[Skiboot] [PATCH] lpc: Clear sync no-response field prior to device probe

[Andrew Jeffery]

On Thu, 25 Oct 2018, at 15:04, Joel Stanley wrote:
> On Thu, 18 Oct 2018 at 18:29, Andrew Jeffery <andrew at aj.id.au> wrote:
> >
> > Artem Senichev reported[1] his P8 platform was failing to boot from
> > a43e9a66aae9 ("astbmc: Fail SFC init if SIO is unavailable") with the
> > following error:
> >
> > [  110.097168975,3] PLAT: Failed to open PNOR flash controller
> 
> Yep, this bricked my Garrison:

Agh. Sorry.

> 
> [  118.463273159,3] PLAT: Failed to open PNOR flash controller
> [  119.309908447,2] NVRAM: Failed to load
> [  119.309999680,2] NVRAM: Failed to load
> [  119.311393404,2] NVRAM: Failed to load
> [  119.312534959,2] NVRAM: Failed to load
> [  119.312612048,2] NVRAM: Failed to load
> 
> With your patch it looked okay. I did see this on the next boot:
> 
> [  138.038277373,7] OPAL: Start CPU 0x00ee (PIR 0x00ee) -> 0x000000000000a96c
> [  138.047297723,7] OPAL: Start CPU 0x00ef (PIR 0x00ef) -> 0x000000000000a96c
> [  138.097362833,3] LPC[000]: Got SYNC no-response error. Error
> address reg: 0xd001002f
> [  138.097391393,6] IPMI: dropping non severe PEL event

Hmm, yeah that's curious. I must admit I didn't get all the way to the bottom of the problem, the patch I sent fixes a correctness issue with the test which happens to have the side-effect of allowing the machine to boot. However, I don't know why the LPCHC is in this error state to begin with. I should look into that at some point.

> [  138.100886198,7] UART: IRQ functional !
> [  138.100939322,7] PHB#0009: Got interrupt 0x000057ff
> [  138.112595579,7] IPMI Get Message Flags: 02
> [  138.112995295,7] IPMI Get Message Flags: 02
> [  138.113537667,7] IPMI read event 35 complete: 16 bytes. cc: 00
> [  138.113542495,6] IPMI: dropping System Event Record SEL
> [  138.113998903,7] IPMI: Got error response 0x80
> 
> >
> > I reproduced this behaviour on a Palmetto; we need to ensure the state
> > of the no-response error bit is clear before proceding with the presence
> > test.
> >
> > The fix appears to resolve the failure to open the PNOR flash controller
> > on Palmetto and doesn't change the expected behaviour on Witherspoon.
> >
> > [1] https://github.com/open-power/skiboot/issues/197
> >
> > Signed-off-by: Andrew Jeffery <andrew at aj.id.au>
> 
> Tested-by: Joel Stanley <joel at jms.id.au>

Cheers

Andrew