Re: [PATCH v6 05/13] PCI: brcmstb: Use bridge reset if available

[Stanimir Varbanov <svarbanov@suse.de>]

Hi Jim,

On 8/19/24 21:09, Jim Quinlan wrote:
> On Sat, Aug 17, 2024 at 1:41 PM Stanimir Varbanov <svarbanov@suse.de> wrote:
>>
>> Hi Jim,
>>
>> On 8/16/24 01:57, Jim Quinlan wrote:
>>> The 7712 SOC has a bridge reset which can be described in the device tree.
>>> Use it if present.  Otherwise, continue to use the legacy method to reset
>>> the bridge.
>>>
>>> Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
>>> ---
>>>  drivers/pci/controller/pcie-brcmstb.c | 24 +++++++++++++++++++-----
>>>  1 file changed, 19 insertions(+), 5 deletions(-)
>>
>> Reviewed-by: Stanimir Varbanov <svarbanov@suse.de>
>>
>> One problem though on RPi5 (bcm2712).
>>
>> With this series applied + my WIP patches for enablement of PCIe on
>> bcm2712 when enable the pcie1 and pcie2 root ports in dts, I see kernel
>> boot stuck on pcie2 enumeration and I have to add this [1] to make it
>> work again.
>>
>> Some more info about resets used:
>>
>> pcie0 @ 100000:
>>         resets = <&bcm_reset 5>, <&bcm_reset 42>, <&pcie_rescal>;
>>         reset-names = "swinit", "bridge", "rescal";
>>
>> pcie1 @ 110000:
>>         resets = <&bcm_reset 7>, <&bcm_reset 43>, <&pcie_rescal>;
>>         reset-names = "swinit", "bridge", "rescal";
>>
>> pcie2 @ 120000:
>>         resets = <&bcm_reset 9>, <&bcm_reset 44>, <&pcie_rescal>;
>>         reset-names = "swinit", "bridge", "rescal";
>>
>>
>> I changed "swinit" reset for pcie2 to <&bcm_reset 9> (it is 32 in
>> downstream rpi kernel) because otherwise I'm unable to enumerate RP1
>> south bridge at all.
>>
>> Any help will be appreciated.
> 
> Hi Stan,
> Let me look into this.  Why is one of the controllers turning off --
> is it not populated with a device?

Yes, I enabled pcie1 but no PCI endpoint devices attached on the
expansion connector.

> 
> As you probably know the 7712 only has access to PCIe1.  But we do
> have another chip with two controllers and I will try to reproduce
> your failure and get to the bottom of it.

Thank you for the help.

~Stan

> 
> Regards,
> Jim Quinlan
> Broadcom STB/CM
>>
>> ~Stan
>>
>> [1]
>> https://github.com/raspberrypi/linux/blob/rpi-6.11.y/drivers/pci/controller/pcie-brcmstb.c#L1711