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    SubjectRe: s2ram slow resume - radeon versus no_console_suspend?
    On Sun, 02 May 2010 Bruno Prémont <bonbons@linux-vserver.org> wrote:
    > On a IEI Kino 690S1 I'm having a hard time to get s2ram running.
    >
    > When the system is able to suspend it takes an eternity (more than 3
    > minutes to wake-up, the radeon apparently being responsible for quite
    > a big share of that slowness.
    >
    >
    > During resume early it looks like every PCI access needs about a second,
    > and there are a few cases where during lots of seconds nothing seems to
    > happen and the first event following is related to radeon.

    This slowness only happens when I run the kernel with no_console_suspend
    parameter (e.g. to debug some suspend/resume issue).
    This probably means that in this case radeon's PCI config recorded during
    suspend and restored during early resume is all but appropriate...

    Currently drm/radeon does not suspend when no_console_suspend is provided,
    even so when the kernel logging does not happen on tty0 & co.

    e.g. I would expect that a kernel run with
    no_console_suspend console=ttyS0
    would just skip suspending serial port ttyS0 and not also skip suspending
    KMS framebuffer as it currently does.


    In most framebuffer devices I see usage of acquire_console_sem() and
    release_console_sem() but except for kernel/printk.c and drivers/serial/
    code nothing is considering console_suspend_enabled.

    Currently I'm not sure what code path prevents suspend of KMS (at least
    for radeon) when no_console_suspend has been passed, this code path should
    probably have a conditional just as serial to take no_console_suspend only
    if it's running kernel's console itself.

    Thanks,
    Bruno
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