[AMD Official Use Only]
>-----Original Message-----
>From: Koenig, Christian <Christian.Koenig@xxxxxxx>
>Sent: Wednesday, December 1, 2021 5:30 PM
>To: Yu, Lang <Lang.Yu@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
>Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Lazar, Lijo
><Lijo.Lazar@xxxxxxx>; Huang, Ray <Ray.Huang@xxxxxxx>
>Subject: Re: [PATCH] drm/amdgpu: add support to SMU debug option
>
>Am 01.12.21 um 10:24 schrieb Lang Yu:
>> To maintain system error state when SMU errors occurred, which will
>> aid in debugging SMU firmware issues, add SMU debug option support.
>>
>> It can be enabled or disabled via amdgpu_smu_debug debugfs file. When
>> enabled, it makes SMU errors fatal.
>> It is disabled by default.
>>
>> == Command Guide ==
>>
>> 1, enable SMU debug option
>>
>> # echo 1 > /sys/kernel/debug/dri/0/amdgpu_smu_debug
>>
>> 2, disable SMU debug option
>>
>> # echo 0 > /sys/kernel/debug/dri/0/amdgpu_smu_debug
>>
>> v3:
>> - Use debugfs_create_bool().(Christian)
>> - Put variable into smu_context struct.
>> - Don't resend command when timeout.
>>
>> v2:
>> - Resend command when timeout.(Lijo)
>> - Use debugfs file instead of module parameter.
>>
>> Signed-off-by: Lang Yu <lang.yu@xxxxxxx>
>
>Well the debugfs part looks really nice and clean now, but one more comment
>below.
>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 3 +++
>> drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h | 5 +++++
>> drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c | 2 ++
>> drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c | 8 +++++++-
>> 4 files changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>> index 164d6a9e9fbb..86cd888c7822 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>> @@ -1618,6 +1618,9 @@ int amdgpu_debugfs_init(struct amdgpu_device
>*adev)
>> if (!debugfs_initialized())
>> return 0;
>>
>> + debugfs_create_bool("amdgpu_smu_debug", 0600, root,
>> + &adev->smu.smu_debug_mode);
>> +
>> ent = debugfs_create_file("amdgpu_preempt_ib", 0600, root, adev,
>> &fops_ib_preempt);
>> if (IS_ERR(ent)) {
>> diff --git a/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
>> b/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
>> index f738f7dc20c9..50dbf5594a9d 100644
>> --- a/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
>> +++ b/drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h
>> @@ -569,6 +569,11 @@ struct smu_context
>> struct smu_user_dpm_profile user_dpm_profile;
>>
>> struct stb_context stb_context;
>> + /*
>> + * When enabled, it makes SMU errors fatal.
>> + * (0 = disabled (default), 1 = enabled)
>> + */
>> + bool smu_debug_mode;
>> };
>>
>> struct i2c_adapter;
>> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c
>> b/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c
>> index 6e781cee8bb6..d3797a2d6451 100644
>> --- a/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c
>> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c
>> @@ -1919,6 +1919,8 @@ static int aldebaran_mode2_reset(struct
>smu_context *smu)
>> out:
>> mutex_unlock(&smu->message_lock);
>>
>> + BUG_ON(unlikely(smu->smu_debug_mode) && ret);
>> +
>> return ret;
>> }
>>
>> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
>> b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
>> index 048ca1673863..9be005eb4241 100644
>> --- a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
>> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
>> @@ -349,15 +349,21 @@ int smu_cmn_send_smc_msg_with_param(struct
>smu_context *smu,
>> __smu_cmn_reg_print_error(smu, reg, index, param, msg);
>> goto Out;
>> }
>> +
>> __smu_cmn_send_msg(smu, (uint16_t) index, param);
>> reg = __smu_cmn_poll_stat(smu);
>> res = __smu_cmn_reg2errno(smu, reg);
>> - if (res != 0)
>> + if (res != 0) {
>> __smu_cmn_reg_print_error(smu, reg, index, param, msg);
>> + goto Out;
>> + }
>> if (read_arg)
>> smu_cmn_read_arg(smu, read_arg);
>> Out:
>> mutex_unlock(&smu->message_lock);
>> +
>> + BUG_ON(unlikely(smu->smu_debug_mode) && res);
>
>BUG_ON() really crashes the kernel and is only allowed if we prevent further data
>corruption with that.
>
>Most of the time WARN_ON() is more appropriate, but I can't fully judge here
>since I don't know the SMU code well enough.
This is what SMU FW guys want. They want "user-visible (potentially fatal) errors", then a hang.
They want to keep system state since the error occurred.
Regards,
Lang
>Christian.
>
>> +
>> return res;
>> }
>>
