Re: [PATCH 1/8] OMAP: DSS2: DISPC: Fix minimum PCD value

[Archit Taneja <archit@ti.com>]

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.valkeinen@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,