined but not used.

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