Re: [PATCH] drm/amd/display: Fully switch to dmub for all dcn21 asics

["Limonciello, Mario" <mario.limonciello@amd.com>]

On 10/15/2021 17:31, Roman.Li@amd.com wrote:
> From: Roman Li <Roman.Li@amd.com>
> 
> [Why]
> On renoir usb-c port stops functioning on resume after f/w update.
> New dmub firmware caused regression due to conflict with dmcu.
> With new dmub f/w dmcu is superseded and should be disabled.
> 
> [How]
> - Disable dmcu for all dcn21.
> 
> Check dmesg for dmub f/w version.
> The old firmware (before regression):
> [drm] DMUB hardware initialized: version=0x00000001
> All other versions require that patch for renoir.
> 
> Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1735
> Cc: stable@vger.kernel.org

This won't backport cleanly to stable 5.15 and earlier don't use IP 
version to detect the chip.

Also - a question: *should* this go to stable?  If a user has the older 
FW what happens with this change?

> Signed-off-by: Roman Li <Roman.Li@amd.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index ff54550..e56f73e 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1356,8 +1356,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
>   		switch (adev->ip_versions[DCE_HWIP][0]) {
>   		case IP_VERSION(2, 1, 0):
>   			init_data.flags.gpu_vm_support = true;
> -			if (ASICREV_IS_GREEN_SARDINE(adev->external_rev_id))
> -				init_data.flags.disable_dmcu = true;
> +			init_data.flags.disable_dmcu = true;
>   			break;
>   		case IP_VERSION(1, 0, 0):
>   		case IP_VERSION(1, 0, 1):
>