Re: [PATCH v9 6/6] arm64: dts: qcom: ipq9574: Add icc provider ability to gcc

Konrad Dybcio
2024-06-29T13:25:55Z

On 28.06.2024 10:48 AM, Varadarajan Narayanan wrote:
> On Thu, Jun 27, 2024 at 12:00:35AM +0200, Konrad Dybcio wrote:
>> On 19.06.2024 9:36 AM, Varadarajan Narayanan wrote:
>>
>> [...]
>>
>>
>>> Tested the patches with both gcc and nsscc providers having
>>> 'sync_state' set to icc_sync_state.
>>>
>>> # dmesg | grep synced
>>> [ 3.029820] qcom,gcc-ipq9574 1800000.clock-controller: interconnect provider is in synced state
>>> [ 3.470106] qcom,nsscc-ipq9574 39b00000.clock-controller: interconnect provider is in synced state
>>>
>>> I can see that icc_sync_state is getting called and clocks
>>> related to paths with zero bandwidth are getting disabled.
>>>
>>> Will post the NSSCC patches to get the full picture.
>>
>> Going back to the original question, does removing interconnects = from
>> things like PCIe now make them not work / crash the device, which would
>> indicate the NoC clocks were indeed gated?
>
> Yes. With and without 'interconnects =', the following behaviour
> is same
> * Boot completes
> * PCIe devices were probed succesfully and can be
> seen in /proc/bus/pci/devices.
> * icc_sync_state is called. The system has 4 pcie nodes
> in the DT, out of which pcie0 is not enabled.
>
> The difference is seen in icc_sync_state
>
> With 'interconnects ='
>
> * During icc_sync_state, the following 2 clocks
> corresponding to the interconnects of 'pcie0' get
> disabled.
>
> [ 2.986356] ---> clk_core_disable_lock: gcc_anoc_pcie0_1lane_m_clk
> [ 3.012486] ---> clk_core_disable_lock: gcc_snoc_pcie0_1lane_s_clk
>
> * System shutdown also completes without issues
>
> Without the 'interconnects =',
>
> * During icc_sync_state, the following clocks
> corresponding to the interconnects of all the 4 PCIe
> nodes get disabled.
>
> [ 2.887860] ---> clk_core_disable_lock: gcc_anoc_pcie0_1lane_m_clk
> [ 2.913988] ---> clk_core_disable_lock: gcc_snoc_pcie0_1lane_s_clk
> [ 2.939857] ---> clk_core_disable_lock: gcc_anoc_pcie1_1lane_m_clk
> [ 2.965725] ---> clk_core_disable_lock: gcc_snoc_pcie1_1lane_s_clk
> [ 2.991594] ---> clk_core_disable_lock: gcc_anoc_pcie2_2lane_m_clk
> [ 3.017463] ---> clk_core_disable_lock: gcc_snoc_pcie2_2lane_s_clk
> [ 3.043328] ---> clk_core_disable_lock: gcc_anoc_pcie3_2lane_m_clk
> [ 3.069201] ---> clk_core_disable_lock: gcc_snoc_pcie3_2lane_s_clk
>
> * System shutdown hangs (possibly due to un-clocked
> access of PCIe register) in pcie_pme_interrupt_enable
>
> [ 10.773134] dump_stack+0x18/0x24
> [ 10.776779] pcie_pme_remove+0x2c/0x88
> [ 10.780078] pcie_port_remove_service+0x50/0x74
> [ 10.783725] device_remove+0x12c/0x148
> [ 10.788151] __device_release_driver+0x65c/0x8cc
> [ 10.791972] device_release_driver+0x2c/0x44
> [ 10.796746] bus_remove_device+0xcc/0x10c
> [ 10.800999] device_del+0x14c/0x400
> [ 10.804904] device_unregister+0x18/0x34
> [ 10.808203] remove_iter+0x2c/0x3c
> [ 10.812369] device_for_each_child+0x60/0xb4
> [ 10.815583] pcie_portdrv_shutdown+0x34/0x90
> [ 10.820009] pci_device_shutdown+0x34/0x74
> [ 10.824263] device_shutdown+0x150/0x258
> [ 10.828169] kernel_restart_prepare+0x98/0xbc
> [ 10.832249] kernel_restart+0x44/0x110
> [ 10.836502] __do_sys_reboot+0x18c/0x304
>
> I believe, this is confirms NOC clocks getting disabled by
> icc_sync_state.

Yes, this looks good now, thanks.

Konrad