serial: of-serial: fetch line number from DT

serial: of-serial: fetch line number from DT

[Olof Johansson]

Greg,

This commit:

commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
Author: Lucas Stach <dev@lynxeye.de>
Date:   Mon Nov 3 23:16:54 2014 +0100

    serial: of-serial: fetch line number from DT

    The general agreed way to specify a fixed line number
    for a serial console is to provide a "serial" alias
    in the devicetree. Start parsing this property in
    of_serial.

    Signed-off-by: Lucas Stach <dev@lynxeye.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


Broke a whole lot of tegra boards in last night's -next here. In
particular, I've been looking at tegra20-seaboard, which now doesn't
boot with console any more.

http://arm-soc.lixom.net/bootlogs/next/next-20141110/

Unfortunately, tegra has for a long time been specifying the aliases
as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
first _activated_ serial port. That's obviously going to break things
here. :(

Greg, can you please revert until we get the tegra-side fixes in for
this, or we're in for a pretty lousy time w.r.t. bisecting problems
across the two mergepoints?

Stephen: I suppose the best way to handle this on tegra is to specify
the aliases per-board instead of in the soc dtsi today.

Apologies for not replying to the patch directly -- it was only ever
posted to linux-serial and I don't seem to be subscribed.


-Olof

serial: of-serial: fetch line number from DT

[Stephen Warren]

On 11/10/2014 02:34 PM, Olof Johansson wrote:
> Greg,
>
> This commit:
>
> commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
> Author: Lucas Stach <dev@lynxeye.de>
> Date:   Mon Nov 3 23:16:54 2014 +0100
>
>      serial: of-serial: fetch line number from DT
...
> Broke a whole lot of tegra boards in last night's -next here. In
> particular, I've been looking at tegra20-seaboard, which now doesn't
> boot with console any more.
>
> http://arm-soc.lixom.net/bootlogs/next/next-20141110/
>
> Unfortunately, tegra has for a long time been specifying the aliases
> as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
> first _activated_ serial port. That's obviously going to break things
> here. :(
...
> Stephen: I suppose the best way to handle this on tegra is to specify
> the aliases per-board instead of in the soc dtsi today.

IIRC, there was a deliberate request to name the Tegra UARTs after the 
SoC ports rather than board ports, so that it'd be obvious to people 
which port was which. I'm not sure if we can change the aliases in the 
Tegra DTs now that people may have got used to them?

serial: of-serial: fetch line number from DT

[Olof Johansson]

On Mon, Nov 10, 2014 at 1:38 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
> On 11/10/2014 02:34 PM, Olof Johansson wrote:
>>
>> Greg,
>>
>> This commit:
>>
>> commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
>> Author: Lucas Stach <dev@lynxeye.de>
>> Date:   Mon Nov 3 23:16:54 2014 +0100
>>
>>      serial: of-serial: fetch line number from DT
>
> ...
>>
>> Broke a whole lot of tegra boards in last night's -next here. In
>> particular, I've been looking at tegra20-seaboard, which now doesn't
>> boot with console any more.
>>
>> http://arm-soc.lixom.net/bootlogs/next/next-20141110/
>>
>> Unfortunately, tegra has for a long time been specifying the aliases
>> as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
>> first _activated_ serial port. That's obviously going to break things
>> here. :(
>
> ...
>>
>> Stephen: I suppose the best way to handle this on tegra is to specify
>> the aliases per-board instead of in the soc dtsi today.
>
>
> IIRC, there was a deliberate request to name the Tegra UARTs after the SoC
> ports rather than board ports, so that it'd be obvious to people which port
> was which. I'm not sure if we can change the aliases in the Tegra DTs now
> that people may have got used to them?

I think that's a great idea in general, but they've been this way now
for 4 years and it'll mean everyone changing bootargs and console
configurations (where to spawn getty) everywhere. :(


-Olof

serial: of-serial: fetch line number from DT

[Greg Kroah-Hartman]

On Mon, Nov 10, 2014 at 01:34:19PM -0800, Olof Johansson wrote:
> Greg,
> 
> This commit:
> 
> commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
> Author: Lucas Stach <dev@lynxeye.de>
> Date:   Mon Nov 3 23:16:54 2014 +0100
> 
>     serial: of-serial: fetch line number from DT
> 
>     The general agreed way to specify a fixed line number
>     for a serial console is to provide a "serial" alias
>     in the devicetree. Start parsing this property in
>     of_serial.
> 
>     Signed-off-by: Lucas Stach <dev@lynxeye.de>
>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> 
> Broke a whole lot of tegra boards in last night's -next here. In
> particular, I've been looking at tegra20-seaboard, which now doesn't
> boot with console any more.
> 
> http://arm-soc.lixom.net/bootlogs/next/next-20141110/
> 
> Unfortunately, tegra has for a long time been specifying the aliases
> as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
> first _activated_ serial port. That's obviously going to break things
> here. :(
> 
> Greg, can you please revert until we get the tegra-side fixes in for
> this, or we're in for a pretty lousy time w.r.t. bisecting problems
> across the two mergepoints?
> 
> Stephen: I suppose the best way to handle this on tegra is to specify
> the aliases per-board instead of in the soc dtsi today.
> 
> Apologies for not replying to the patch directly -- it was only ever
> posted to linux-serial and I don't seem to be subscribed.

Now reverted, sorry for the problems.

greg k-h

serial: of-serial: fetch line number from DT

[Lucas Stach]

Am Montag, den 10.11.2014, 14:38 -0700 schrieb Stephen Warren:
> On 11/10/2014 02:34 PM, Olof Johansson wrote:
> > Greg,
> >
> > This commit:
> >
> > commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
> > Author: Lucas Stach <dev@lynxeye.de>
> > Date:   Mon Nov 3 23:16:54 2014 +0100
> >
> >      serial: of-serial: fetch line number from DT
> ...
> > Broke a whole lot of tegra boards in last night's -next here. In
> > particular, I've been looking at tegra20-seaboard, which now doesn't
> > boot with console any more.
> >
> > http://arm-soc.lixom.net/bootlogs/next/next-20141110/
> >
> > Unfortunately, tegra has for a long time been specifying the aliases
> > as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
> > first _activated_ serial port. That's obviously going to break things
> > here. :(
> ...
> > Stephen: I suppose the best way to handle this on tegra is to specify
> > the aliases per-board instead of in the soc dtsi today.
> 
> IIRC, there was a deliberate request to name the Tegra UARTs after the 
> SoC ports rather than board ports, so that it'd be obvious to people 
> which port was which. I'm not sure if we can change the aliases in the 
> Tegra DTs now that people may have got used to them?
> 
First off: sorry for breaking stuff.

The point of this patch was exactly to have a common naming scheme
between bootloader and and kernel. The aliases provide this in a broadly
recognized way.
Relying on the fact that ttyS0 maps to the debug UART seems extremely
fragile and the fact that this patch broke this assumption actually
proves this.

IMHO it is a bug in U-Boot that it doesn't look at the aliases when it
builds the console= kernel parameter. But I recognize the problem that
this change introduces a non-backward compatible break between firmware
and kernel and I don't yet see a nice solution for this.

Regards,
Lucas

-- 
Pengutronix e.K.             | Lucas Stach                 |
Industrial Linux Solutions   | http://www.pengutronix.de/  |

serial: of-serial: fetch line number from DT

[Olof Johansson]

On Mon, Nov 10, 2014 at 9:24 PM, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> On Mon, Nov 10, 2014 at 01:34:19PM -0800, Olof Johansson wrote:
>> Greg,
>>
>> This commit:
>>
>> commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
>> Author: Lucas Stach <dev@lynxeye.de>
>> Date:   Mon Nov 3 23:16:54 2014 +0100
>>
>>     serial: of-serial: fetch line number from DT
>>
>>     The general agreed way to specify a fixed line number
>>     for a serial console is to provide a "serial" alias
>>     in the devicetree. Start parsing this property in
>>     of_serial.
>>
>>     Signed-off-by: Lucas Stach <dev@lynxeye.de>
>>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>
>>
>> Broke a whole lot of tegra boards in last night's -next here. In
>> particular, I've been looking at tegra20-seaboard, which now doesn't
>> boot with console any more.
>>
>> http://arm-soc.lixom.net/bootlogs/next/next-20141110/
>>
>> Unfortunately, tegra has for a long time been specifying the aliases
>> as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
>> first _activated_ serial port. That's obviously going to break things
>> here. :(
>>
>> Greg, can you please revert until we get the tegra-side fixes in for
>> this, or we're in for a pretty lousy time w.r.t. bisecting problems
>> across the two mergepoints?
>>
>> Stephen: I suppose the best way to handle this on tegra is to specify
>> the aliases per-board instead of in the soc dtsi today.
>>
>> Apologies for not replying to the patch directly -- it was only ever
>> posted to linux-serial and I don't seem to be subscribed.
>
> Now reverted, sorry for the problems.

No worries, it's what linux-next is for. Thanks for the revert!


-Olof

serial: of-serial: fetch line number from DT

[Lucas Stach]

Hi Greg,

Am Dienstag, den 11.11.2014, 08:51 -0800 schrieb Olof Johansson:
> On Mon, Nov 10, 2014 at 9:24 PM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > On Mon, Nov 10, 2014 at 01:34:19PM -0800, Olof Johansson wrote:
> >> Greg,
> >>
> >> This commit:
> >>
> >> commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
> >> Author: Lucas Stach <dev@lynxeye.de>
> >> Date:   Mon Nov 3 23:16:54 2014 +0100
> >>
> >>     serial: of-serial: fetch line number from DT
> >>
> >>     The general agreed way to specify a fixed line number
> >>     for a serial console is to provide a "serial" alias
> >>     in the devicetree. Start parsing this property in
> >>     of_serial.
> >>
> >>     Signed-off-by: Lucas Stach <dev@lynxeye.de>
> >>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >>
> >>
> >> Broke a whole lot of tegra boards in last night's -next here. In
> >> particular, I've been looking at tegra20-seaboard, which now doesn't
> >> boot with console any more.
> >>
> >> http://arm-soc.lixom.net/bootlogs/next/next-20141110/
> >>
> >> Unfortunately, tegra has for a long time been specifying the aliases
> >> as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
> >> first _activated_ serial port. That's obviously going to break things
> >> here. :(
> >>
> >> Greg, can you please revert until we get the tegra-side fixes in for
> >> this, or we're in for a pretty lousy time w.r.t. bisecting problems
> >> across the two mergepoints?
> >>
> >> Stephen: I suppose the best way to handle this on tegra is to specify
> >> the aliases per-board instead of in the soc dtsi today.
> >>
> >> Apologies for not replying to the patch directly -- it was only ever
> >> posted to linux-serial and I don't seem to be subscribed.
> >
> > Now reverted, sorry for the problems.
> 
> No worries, it's what linux-next is for. Thanks for the revert!
> 
As 3.18-rc6 now landed the fix to avoid the regression on Tegra would
you please consider reapplying this patch?

Regards,
Lucas

serial: of-serial: fetch line number from DT

[Greg Kroah-Hartman]

On Mon, Nov 24, 2014 at 10:41:39PM +0100, Lucas Stach wrote:
> Hi Greg,
> 
> Am Dienstag, den 11.11.2014, 08:51 -0800 schrieb Olof Johansson:
> > On Mon, Nov 10, 2014 at 9:24 PM, Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > > On Mon, Nov 10, 2014 at 01:34:19PM -0800, Olof Johansson wrote:
> > >> Greg,
> > >>
> > >> This commit:
> > >>
> > >> commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
> > >> Author: Lucas Stach <dev@lynxeye.de>
> > >> Date:   Mon Nov 3 23:16:54 2014 +0100
> > >>
> > >>     serial: of-serial: fetch line number from DT
> > >>
> > >>     The general agreed way to specify a fixed line number
> > >>     for a serial console is to provide a "serial" alias
> > >>     in the devicetree. Start parsing this property in
> > >>     of_serial.
> > >>
> > >>     Signed-off-by: Lucas Stach <dev@lynxeye.de>
> > >>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > >>
> > >>
> > >> Broke a whole lot of tegra boards in last night's -next here. In
> > >> particular, I've been looking at tegra20-seaboard, which now doesn't
> > >> boot with console any more.
> > >>
> > >> http://arm-soc.lixom.net/bootlogs/next/next-20141110/
> > >>
> > >> Unfortunately, tegra has for a long time been specifying the aliases
> > >> as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
> > >> first _activated_ serial port. That's obviously going to break things
> > >> here. :(
> > >>
> > >> Greg, can you please revert until we get the tegra-side fixes in for
> > >> this, or we're in for a pretty lousy time w.r.t. bisecting problems
> > >> across the two mergepoints?
> > >>
> > >> Stephen: I suppose the best way to handle this on tegra is to specify
> > >> the aliases per-board instead of in the soc dtsi today.
> > >>
> > >> Apologies for not replying to the patch directly -- it was only ever
> > >> posted to linux-serial and I don't seem to be subscribed.
> > >
> > > Now reverted, sorry for the problems.
> > 
> > No worries, it's what linux-next is for. Thanks for the revert!
> > 
> As 3.18-rc6 now landed the fix to avoid the regression on Tegra would
> you please consider reapplying this patch?

What patch?  Please resend it, AND, get everyone to agree that it's not
going to break anything.

greg k-h

serial: of-serial: fetch line number from DT

[Olof Johansson]

On Mon, Nov 24, 2014 at 1:57 PM, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> On Mon, Nov 24, 2014 at 10:41:39PM +0100, Lucas Stach wrote:
>> Hi Greg,
>>
>> Am Dienstag, den 11.11.2014, 08:51 -0800 schrieb Olof Johansson:
>> > On Mon, Nov 10, 2014 at 9:24 PM, Greg Kroah-Hartman
>> > <gregkh@linuxfoundation.org> wrote:
>> > > On Mon, Nov 10, 2014 at 01:34:19PM -0800, Olof Johansson wrote:
>> > >> Greg,
>> > >>
>> > >> This commit:
>> > >>
>> > >> commit 1bd8324535ec1ff44aef55c0e40b9e7d56b310fb
>> > >> Author: Lucas Stach <dev@lynxeye.de>
>> > >> Date:   Mon Nov 3 23:16:54 2014 +0100
>> > >>
>> > >>     serial: of-serial: fetch line number from DT
>> > >>
>> > >>     The general agreed way to specify a fixed line number
>> > >>     for a serial console is to provide a "serial" alias
>> > >>     in the devicetree. Start parsing this property in
>> > >>     of_serial.
>> > >>
>> > >>     Signed-off-by: Lucas Stach <dev@lynxeye.de>
>> > >>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> > >>
>> > >>
>> > >> Broke a whole lot of tegra boards in last night's -next here. In
>> > >> particular, I've been looking at tegra20-seaboard, which now doesn't
>> > >> boot with console any more.
>> > >>
>> > >> http://arm-soc.lixom.net/bootlogs/next/next-20141110/
>> > >>
>> > >> Unfortunately, tegra has for a long time been specifying the aliases
>> > >> as a fixed 1:1 mapping, but most environments rely on ttyS0 being the
>> > >> first _activated_ serial port. That's obviously going to break things
>> > >> here. :(
>> > >>
>> > >> Greg, can you please revert until we get the tegra-side fixes in for
>> > >> this, or we're in for a pretty lousy time w.r.t. bisecting problems
>> > >> across the two mergepoints?
>> > >>
>> > >> Stephen: I suppose the best way to handle this on tegra is to specify
>> > >> the aliases per-board instead of in the soc dtsi today.
>> > >>
>> > >> Apologies for not replying to the patch directly -- it was only ever
>> > >> posted to linux-serial and I don't seem to be subscribed.
>> > >
>> > > Now reverted, sorry for the problems.
>> >
>> > No worries, it's what linux-next is for. Thanks for the revert!
>> >
>> As 3.18-rc6 now landed the fix to avoid the regression on Tegra would
>> you please consider reapplying this patch?
>
> What patch?  Please resend it, AND, get everyone to agree that it's not
> going to break anything.

I'm OK with it going in now, since as mentioned above the tegra DTS
changes that resolved the issue have gone in as of -rc6.

Lucas, feel free to add my ack when you resend your patch.


-Olof