Hi Sriram,
On Wed, Dec 21, 2011 at 16:17:01, Madhvapathi Sriram wrote:
> Prakash,
>
> On Wed, Dec 21, 2011 at 12:57 PM, Manjunathappa, Prakash
> <prakash.pm@xxxxxx> wrote:
> >
> > LCDC functional clock may or may not be derived from CPU/MPU DPLL,
> > For example,
> > AM335x => Separate independent DPLL for LCDC
> > Davinci => Same DPLL as MPU
> >
> > So, on platforms where LCDC functional clock is not derived from CPU/MPU
> > PLL it is not required to reset LCDC module, if CPU frequency does not
> > change with DVFS.
> Is it not the case that the CPU frequency always changes during DVFS?
> This sentence does not strike me straight.
> Did you mean that if the frequency of the PLL (from which LCDC
> derives) does not change with DVFS, then LCDC module is not required
> to be reset?
Ok I will re-phrase it as below:
So, on platforms where LCDC functional clock is not derived from CPU/MPU
PLL it is not required to reset LCDC module as its functional clock does not change with DVFS.
> >
> > This patch adds check to do reset only if functional clock changes
> > between pre and post notifier callbacks with DVFS.
> >
> > Signed-off-by: Manjunathappa, Prakash <prakash.pm@xxxxxx>
> > ---
> > drivers/video/da8xx-fb.c | 13 ++++++++-----
> > 1 files changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/video/da8xx-fb.c b/drivers/video/da8xx-fb.c
> > index 29577bf..1334a68 100644
> > --- a/drivers/video/da8xx-fb.c
> > +++ b/drivers/video/da8xx-fb.c
> > @@ -161,6 +161,7 @@ struct da8xx_fb_par {
> > int vsync_timeout;
> > #ifdef CONFIG_CPU_FREQ
> > struct notifier_block freq_transition;
> > + unsigned int lcd_fck_rate;
> > #endif
> > void (*panel_power_ctrl)(int);
> > };
> > @@ -840,11 +841,12 @@ static int lcd_da8xx_cpufreq_transition(struct notifier_block *nb,
> > struct da8xx_fb_par *par;
> >
> > par = container_of(nb, struct da8xx_fb_par, freq_transition);
> > - if (val == CPUFREQ_PRECHANGE) {
> > - lcd_disable_raster();
> > - } else if (val == CPUFREQ_POSTCHANGE) {
> > - lcd_calc_clk_divider(par);
> > - lcd_enable_raster();
> > + if (val == CPUFREQ_POSTCHANGE) {
> > + if (par->lcd_fck_rate != clk_get_rate(par->lcdc_clk)) {
> > + lcd_disable_raster();
> > + lcd_calc_clk_divider(par);
> > + lcd_enable_raster();
> > + }
> > }
> >
> > return 0;
> > @@ -1137,6 +1139,7 @@ static int __devinit fb_probe(struct platform_device *device)
> >
> > par = da8xx_fb_info->par;
> > par->lcdc_clk = fb_clk;
> > + par->lcd_fck_rate = clk_get_rate(fb_clk);
> > par->pxl_clk = lcdc_info->pxl_clk;
> > if (fb_pdata->panel_power_ctrl) {
> > par->panel_power_ctrl = fb_pdata->panel_power_ctrl;
> > --
> > 1.7.1
> >
> > _______________________________________________
> > Davinci-linux-open-source mailing list
> > Davinci-linux-open-source@xxxxxxxxxxxxxxxxxxxx
> > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
>
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