[U-Boot] What's purpose of DEV_FLAGS_SYSTEM and DEV_EXT_VIDEO?

[Bin Meng]

On Mon, Aug 17, 2015 at 1:09 PM, Bin Meng <bmeng.cn at gmail.com> wrote:
> Hi,
>
> I plan to send a patch to remove the DEV_FLAGS_SYSTEM and
> DEV_EXT_VIDEO. They look useless to me. For example,
>
> $ grep -nr DEV_FLAGS_SYSTEM *
> arch/blackfin/cpu/jtag-console.c:186:   dev.flags = DEV_FLAGS_OUTPUT |
> DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
> board/bf527-ezkit/video.c:442:  videodev.flags = DEV_FLAGS_SYSTEM;
>  /* No Output */
> board/kosagi/novena/novena.c:80:                .flags  =
> DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM,
> board/cm-bf548/video.c:336:     videodev.flags = DEV_FLAGS_SYSTEM;
>  /* No Output */
> board/mpl/common/kbd.c:206:     kbddev.flags =  DEV_FLAGS_INPUT |
> DEV_FLAGS_SYSTEM;
> board/mpl/pati/pati.c:569:      pci_con_dev.flags = DEV_FLAGS_OUTPUT |
> DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
> board/bf548-ezkit/video.c:332:  videodev.flags = DEV_FLAGS_SYSTEM;
>  /* No Output */
> board/bf533-stamp/video.c:168:  videodev.flags = DEV_FLAGS_SYSTEM;
> common/cmd_console.c:33:                        (dev->flags &
> DEV_FLAGS_SYSTEM) ? 'S' : '.',
> common/usb_kbd.c:505:   usb_kbd_dev.flags =  DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
> common/stdio.c:91:      dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT
> | DEV_FLAGS_SYSTEM;
> common/stdio.c:102:     dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT
> | DEV_FLAGS_SYSTEM;
> drivers/input/cros_ec_keyb.c:261:       dev.flags = DEV_FLAGS_INPUT |
> DEV_FLAGS_SYSTEM;
> drivers/input/tegra-kbc.c:361:  dev.flags = DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
> drivers/input/keyboard.c:277:   kbddev.flags =  DEV_FLAGS_INPUT |
> DEV_FLAGS_SYSTEM;
> drivers/video/cfb_console.c:2296:       console_dev.flags =
> DEV_FLAGS_OUTPUT | DEV_FLAGS_SYSTEM;
> drivers/net/netconsole.c:325:   dev.flags = DEV_FLAGS_OUTPUT |
> DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
> include/stdio_dev.h:19:#define DEV_FLAGS_SYSTEM 0x80000000      /*
> Device is a system device            */
>
> Except for this one below which tests the flag and prints an 'S',
> common/cmd_console.c:33:                        (dev->flags &
> DEV_FLAGS_SYSTEM) ? 'S' : '.',
>
> I don't see any actual meaning of this flag. I wonder if someone on
> the mailing list knows the history.
>
> Also I noticed that several blackfin boards' video driver only set
> this flag without setting DEV_FLAGS_OUTPUT.
>
> board/bf527-ezkit/video.c:442:  videodev.flags = DEV_FLAGS_SYSTEM;
>  /* No Output */
> board/cm-bf548/video.c:336:     videodev.flags = DEV_FLAGS_SYSTEM;
>  /* No Output */
> board/bf548-ezkit/video.c:332:  videodev.flags = DEV_FLAGS_SYSTEM;
>  /* No Output */
> board/bf533-stamp/video.c:168:  videodev.flags = DEV_FLAGS_SYSTEM;
>
> I wonder these video drivers are not used for system output purpose?
>

Ping?

Regards,
Bin