[PATCH 01/13] drm/gma500: Sanity-check pipe index

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

If the DSI output isn't connected, then mdfld_dsi_encoder_get_pipe()
will return -1. The mdfld_dsi_dp_mode_set() function doesn't properly
check for this condition and causes the following compiler warnings:

	  CC      drivers/gpu/drm/gma500/mdfld_dsi_dpi.o
	drivers/gpu/drm/gma500/mdfld_dsi_dpi.c: In function ‘mdfld_dsi_dpi_mode_set’:
	drivers/gpu/drm/gma500/mdfld_dsi_dpi.c:828:35: warning: array subscript is below array bounds [-Warray-bounds]
	  u32 pipeconf = dev_priv->pipeconf[pipe];
	                                   ^
	drivers/gpu/drm/gma500/mdfld_dsi_dpi.c:829:33: warning: array subscript is below array bounds [-Warray-bounds]
	  u32 dspcntr = dev_priv->dspcntr[pipe];
	                                 ^

Fix this by checking for a valid pipe before indexing the pipeconf and
dspcntr arrays.

Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/gpu/drm/gma500/mdfld_dsi_dpi.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/gma500/mdfld_dsi_dpi.c b/drivers/gpu/drm/gma500/mdfld_dsi_dpi.c
index d4813e03f5ee..00275c3856ce 100644
--- a/drivers/gpu/drm/gma500/mdfld_dsi_dpi.c
+++ b/drivers/gpu/drm/gma500/mdfld_dsi_dpi.c
@@ -821,14 +821,18 @@ void mdfld_dsi_dpi_mode_set(struct drm_encoder *encoder,
 	struct drm_device *dev = dsi_config->dev;
 	struct drm_psb_private *dev_priv = dev->dev_private;
 	int pipe = mdfld_dsi_encoder_get_pipe(dsi_encoder);
-
 	u32 pipeconf_reg = PIPEACONF;
 	u32 dspcntr_reg = DSPACNTR;
+	u32 pipeconf, dspcntr;
 
-	u32 pipeconf = dev_priv->pipeconf[pipe];
-	u32 dspcntr = dev_priv->dspcntr[pipe];
 	u32 mipi = MIPI_PORT_EN | PASS_FROM_SPHY_TO_AFE | SEL_FLOPPED_HSTX;
 
+	if (WARN_ON(pipe < 0))
+		return;
+
+	pipeconf = dev_priv->pipeconf[pipe];
+	dspcntr = dev_priv->dspcntr[pipe];
+
 	if (pipe) {
 		pipeconf_reg = PIPECCONF;
 		dspcntr_reg = DSPCCNTR;
-- 
2.4.5

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