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, 23 insertions, 0 deletions

diff --git a/drivers/video/omap2/dss/dss_features.c b/drivers/video/omap2/dss/dss_features.c
index bd420f9650c9..b415c4ee621d 100644
--- a/drivers/video/omap2/dss/dss_features.c
+++ b/drivers/video/omap2/dss/dss_features.c
@@ -49,6 +49,9 @@ struct omap_dss_features {
 	const enum omap_color_mode *supported_color_modes;
 	const char * const *clksrc_names;
 	const struct dss_param_range *dss_params;
+
+	const u32 buffer_size_unit;
+	const u32 burst_size_unit;
 };
 
 /* This struct is assigned to one of the below during initialization */
@@ -274,6 +277,8 @@ static const struct omap_dss_features omap2_dss_features = {
 	.supported_color_modes = omap2_dss_supported_color_modes,
 	.clksrc_names = omap2_dss_clk_source_names,
 	.dss_params = omap2_dss_param_range,
+	.buffer_size_unit = 1,
+	.burst_size_unit = 8,
 };
 
 /* OMAP3 DSS Features */
@@ -296,6 +301,8 @@ static const struct omap_dss_features omap3430_dss_features = {
 	.supported_color_modes = omap3_dss_supported_color_modes,
 	.clksrc_names = omap3_dss_clk_source_names,
 	.dss_params = omap3_dss_param_range,
+	.buffer_size_unit = 1,
+	.burst_size_unit = 8,
 };
 
 static const struct omap_dss_features omap3630_dss_features = {
@@ -317,6 +324,8 @@ static const struct omap_dss_features omap3630_dss_features = {
 	.supported_color_modes = omap3_dss_supported_color_modes,
 	.clksrc_names = omap3_dss_clk_source_names,
 	.dss_params = omap3_dss_param_range,
+	.buffer_size_unit = 1,
+	.burst_size_unit = 8,
 };
 
 /* OMAP4 DSS Features */
@@ -339,6 +348,8 @@ static const struct omap_dss_features omap4430_es1_0_dss_features  = {
 	.supported_color_modes = omap4_dss_supported_color_modes,
 	.clksrc_names = omap4_dss_clk_source_names,
 	.dss_params = omap4_dss_param_range,
+	.buffer_size_unit = 16,
+	.burst_size_unit = 16,
 };
 
 /* For all the other OMAP4 versions */
@@ -361,6 +372,8 @@ static const struct omap_dss_features omap4_dss_features = {
 	.supported_color_modes = omap4_dss_supported_color_modes,
 	.clksrc_names = omap4_dss_clk_source_names,
 	.dss_params = omap4_dss_param_range,
+	.buffer_size_unit = 16,
+	.burst_size_unit = 16,
 };
 
 /* Functions returning values related to a DSS feature */
@@ -406,6 +419,16 @@ const char *dss_feat_get_clk_source_name(enum omap_dss_clk_source id)
 	return omap_current_dss_features->clksrc_names[id];
 }
 
+u32 dss_feat_get_buffer_size_unit(void)
+{
+	return omap_current_dss_features->buffer_size_unit;
+}
+
+u32 dss_feat_get_burst_size_unit(void)
+{
+	return omap_current_dss_features->burst_size_unit;
+}
+
 /* DSS has_feature check */
 bool dss_has_feature(enum dss_feat_id id)
 {