From 76589bcc73f477ef2b3b90e4fae6a7a4dfd925af Mon Sep 17 00:00:00 2001 From: Shubhankar Milind Sardeshpande Date: Thu, 21 May 2026 10:55:18 +0530 Subject: [PATCH] drm/amd/pm: re-enable MC access after PrepareMp1ForUnload on SMU V15 APUs During smu_v15_0_0_system_features_control(), the driver sends a PrepareMp1ForUnload message to PMFW. PMFW then performs nBIF and SYSHUB function-level resets (FLR), disabling PCIe CFG space reset, which clears the framebuffer enable bit to zero and disables MC (memory controller) access from the host. Re-enable MC access via the nbio mc_access_enable callback right after PrepareMp1ForUnload completes in smu_v15_0_0_system_features_control(). Signed-off-by: Shubhankar Milind Sardeshpande Signed-off-by: Suresh Guttula Signed-off-by: Alex Deucher (cherry picked from commit 840a3c5aeae779a3bc75d7f747c3ed18b1af6507) Cc: stable@vger.kernel.org --- drivers/gpu/drm/amd/pm/swsmu/smu15/smu_v15_0_0_ppt.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu15/smu_v15_0_0_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu15/smu_v15_0_0_ppt.c index fb1145691410f..a214ddbd4c863 100644 --- a/drivers/gpu/drm/amd/pm/swsmu/smu15/smu_v15_0_0_ppt.c +++ b/drivers/gpu/drm/amd/pm/swsmu/smu15/smu_v15_0_0_ppt.c @@ -227,9 +227,14 @@ static int smu_v15_0_0_system_features_control(struct smu_context *smu, bool en) struct amdgpu_device *adev = smu->adev; int ret = 0; - if (!en && !adev->in_s0ix) + if (!en && !adev->in_s0ix) { ret = smu_cmn_send_smc_msg(smu, SMU_MSG_PrepareMp1ForUnload, NULL); + /* SMU resets BIF_FB_EN to zero, re-enable MC access on APUs with SMU V15 */ + if (!ret && adev->nbio.funcs && adev->nbio.funcs->mc_access_enable) + adev->nbio.funcs->mc_access_enable(adev, true); + } + return ret; } -- 2.47.3