OMAP: DSS2: DISPC: Fix minimum PCD value
The current driver had a hardcoded minimum value of 2 for pixel clock
divisor (PCD). This doesn't seem to be right.
OMAP4 TRM says that PCD can be 1 when not downscaling, and inverted
pixel clock (IPC) is off.
OMAP3 TRM says the same, but also in the register descriptions that PCD
value 1 is invalid.
OMAP2 TRM says PCD 2 is the minimum.
OMAP2 is still untested, but for both OMAP3 and OMAP4 PCD of 1 seems to
work fine.
This patch adds a new DSS feature, FEAT_PARAM_DSS_PCD, which is used to
find the minimum and maximum PCD. The minimum is set to 2 for OMAP2, and
1 for OMAP3/4.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index b4a16cf..4e9f87f 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -2334,7 +2334,7 @@
u16 pck_div)
{
BUG_ON(lck_div < 1);
- BUG_ON(pck_div < 2);
+ BUG_ON(pck_div < 1);
dispc_write_reg(DISPC_DIVISORo(channel),
FLD_VAL(lck_div, 23, 16) | FLD_VAL(pck_div, 7, 0));
@@ -2721,11 +2721,17 @@
void dispc_find_clk_divs(bool is_tft, unsigned long req_pck, unsigned long fck,
struct dispc_clock_info *cinfo)
{
- u16 pcd_min = is_tft ? 2 : 3;
+ u16 pcd_min, pcd_max;
unsigned long best_pck;
u16 best_ld, cur_ld;
u16 best_pd, cur_pd;
+ pcd_min = dss_feat_get_param_min(FEAT_PARAM_DSS_PCD);
+ pcd_max = dss_feat_get_param_max(FEAT_PARAM_DSS_PCD);
+
+ if (!is_tft)
+ pcd_min = 3;
+
best_pck = 0;
best_ld = 0;
best_pd = 0;
@@ -2733,7 +2739,7 @@
for (cur_ld = 1; cur_ld <= 255; ++cur_ld) {
unsigned long lck = fck / cur_ld;
- for (cur_pd = pcd_min; cur_pd <= 255; ++cur_pd) {
+ for (cur_pd = pcd_min; cur_pd <= pcd_max; ++cur_pd) {
unsigned long pck = lck / cur_pd;
long old_delta = abs(best_pck - req_pck);
long new_delta = abs(pck - req_pck);
@@ -2768,7 +2774,7 @@
{
if (cinfo->lck_div > 255 || cinfo->lck_div == 0)
return -EINVAL;
- if (cinfo->pck_div < 2 || cinfo->pck_div > 255)
+ if (cinfo->pck_div < 1 || cinfo->pck_div > 255)
return -EINVAL;
cinfo->lck = dispc_fclk_rate / cinfo->lck_div;