Re: [RESEND 3/3] drm/amd/display: switch to guid_gen() to generate valid GUIDs

[Hamza Mahfooz <hamza.mahfooz@amd.com>]

On 8/12/24 08:23, Jani Nikula wrote:
> Instead of just smashing jiffies into a GUID, use guid_gen() to generate
> RFC 4122 compliant GUIDs.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> 
> ---

Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>

I would prefer to take this series through the amdgpu tree though,
assuming nobody minds.

> 
> Side note, it baffles me why amdgpu has a copy of this instead of
> plumbing it into drm mst code.
> ---
>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 23 ++++++++++---------
>   1 file changed, 12 insertions(+), 11 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 72c10fc2c890..ce05e7e2a383 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -2568,9 +2568,9 @@ static int dm_late_init(void *handle)
>   
>   static void resume_mst_branch_status(struct drm_dp_mst_topology_mgr *mgr)
>   {
> +	u8 buf[UUID_SIZE];
> +	guid_t guid;
>   	int ret;
> -	u8 guid[16];
> -	u64 tmp64;
>   
>   	mutex_lock(&mgr->lock);
>   	if (!mgr->mst_primary)
> @@ -2591,26 +2591,27 @@ static void resume_mst_branch_status(struct drm_dp_mst_topology_mgr *mgr)
>   	}
>   
>   	/* Some hubs forget their guids after they resume */
> -	ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
> -	if (ret != 16) {
> +	ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, buf, sizeof(buf));
> +	if (ret != sizeof(buf)) {
>   		drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
>   		goto out_fail;
>   	}
>   
> -	if (memchr_inv(guid, 0, 16) == NULL) {
> -		tmp64 = get_jiffies_64();
> -		memcpy(&guid[0], &tmp64, sizeof(u64));
> -		memcpy(&guid[8], &tmp64, sizeof(u64));
> +	import_guid(&guid, buf);
>   
> -		ret = drm_dp_dpcd_write(mgr->aux, DP_GUID, guid, 16);
> +	if (guid_is_null(&guid)) {
> +		guid_gen(&guid);
> +		export_guid(buf, &guid);
>   
> -		if (ret != 16) {
> +		ret = drm_dp_dpcd_write(mgr->aux, DP_GUID, buf, sizeof(buf));
> +
> +		if (ret != sizeof(buf)) {
>   			drm_dbg_kms(mgr->dev, "check mstb guid failed - undocked during suspend?\n");
>   			goto out_fail;
>   		}
>   	}
>   
> -	import_guid(&mgr->mst_primary->guid, guid);
> +	guid_copy(&mgr->mst_primary->guid, &guid);
>   
>   out_fail:
>   	mutex_unlock(&mgr->lock);
-- 
Hamza