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[3.16.y-ckt,171/185] drm/tegra: dpaux: Fix transfers larger than 4 bytes

Message ID 1436951580-15977-172-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques July 15, 2015, 9:12 a.m. UTC 
3.16.7-ckt15 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thierry Reding <treding@nvidia.com>

commit 3c1dae0a07c651526f8e878d223a88f82caa5a50 upstream.

The DPAUX read/write FIFO registers aren't sequential in the register
space, causing transfers larger than 4 bytes to cause accesses to non-
existing FIFO registers.

Fixes: 6b6b604215c6 ("drm/tegra: Add eDP support")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/gpu/drm/tegra/dpaux.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)
diff mbox

Patch

diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index 708f783ead47..7fb27458444f 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -72,34 +72,32 @@  static inline void tegra_dpaux_writel(struct tegra_dpaux *dpaux,
 static void tegra_dpaux_write_fifo(struct tegra_dpaux *dpaux, const u8 *buffer,
 				   size_t size)
 {
-	unsigned long offset = DPAUX_DP_AUXDATA_WRITE(0);
 	size_t i, j;
 
-	for (i = 0; i < size; i += 4) {
-		size_t num = min_t(size_t, size - i, 4);
+	for (i = 0; i < DIV_ROUND_UP(size, 4); i++) {
+		size_t num = min_t(size_t, size - i * 4, 4);
 		unsigned long value = 0;
 
 		for (j = 0; j < num; j++)
-			value |= buffer[i + j] << (j * 8);
+			value |= buffer[i * 4 + j] << (j * 8);
 
-		tegra_dpaux_writel(dpaux, value, offset++);
+		tegra_dpaux_writel(dpaux, value, DPAUX_DP_AUXDATA_WRITE(i));
 	}
 }
 
 static void tegra_dpaux_read_fifo(struct tegra_dpaux *dpaux, u8 *buffer,
 				  size_t size)
 {
-	unsigned long offset = DPAUX_DP_AUXDATA_READ(0);
 	size_t i, j;
 
-	for (i = 0; i < size; i += 4) {
-		size_t num = min_t(size_t, size - i, 4);
+	for (i = 0; i < DIV_ROUND_UP(size, 4); i++) {
+		size_t num = min_t(size_t, size - i * 4, 4);
 		unsigned long value;
 
-		value = tegra_dpaux_readl(dpaux, offset++);
+		value = tegra_dpaux_readl(dpaux, DPAUX_DP_AUXDATA_READ(i));
 
 		for (j = 0; j < num; j++)
-			buffer[i + j] = value >> (j * 8);
+			buffer[i * 4 + j] = value >> (j * 8);
 	}
 }