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

Varadarajan Narayanan
2024-06-28T08:48:24Z

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.

Thanks
Varada