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

[Tom Rini]

On Wed, Sep 02, 2015 at 08:05:47AM -0600, Simon Glass wrote:
> Hi,
> 
> On 2 September 2015 at 03:44, Bin Meng <bmeng.cn at gmail.com> wrote:
> > 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?
> 
> This is from the dawn of time and I don't see any purpose still remaining.

Sounds reasonable.

-- 
Tom
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