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

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Date: Sat, 29 Jun 2024 15:25:51 +0200
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Varadarajan Narayanan <quic_varada@...cinc.com>
Cc: Georgi Djakov <djakov@...nel.org>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, andersson@...nel.org,
 mturquette@...libre.com, sboyd@...nel.org, robh@...nel.org,
 krzk+dt@...nel.org, conor+dt@...nel.org, quic_anusha@...cinc.com,
 linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org
Subject: Re: [PATCH v9 6/6] arm64: dts: qcom: ipq9574: Add icc provider
 ability to gcc

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