From 436d34f450818469fe8e09c177ee46e685ec47a7 Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Date: Wed, 27 Apr 2022 17:47:14 -0500
Subject: drm/i915: Fix -Wstringop-overflow warning in call to
 intel_read_wm_latency()
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Git-commit: 336feb502a715909a8136eb6a62a83d7268a353b
Patch-mainline: v5.19-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

Fix the following -Wstringop-overflow warnings when building with GCC-11:

drivers/gpu/drm/i915/intel_pm.c:3106:9: warning: ‘intel_read_wm_latency’ accessing 16 bytes in a region of size 10 [-Wstringop-overflow=]
 3106 |         intel_read_wm_latency(dev_priv, dev_priv->wm.pri_latency);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/i915/intel_pm.c:3106:9: note: referencing argument 2 of type ‘u16 *’ {aka ‘short unsigned int *’}
drivers/gpu/drm/i915/intel_pm.c:2861:13: note: in a call to function ‘intel_read_wm_latency’
 2861 | static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
      |             ^~~~~~~~~~~~~~~~~~~~~

by removing the over-specified array size from the argument declarations.

It seems that this code is actually safe because the size of the
array depends on the hardware generation, and the function checks
for that.

Notice that wm can be an array of 5 elements:
drivers/gpu/drm/i915/intel_pm.c:3109:   intel_read_wm_latency(dev_priv, dev_priv->wm.pri_latency);

or an array of 8 elements:
drivers/gpu/drm/i915/intel_pm.c:3131:   intel_read_wm_latency(dev_priv, dev_priv->wm.skl_latency);

and the compiler legitimately complains about that.

This helps with the ongoing efforts to globally enable
-Wstringop-overflow.

Link: https://github.com/KSPP/linux/issues/181
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/intel_pm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 9333f732cda8..5167d63010b9 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2859,7 +2859,7 @@ static void ilk_compute_wm_level(const struct drm_i915_private *dev_priv,
 }
 
 static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
-				  u16 wm[8])
+				  u16 wm[])
 {
 	struct intel_uncore *uncore = &dev_priv->uncore;
 
-- 
2.38.1