linux-kernel - [PATCH AUTOSEL 6.11 30/32] drm/xe: Handle unreliable MMIO reads during forcewake

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Message-ID: <20241028105050.3559169-30-sashal@kernel.org>
Date: Mon, 28 Oct 2024 06:50:12 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Shuicheng Lin <shuicheng.lin@...el.com>,
	Alex Zuo <alex.zuo@...el.com>,
	Matthew Brost <matthew.brost@...el.com>,
	Michal Wajdeczko <michal.wajdeczko@...el.com>,
	Himal Prasad Ghimiray <himal.prasad.ghimiray@...el.com>,
	Badal Nilawar <badal.nilawar@...el.com>,
	Anshuman Gupta <anshuman.gupta@...el.com>,
	Matt Roper <matthew.d.roper@...el.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Sasha Levin <sashal@...nel.org>,
	thomas.hellstrom@...ux.intel.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	intel-xe@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.11 30/32] drm/xe: Handle unreliable MMIO reads during forcewake

From: Shuicheng Lin <shuicheng.lin@...el.com>

[ 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@...el.com>
Signed-off-by: Shuicheng Lin <shuicheng.lin@...el.com>
Cc: Matthew Brost <matthew.brost@...el.com>
Cc: Michal Wajdeczko <michal.wajdeczko@...el.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@...el.com>
Acked-by: Badal Nilawar <badal.nilawar@...el.com>
Cc: Anshuman Gupta <anshuman.gupta@...el.com>
Cc: Matt Roper <matthew.d.roper@...el.com>
Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241017221547.1564029-1-shuicheng.lin@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
(cherry picked from commit a9fbeabe7226a3bf90f82d0e28a02c18e3c67447)
Signed-off-by: Lucas De Marchi <lucas.demarchi@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/xe/xe_force_wake.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

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;
 }
-- 
2.43.0