Re: [PATCH] coresight: Disable MMIO logging for coresight stm driver

[Jinlong Mao <quic_jinlmao@quicinc.com>]

On 2025/4/30 21:51, Suzuki K Poulose wrote:
> Hi,
> 
> On 30/04/2025 12:03, Mao Jinlong wrote:
>> When read/write registers with readl_relaxed and writel_relaxed,
>> log_read_mmio and log_write_mmio will be called. If mmio trace
>> is enabled to STM, STM driver will write the register to send the
>> trace and writel_relaxed will be called again. The circular call
>> like callstack below will happen. Disable mmio logging for stm
>> driver to avoid this issue.
>>
> 
> Thanks for the fix, looks good to me. However, I think the commit 
> description is a bit cryptic. Could we say :
> 
> With MMIO logging enabled, the MMIO access are traced and could be
> sent to an STM device. Thus, an STM driver MMIO access could create
> circular call chain with MMIO logging. Disable it for STM driver.
> 
> Suzuki

I will update it.

> 
>> [] stm_source_write[stm_core]+0xc4
>> [] stm_ftrace_write[stm_ftrace]+0x40
>> [] trace_event_buffer_commit+0x238
>> [] trace_event_raw_event_rwmmio_rw_template+0x8c
>> [] log_post_write_mmio+0xb4
>> [] writel_relaxed[coresight_stm]+0x80
>> [] stm_generic_packet[coresight_stm]+0x1a8
>> [] stm_data_write[stm_core]+0x78
>> [] ost_write[stm_p_ost]+0xc8
>> [] stm_source_write[stm_core]+0x7c
>> [] stm_ftrace_write[stm_ftrace]+0x40
>> [] trace_event_buffer_commit+0x238
>> [] trace_event_raw_event_rwmmio_read+0x84
>> [] log_read_mmio+0xac
>> [] readl_relaxed[coresight_tmc]+0x50
>>
>> Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>
>> ---
>>   drivers/hwtracing/coresight/Makefile | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/ 
>> coresight/Makefile
>> index 4ba478211b31..f3158266f75e 100644
>> --- a/drivers/hwtracing/coresight/Makefile
>> +++ b/drivers/hwtracing/coresight/Makefile
>> @@ -22,6 +22,8 @@ condflags := \
>>       $(call cc-option, -Wstringop-truncation)
>>   subdir-ccflags-y += $(condflags)
>> +CFLAGS_coresight-stm.o := -D__DISABLE_TRACE_MMIO__
>> +
>>   obj-$(CONFIG_CORESIGHT) += coresight.o
>>   coresight-y := coresight-core.o  coresight-etm-perf.o coresight- 
>> platform.o \
>>           coresight-sysfs.o coresight-syscfg.o coresight-config.o \
>