On Wednesday 31 August 2011 06:51 PM, Valkeinen, Tomi wrote:
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.

This looks good to me.

Archit


Signed-off-by: Tomi Valkeinen<tomi.valkei...@ti.com>
---
  drivers/video/omap2/dss/dispc.c        |   14 ++++++++++----
  drivers/video/omap2/dss/dss_features.c |    3 +++
  drivers/video/omap2/dss/dss_features.h |    1 +
  3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index de20936..7f3d847 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -2339,7 +2339,7 @@ static void dispc_mgr_set_lcd_divisor(enum omap_channel 
channel, u16 lck_div,
                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));
@@ -2726,11 +2726,17 @@ void dispc_mgr_set_pol_freq(enum omap_channel channel,
  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;
@@ -2738,7 +2744,7 @@ void dispc_find_clk_divs(bool is_tft, unsigned long 
req_pck, unsigned long fck,
        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);
@@ -2773,7 +2779,7 @@ int dispc_calc_clock_rates(unsigned long dispc_fclk_rate,
  {
        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;
diff --git a/drivers/video/omap2/dss/dss_features.c 
b/drivers/video/omap2/dss/dss_features.c
index b63c5f8..85b07ca 100644
--- a/drivers/video/omap2/dss/dss_features.c
+++ b/drivers/video/omap2/dss/dss_features.c
@@ -281,6 +281,7 @@ static const char * const omap4_dss_clk_source_names[] = {

  static const struct dss_param_range omap2_dss_param_range[] = {
        [FEAT_PARAM_DSS_FCK]                    = { 0, 173000000 },
+       [FEAT_PARAM_DSS_PCD]                    = { 2, 255 },
        [FEAT_PARAM_DSIPLL_REGN]                = { 0, 0 },
        [FEAT_PARAM_DSIPLL_REGM]                = { 0, 0 },
        [FEAT_PARAM_DSIPLL_REGM_DISPC]          = { 0, 0 },
@@ -291,6 +292,7 @@ static const struct dss_param_range omap2_dss_param_range[] 
= {

  static const struct dss_param_range omap3_dss_param_range[] = {
        [FEAT_PARAM_DSS_FCK]                    = { 0, 173000000 },
+       [FEAT_PARAM_DSS_PCD]                    = { 1, 255 },
        [FEAT_PARAM_DSIPLL_REGN]                = { 0, (1<<  7) - 1 },
        [FEAT_PARAM_DSIPLL_REGM]                = { 0, (1<<  11) - 1 },
        [FEAT_PARAM_DSIPLL_REGM_DISPC]          = { 0, (1<<  4) - 1 },
@@ -301,6 +303,7 @@ static const struct dss_param_range omap3_dss_param_range[] 
= {

  static const struct dss_param_range omap4_dss_param_range[] = {
        [FEAT_PARAM_DSS_FCK]                    = { 0, 186000000 },
+       [FEAT_PARAM_DSS_PCD]                    = { 1, 255 },
        [FEAT_PARAM_DSIPLL_REGN]                = { 0, (1<<  8) - 1 },
        [FEAT_PARAM_DSIPLL_REGM]                = { 0, (1<<  12) - 1 },
        [FEAT_PARAM_DSIPLL_REGM_DISPC]          = { 0, (1<<  5) - 1 },
diff --git a/drivers/video/omap2/dss/dss_features.h 
b/drivers/video/omap2/dss/dss_features.h
index 4271e96..158d922 100644
--- a/drivers/video/omap2/dss/dss_features.h
+++ b/drivers/video/omap2/dss/dss_features.h
@@ -73,6 +73,7 @@ enum dss_feat_reg_field {

  enum dss_range_param {
        FEAT_PARAM_DSS_FCK,
+       FEAT_PARAM_DSS_PCD,
        FEAT_PARAM_DSIPLL_REGN,
        FEAT_PARAM_DSIPLL_REGM,
        FEAT_PARAM_DSIPLL_REGM_DISPC,

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