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Date:   Fri, 18 Nov 2022 10:18:14 +0100
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Subject: Re: [PATCH] drm/amdgpu: add mb for si
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To:     =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Zhenneng Li <lizhenneng@kylinos.cn>,
        Alex Deucher <alexander.deucher@amd.com>
Cc:     Xinhui.Pan@amd.com, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org
References: <20221118074810.380368-1-lizhenneng@kylinos.cn>
 <ecd9d251-8941-b2db-71b2-e4ac06f860a3@amd.com>
From:   =?UTF-8?Q?Michel_D=c3=a4nzer?= <michel.daenzer@mailbox.org>
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On 11/18/22 09:01, Christian König wrote:
> Am 18.11.22 um 08:48 schrieb Zhenneng Li:
>> During reboot test on arm64 platform, it may failure on boot,
>> so add this mb in smc.
>>
>> The error message are as follows:
>> [    6.996395][ 7] [  T295] [drm:amdgpu_device_ip_late_init [amdgpu]] *ERROR*
>>                 late_init of IP block <si_dpm> failed -22
>> [    7.006919][ 7] [  T295] amdgpu 0000:04:00.0: amdgpu_device_ip_late_init failed
>> [    7.014224][ 7] [  T295] amdgpu 0000:04:00.0: Fatal error during GPU init
> 
> Memory barries are not supposed to be sprinkled around like this, you need to give a detailed explanation why this is necessary.
> 
> Regards,
> Christian.
> 
>>
>> Signed-off-by: Zhenneng Li <lizhenneng@kylinos.cn>
>> ---
>>   drivers/gpu/drm/amd/pm/legacy-dpm/si_smc.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/pm/legacy-dpm/si_smc.c b/drivers/gpu/drm/amd/pm/legacy-dpm/si_smc.c
>> index 8f994ffa9cd1..c7656f22278d 100644
>> --- a/drivers/gpu/drm/amd/pm/legacy-dpm/si_smc.c
>> +++ b/drivers/gpu/drm/amd/pm/legacy-dpm/si_smc.c
>> @@ -155,6 +155,8 @@ bool amdgpu_si_is_smc_running(struct amdgpu_device *adev)
>>       u32 rst = RREG32_SMC(SMC_SYSCON_RESET_CNTL);
>>       u32 clk = RREG32_SMC(SMC_SYSCON_CLOCK_CNTL_0);
>>   +    mb();
>> +
>>       if (!(rst & RST_REG) && !(clk & CK_DISABLE))
>>           return true;

In particular, it makes no sense in this specific place, since it cannot directly affect the values of rst & clk.


-- 
Earthling Michel Dänzer            |                  https://redhat.com
Libre software enthusiast          |         Mesa and Xwayland developer