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    SubjectRe: PM/FB/gxfb: add config option that allows disabling of VT switch during suspend
    On 10/03/08 18:14 -0400, Andres Salomon wrote:
    > On Mon, 10 Mar 2008 14:51:18 -0700
    > Andrew Morton <akpm@linux-foundation.org> wrote:
    >
    > > On Mon, 10 Mar 2008 17:44:24 -0400
    > > Andres Salomon <dilinger@queued.net> wrote:
    > >
    > > > On Mon, 10 Mar 2008 14:19:39 -0700
    > > > Andrew Morton <akpm@linux-foundation.org> wrote:
    > > >
    > > > >
    > > > > It would be far preferable to do this via a kernel boot parameter rather
    > > > > than via a kernel rebuild.
    > > > >
    > > >
    > > > Well, it shouldn't be supported at _all_ unless the framebuffer driver
    > > > supports it; you're asking for it to be converted to something like the
    > > > following?
    > > >
    > > >
    > > >
    > > > #ifdef CONFIG_FBDEV_SUPPORTS_NOSWITCH
    > > > static int no_vt_switch;
    > > > #endif
    > > >
    > > > int pm_prepare_console(void)
    > > > {
    > > > #ifdef CONFIG_FBDEV_SUPPORTS_NOSWITCH
    > > > if (no_vt_switch)
    > > > return 0;
    > > > #endif
    > > > ...
    > > > }
    > > >
    > > > #ifdef CONFIG_FBDEV_SUPPORTS_NOSWITCH
    > > > module_param(no_vt_switch, int, 0);
    > > > MODULE_PARM_DESC(no_vt_switch, "...");
    > > > #endif
    > > >
    > > >
    > > > If so, that means extra #ifdef's sprinkled throughout the code. Note
    > > > that most framebuffer drivers won't be supporting this, and those that
    > > > do will almost certainly always want vt switching turned off..
    > > >
    > >
    > > I don't think you need any ifdefs or config options at all, do you? Just
    > > add a new module parameter to this driver and some little interface into
    > > the PM core which allows the driver to set no_vt_switch?
    > >
    >
    > That's a possibility, but doesn't adding hooks into PM core for two
    > drivers (lxfb and gxfb) seems like overkill? I also don't really see
    > anyone needing to switch back and forth between VT_SWITCH and
    > NO_VT_SWITCH other than to work around possible bugs in the register
    > save/restore code..

    I like Andrew's idea. I wager This won't be Geode specific for long.
    Either other drivers will get the hint and add real save/restore code
    or the GPU subystem code being worked on by the X folks will come along
    and make the VT switch obsolete for everybody. Either way, I see hooks
    in the PM core as generic love that everybody can benefit from.

    Jordan

    --
    Jordan Crouse
    Systems Software Development Engineer
    Advanced Micro Devices, Inc.



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