Re: [RFC] clk: meson: t7: Intermittent boot instability and memory corruption on VIM4

[Lucas Tanure <tanure@linux.com>]

On 26/08/2026 10:55, Lucas Tanure wrote:
> On 24/08/2026 16:29, Brian Masney wrote:
>> Hi Lucas,
>>
>> On Sun, Aug 23, 2026 at 04:40:42PM +0100, Lucas Tanure wrote:
>>> While testing mainline Linux on the Khadas VIM4 (Amlogic A311D2 / 
>>> T7), I am
>>> hitting intermittent system instability, storage loss, and memory 
>>> corruption
>>> during boot, unless I append clk_ignore_unused to the kernel command 
>>> line.
>>>
>>> Because the failure is intermittent, I am running 100-reboot test 
>>> campaigns
>>> to bisect the remaining clocks and isolate which clocks are critical and
>>> cannot be safely disabled.
>>>
>>> As testing takes significant time over serial console, I wanted to 
>>> check if
>>> Amlogic or the maintainers could shed light on this:
>>>
>>> Are there specific T7 clocks or hardware domains that must remain
>>> critical/protected even without an explicit in-kernel consumer?
>>>
>>> Current clocks being disabled that don't kill the board on a test run:
>>>
>>> [    0.380313] clk: Disabling unused clocks
>>> [    0.380413] clk: Disabled unused clock: rtc_dualdiv
>>> [    0.380718] clk: Disabled unused clock: rtc_duandiv_in
>>> [    0.381377] clk: Unprepared unused clock: a73_div16
>>> [    0.381972] clk: Unprepared unused clock: cpu_div16
>>> [    0.382605] clk: Unprepared unused clock: f50m
>>> [    0.383174] clk: Unprepared unused clock: fixed_pll_dco
>>> [    0.383786] clk: Unprepared unused clock: hdmi_pll_osc
>>> [    0.384416] clk: Unprepared unused clock: sys1_pll_osc
>>> [    0.385056] clk: Unprepared unused clock: earc_osc
>>> [    0.385652] clk: Unprepared unused clock: pcie_refclk_osc
>>> [    0.386323] clk: Unprepared unused clock: eth_pll_osc
>>> [    0.386961] clk: Unprepared unused clock: pcie_osc
>>> [    0.387548] clk: Unprepared unused clock: mclk_pll_osc
>>> [    0.388187] clk: Unprepared unused clock: usb_pll1_osc
>>> [    0.388826] clk: Unprepared unused clock: usb_pll0_osc
>>> [    0.389465] clk: Unprepared unused clock: tcon_pll_osc
>>> [    0.390105] clk: Unprepared unused clock: top_pll_osc
>>> [    0.390738] clk: Unprepared unused clock: aud_pll_osc
>>> [    0.391361] clk: Unprepared unused clock: ddr_pll_osc
>>>
>>> I am not forcing any clock to be disabled; I am forcing all clocks to 
>>> stay
>>> on and letting them be disabled if unused one by one.
>>>
>>> Any guidance or hints on required platform clocks would be greatly
>>> appreciated.
>>
>> I have an outstanding series that disables unused clocks via the
>> sync_state callback:
>>
>> https://lore.kernel.org/linux-clk/20260626-clk-sync-state- 
>> v1-0-4156d8196dc8@redhat.com/
>>
>> Be sure to not have clk_ignore_unused in your kernel command line.
>>
>> I suggest comparing the list of which clocks are disabled with that
>> series against your list of clocks above.
> Thanks for the input, it did not solve the issue. I am going to produce 
> the list with a diff in disabled clocks with and without our change, but
> it did not solve the issue.
>>
>> Brian
>>
> 
With Brian's patches, VIM4 does not turn off 4 clocks:

t7_sys_sd_emmc_b
t7_sys_sd_emmc_c
sd_emmc_b
sd_emmc_c

This is expected since I'm trying to run from an SD card. However, even 
with these four clocks kept enabled, the board still hangs.

Complete list with all clocks being disabled after Brians patches:
[    1.002247] clk: Disabled unused clock: t7_sys_pwm_ao_gh
[    1.002898] clk: Disabled unused clock: t7_sys_pwm_ao_ef
[    1.003560] clk: Disabled unused clock: t7_sys_pwm_ao_cd
[    1.004220] clk: Disabled unused clock: t7_sys_pwm_ao_ab
[    1.004972] clk: Disabled unused clock: t7_sys_pwm_ef
[    1.005509] clk: Disabled unused clock: t7_sys_pwm_cd
[    1.006211] clk: Disabled unused clock: t7_sys_pwm_ab
[    1.006766] clk: Disabled unused clock: t7_sys_ts_hevc
[    1.007434] clk: Disabled unused clock: t7_sys_ts_vpu
[    1.008033] clk: Disabled unused clock: t7_sys_ts_nna
[    1.008741] clk: Disabled unused clock: t7_sys_ts_gpu
[    1.009294] clk: Disabled unused clock: t7_sys_sar_adc
[    1.009929] clk: Disabled unused clock: t7_sys_vpu_intr
[    1.010609] clk: Disabled unused clock: t7_sys_dspb
[    1.011186] clk: Disabled unused clock: t7_sys_dspa
[    1.011792] clk: Disabled unused clock: t7_sys_a73pclk_apb
[    1.012554] clk: Disabled unused clock: t7_sys_pclk_sys_apb
[    1.013213] clk: Disabled unused clock: t7_sys_rsa
[    1.013811] clk: Disabled unused clock: t7_sys_mipi_isp_pclk
[    1.014529] clk: Disabled unused clock: t7_sys_mmc_apb
[    1.015107] clk: Disabled unused clock: t7_sys_hdmirx_pclk
[    1.015819] clk: Disabled unused clock: t7_sys_i2c_s_a
[    1.016429] clk: Disabled unused clock: t7_sys_hdmitx_apb
[    1.017109] clk: Disabled unused clock: t7_sys_i2c_m_f
[    1.017740] clk: Disabled unused clock: t7_sys_i2c_m_e
[    1.018379] clk: Disabled unused clock: t7_sys_i2c_m_d
[    1.019018] clk: Disabled unused clock: t7_sys_i2c_m_c
[    1.019657] clk: Disabled unused clock: t7_sys_i2c_m_b
[    1.020296] clk: Disabled unused clock: t7_sys_i2c_m_a
[    1.020940] clk: Disabled unused clock: t7_sys_i2c_ao_b
[    1.021585] clk: Disabled unused clock: t7_sys_i2c_ao_a
[    1.022236] clk: Disabled unused clock: t7_sys_pcie_phy
[    1.022885] clk: Disabled unused clock: t7_sys_usb
[    1.023482] clk: Disabled unused clock: t7_sys_pcie
[    1.024088] clk: Disabled unused clock: t7_sys_spicc1
[    1.024723] clk: Disabled unused clock: t7_sys_spicc0
[    1.025345] clk: Disabled unused clock: t7_sys_g2d
[    1.025940] clk: Disabled unused clock: t7_sys_spicc5
[    1.026569] clk: Disabled unused clock: t7_sys_ts_a53
[    1.027197] clk: Disabled unused clock: t7_sys_ts_a73
[    1.027825] clk: Disabled unused clock: t7_sys_spicc4
[    1.028454] clk: Disabled unused clock: t7_sys_spicc3
[    1.029085] clk: Disabled unused clock: t7_sys_spicc2
[    1.029710] clk: Disabled unused clock: t7_sys_aififo
[    1.030339] clk: Disabled unused clock: t7_sys_uart_f
[    1.030967] clk: Disabled unused clock: t7_sys_uart_e
[    1.031595] clk: Disabled unused clock: t7_sys_uart_d
[    1.032224] clk: Disabled unused clock: t7_sys_uart_c
[    1.032857] clk: Disabled unused clock: t7_sys_uart_b
[    1.033482] clk: Disabled unused clock: t7_sys_eth
[    1.034077] clk: Disabled unused clock: t7_sys_audio
[    1.034694] clk: Disabled unused clock: t7_sys_ir_ctrl
[    1.035333] clk: Disabled unused clock: t7_sys_msr_clk
[    1.035972] clk: Disabled unused clock: t7_sys_spifc
[    1.036596] clk: Disabled unused clock: t7_sys_acodec
[    1.037218] clk: Disabled unused clock: t7_sys_smartcard
[    1.037880] clk: Disabled unused clock: t7_sys_am2axi2
[    1.038518] clk: Disabled unused clock: t7_sys_am2axi1
[    1.039157] clk: Disabled unused clock: t7_sys_am2axi0
[    1.039796] clk: Disabled unused clock: t7_sys_ampipe_eth
[    1.040468] clk: Disabled unused clock: t7_sys_ampipe_nand
[    1.041155] clk: Disabled unused clock: t7_sys_deswarp
[    1.041790] clk: Disabled unused clock: t7_sys_gdc
[    1.042385] clk: Disabled unused clock: t7_sys_cec
[    1.042981] clk: Disabled unused clock: t7_sys_aucpu
[    1.043600] clk: Disabled unused clock: t7_sys_aocpu
[    1.044217] clk: Disabled unused clock: t7_sys_mali
[    1.044830] clk: Disabled unused clock: t7_sys_ethphy
[    1.045451] clk: Disabled unused clock: t7_sys_mipi_dsi_b
[    1.046123] clk: Disabled unused clock: t7_sys_mipi_dsi_a
[    1.046795] clk: Disabled unused clock: t7_sys_dos
[    1.047390] clk: Disabled unused clock: t7_sys_ddr
[    1.047991] clk: Disabled unused clock: pwm_ao_g
[    1.048565] clk: Disabled unused clock: pwm_ao_f
[    1.049135] clk: Disabled unused clock: pwm_ao_e
[    1.049709] clk: Disabled unused clock: pwm_ao_d
[    1.050283] clk: Disabled unused clock: pwm_ao_b
[    1.050857] clk: Disabled unused clock: pwm_ao_a
[    1.051454] clk: Disabled unused clock: rtc_dualdiv
[    1.052038] clk: Disabled unused clock: rtc_duandiv_in

Also with the patches the disable happens 0.5 second later, from 0.5 
seconds after the boot to 1 second after the boot.

I am still investigating what is missing a consumer or what should be 
labeled critical.

thanks
Lucas Tanure