Patch "drm/xe: Handle unreliable MMIO reads during forcewake" has been added to the 6.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/xe: Handle unreliable MMIO reads during forcewake

to the 6.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-xe-handle-unreliable-mmio-reads-during-forcewake.patch
and it can be found in the queue-6.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fde7df4e95b9569fd290013b6186f0b5010fd50d
Author: Shuicheng Lin <shuicheng.lin@xxxxxxxxx>
Date:   Thu Oct 17 22:15:47 2024 +0000

    drm/xe: Handle unreliable MMIO reads during forcewake
    
    [ Upstream commit 69418db678567bdf9a4992c83d448da462ffa78c ]
    
    In some cases, when the driver attempts to read an MMIO register,
    the hardware may return 0xFFFFFFFF. The current force wake path
    code treats this as a valid response, as it only checks the BIT.
    However, 0xFFFFFFFF should be considered an invalid value, indicating
    a potential issue. To address this, we should add a log entry to
    highlight this condition and return failure.
    The force wake failure log level is changed from notice to err
    to match the failure return value.
    
    v2 (Matt Brost):
      - set ret value (-EIO) to kick the error to upper layers
    v3 (Rodrigo):
      - add commit message for the log level promotion from notice to err
    v4:
      - update reviewed info
    
    Suggested-by: Alex Zuo <alex.zuo@xxxxxxxxx>
    Signed-off-by: Shuicheng Lin <shuicheng.lin@xxxxxxxxx>
    Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
    Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
    Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@xxxxxxxxx>
    Acked-by: Badal Nilawar <badal.nilawar@xxxxxxxxx>
    Cc: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
    Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
    Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
    Link: https://patchwork.freedesktop.org/patch/msgid/20241017221547.1564029-1-shuicheng.lin@xxxxxxxxx
    Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
    (cherry picked from commit a9fbeabe7226a3bf90f82d0e28a02c18e3c67447)
    Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/xe/xe_force_wake.c b/drivers/gpu/drm/xe/xe_force_wake.c
index b263fff152737..7d9fc489dcb81 100644
--- a/drivers/gpu/drm/xe/xe_force_wake.c
+++ b/drivers/gpu/drm/xe/xe_force_wake.c
@@ -115,9 +115,15 @@ static int __domain_wait(struct xe_gt *gt, struct xe_force_wake_domain *domain,
 			     XE_FORCE_WAKE_ACK_TIMEOUT_MS * USEC_PER_MSEC,
 			     &value, true);
 	if (ret)
-		xe_gt_notice(gt, "Force wake domain %d failed to ack %s (%pe) reg[%#x] = %#x\n",
-			     domain->id, str_wake_sleep(wake), ERR_PTR(ret),
-			     domain->reg_ack.addr, value);
+		xe_gt_err(gt, "Force wake domain %d failed to ack %s (%pe) reg[%#x] = %#x\n",
+			  domain->id, str_wake_sleep(wake), ERR_PTR(ret),
+			  domain->reg_ack.addr, value);
+	if (value == ~0) {
+		xe_gt_err(gt,
+			  "Force wake domain %d: %s. MMIO unreliable (forcewake register returns 0xFFFFFFFF)!\n",
+			  domain->id, str_wake_sleep(wake));
+		ret = -EIO;
+	}
 
 	return ret;
 }