[PATCH] drm/amdgpu: add mb for si

[Christian König]

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 at 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;
>