[U-Boot] PPC 405EX hangs waiting for PCIE to reset

[U-Boot] PPC 405EX hangs waiting for PCIE to reset

[David Thomas]

We have a board with an AMCC PPC 405EX connected to two fpga's with PCIE 
interfaces.

On some boards, on power up, the u-boot code hangs in the while loop in 
the following code waiting for PCIE1 to come out of reset. PCIE0  comes 
out of reset successfully.

The PHYSTA for PCIE1 always reads back with the value 0x30000000, 
indicating the the interface is in the P2 state and that the PLL has not 
locked.

If a timeout is added and U-boot is allowed to proceed, a machine check 
is eventually taken and the processor reboots. During the reboot, u-boot 
runs through the same code but this time both PCIE interfaces 
successfully come out of reset and the board comes up normally.

Any suggestions about what might be happening here?

Thanks

David Thomas.



u-boot/arch/powerpc/cpu/ppc4xx/4xx_pcie.c, lines 840-848:

         SDR_WRITE(SDRN_PESDR_RCSSET(port), 0x01101000);

     /* poll for phy !reset */
     while (!(SDR_READ(SDRN_PESDR_PHYSTA(port)) & 0x00001000))
         ;

     /* deassert the PE0_gpl_utl_reset */
     SDR_WRITE(SDRN_PESDR_RCSSET(port), 0x00101000);

[U-Boot] PPC 405EX hangs waiting for PCIE to reset

[Stefan Roese]

Hi David,

On Friday 28 January 2011 14:57:06 David Thomas wrote:
> We have a board with an AMCC PPC 405EX connected to two fpga's with PCIE
> interfaces.
> 
> On some boards, on power up, the u-boot code hangs in the while loop in
> the following code waiting for PCIE1 to come out of reset. PCIE0  comes
> out of reset successfully.
> 
> The PHYSTA for PCIE1 always reads back with the value 0x30000000,
> indicating the the interface is in the P2 state and that the PLL has not
> locked.
> 
> If a timeout is added and U-boot is allowed to proceed, a machine check
> is eventually taken and the processor reboots. During the reboot, u-boot
> runs through the same code but this time both PCIE interfaces
> successfully come out of reset and the board comes up normally.
> 
> Any suggestions about what might be happening here?

Did you try setting the "pcidelay" environment variable. This will delay 
initializing the PCI(e) interfaces for n milliseconds. Try setting it to 3000 
(3 seconds) to see if this helps. Please note that you need to set 
CONFIG_PCI_BOOTDELAY in your board config header to enable this "feature".
 
Cheers,
Stefan

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