OMAP: DSS2: Fix FIFO threshold and burst size for OMAP4

The DMA FIFO threshold registers and burst size registers have changed
for OMAP4.  The current code only handles OMAP2/3 case, and so the
values are a bit off for OMAP4.  A summary of the differences between
OMAP2/3 and OMAP4:

Burst size:
OMAP2/3: 4 x 32 bits / 8 x 32 bits / 16 x 32 bits
OMAP4: 2 x 128 bits / 4 x 128 bits / 8 x 128 bits

Threshold size:
OMAP2/3: in bytes (8 bit units)
OMAP4: in 128bit units

This patch fixes the issue by creating two new helper functions in
dss_features: dss_feat_get_buffer_size_unit() and
dss_feat_get_burst_size_unit(). These return (in bytes) the unit size
for threshold registers and unit size for burst size register,
respectively, and are used to calculate correct values.

For the threshold size the usage is straightforward. However, the burst
size register has different multipliers for OMAP2/3 and OMAP4. This
patch solves the problem by defining the multipliers for the burst size
as 2x, 4x and 8x, which fit fine for the OMAP4 burst size definition
(i.e. burst size unit for OMAP4 is 128bits), but requires a slight twist
on OMAP2/3 by defining the burst size unit as 64bit.

As the driver in practice always uses the maximum burst size, and no use
case currently exists where we would want to use a smaller burst size,
this patch changes the driver to hardcode the burst size when
initializing DISPC. This makes the threshold configuration code somewhat
simpler.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 42 insertions, 8 deletions

diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index 1abed77e989..ba1ccf709e1 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -78,6 +78,12 @@ struct dispc_v_coef {
 	s8 vc00;
 };
 
+enum omap_burst_size {
+	BURST_SIZE_X2 = 0,
+	BURST_SIZE_X4 = 1,
+	BURST_SIZE_X8 = 2,
+};
+
 #define REG_GET(idx, start, end) \
 	FLD_GET(dispc_read_reg(idx), start, end)
 
@@ -992,11 +998,10 @@ static void _dispc_set_channel_out(enum omap_plane plane,
 	dispc_write_reg(DISPC_OVL_ATTRIBUTES(plane), val);
 }
 
-void dispc_set_burst_size(enum omap_plane plane,
+static void dispc_set_burst_size(enum omap_plane plane,
 		enum omap_burst_size burst_size)
 {
 	int shift;
-	u32 val;
 
 	enable_clocks(1);
 
@@ -1013,13 +1018,28 @@ void dispc_set_burst_size(enum omap_plane plane,
 		return;
 	}
 
-	val = dispc_read_reg(DISPC_OVL_ATTRIBUTES(plane));
-	val = FLD_MOD(val, burst_size, shift+1, shift);
-	dispc_write_reg(DISPC_OVL_ATTRIBUTES(plane), val);
+	REG_FLD_MOD(DISPC_OVL_ATTRIBUTES(plane), burst_size, shift + 1, shift);
 
 	enable_clocks(0);
 }
 
+static void dispc_configure_burst_sizes(void)
+{
+	int i;
+	const int burst_size = BURST_SIZE_X8;
+
+	/* Configure burst size always to maximum size */
+	for (i = 0; i < omap_dss_get_num_overlays(); ++i)
+		dispc_set_burst_size(i, burst_size);
+}
+
+u32 dispc_get_burst_size(enum omap_plane plane)
+{
+	unsigned unit = dss_feat_get_burst_size_unit();
+	/* burst multiplier is always x8 (see dispc_configure_burst_sizes()) */
+	return unit * 8;
+}
+
 void dispc_enable_gamma_table(bool enable)
 {
 	/*
@@ -1118,14 +1138,17 @@ static void dispc_read_plane_fifo_sizes(void)
 	u32 size;
 	int plane;
 	u8 start, end;
+	u32 unit;
+
+	unit = dss_feat_get_buffer_size_unit();
 
 	enable_clocks(1);
 
 	dss_feat_get_reg_field(FEAT_REG_FIFOSIZE, &start, &end);
 
 	for (plane = 0; plane < ARRAY_SIZE(dispc.fifo_size); ++plane) {
-		size = FLD_GET(dispc_read_reg(DISPC_OVL_FIFO_SIZE_STATUS(plane)),
-			start, end);
+		size = REG_GET(DISPC_OVL_FIFO_SIZE_STATUS(plane), start, end);
+		size *= unit;
 		dispc.fifo_size[plane] = size;
 	}
 
@@ -1137,9 +1160,18 @@ u32 dispc_get_plane_fifo_size(enum omap_plane plane)
 	return dispc.fifo_size[plane];
 }
 
-void dispc_setup_plane_fifo(enum omap_plane plane, u32 low, u32 high)
+void dispc_set_fifo_threshold(enum omap_plane plane, u32 low, u32 high)
 {
 	u8 hi_start, hi_end, lo_start, lo_end;
+	u32 unit;
+
+	unit = dss_feat_get_buffer_size_unit();
+
+	WARN_ON(low % unit != 0);
+	WARN_ON(high % unit != 0);
+
+	low /= unit;
+	high /= unit;
 
 	dss_feat_get_reg_field(FEAT_REG_FIFOHIGHTHRESHOLD, &hi_start, &hi_end);
 	dss_feat_get_reg_field(FEAT_REG_FIFOLOWTHRESHOLD, &lo_start, &lo_end);
@@ -3624,6 +3656,8 @@ static void _omap_dispc_initial_config(void)
 	dispc_set_loadmode(OMAP_DSS_LOAD_FRAME_ONLY);
 
 	dispc_read_plane_fifo_sizes();
+
+	dispc_configure_burst_sizes();
 }
 
 int dispc_enable_plane(enum omap_plane plane, bool enable)