drm/i915: Fix -Wstringop-overflow warning in call to intel_read_wm_latency()

commit 336feb502a715909a8136eb6a62a83d7268a353b upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index e43a76b027a2a93ea0b70b2891b863ce9409eadc..d59455b2d401f9469acd31080088cd5901d6036e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2822,7 +2822,7 @@ hsw_compute_linetime_wm(const struct intel_crtc_state *crtc_state)
 }
 
 static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
-                                 u16 wm[8])
+                                 u16 wm[])
 {
        struct intel_uncore *uncore = &dev_priv->uncore;