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    SubjectRe: [PATCH 05/15] tty: serial: Add 8250-core based omap driver
    On 08/15/2014 11:07 PM, Tony Lindgren wrote:
    > Nice, now it mostly works for me with off-idle too :) That is as long
    > as I have the DMA channels commented out in the .dts file.
    >
    > And I'm still seeing an occasional hang with pstore console just
    > showing:
    >
    > [ 289.076538] In-band Error seen by MPU at address 0
    > [ 289.076538] ------------[ cut here ]------------
    > [ 289.076568] WARNING: CPU: 0 PID: 99 at drivers/bus/omap_l3_smx.c:162 omap3_l3_app_irq+0xdc/0x134()
    > [ 289.076599] Modules linked in:
    > [ 289.076599] CPU: 0 PID: 99 Comm: test-idle-off-8 Tainted: G W 3.16.0+ #510
    > [ 289.076629] [<c0016c44>] (unwind_backtrace) from [<c00129c8>] (show_stack+0x20/0x24)
    > [ 289.076660] [<c00129c8>] (show_stack) from [<c0714cd4>] (dump_stack+0x88/0xa4)

    Okay. So this backtrace does not show more like from where the access
    is happening?

    > Which most likely means there's still some glitch with the
    > runtime PM somewhere and registers are being accessed when
    > not clocked. I _think_ I did not see it when I did not have
    > console=ttyS2,115200 in my cmdline but was using just pstore
    > console.
    >
    >> The device name is ttyS based instead of ttyO. If a ttyO based node name
    >> is required please ask udev for it. If both driver are activated (this
    >> and omap-serial) then this serial driver will take control over the
    >> device due to the link order
    >
    > That's still not going to help with the existing kernel cmdlines
    > and existing installs.. I wonder if we can just do a minimal
    > dummy serial-omap.c that just proxies all the ttyO read/write
    > access to ttyS?

    Hmm. So you are not a friend of the udev solution?. For now the driver
    is "default n" and you have to explicit enable it and _then_ you should
    be able to update your command line, etc.
    If I introduce a kernel proxy for compatibility I assume that people
    will wake up once that compatibility piece is gone.

    However, if you insist… I tried to make a symlink but nobody does this
    in kernel. The "rtc -> rtc0" and friends seem to come from udev _or_
    distro. So I sff could a second device node with the same major/minor.
    That would work for userland but not for the kernel console… So we need
    a proxy-console for this.

    Before I spent time on this proxy-console I would like to hear from Greg
    that he is okay with this.

    >
    > Regards,
    >
    > Tony

    Sebastian
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