On Tue, 2012-03-27 at 16:44 +0530, Mahapatra, Chandrabhanu wrote: > On Tue, Mar 27, 2012 at 4:33 PM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: > > On Wed, 2012-03-21 at 15:22 +0530, Chandrabhanu Mahapatra wrote: > >> DISPC_FCLK is incorrectly used as functional clock of DISPC in scaling > >> calculations. So, DISPC_CORE_CLK replaces as functional clock of DISPC. > >> DISPC_CORE_CLK is derived from DISPC_FCLK divided by an independent DISPC > >> divisor LCD. > >> > >> Signed-off-by: Chandrabhanu Mahapatra <cmahapatra@xxxxxx> > >> --- > >> drivers/video/omap2/dss/dispc.c | 13 +++++++------ > >> 1 files changed, 7 insertions(+), 6 deletions(-) > >> > >> diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c > >> index d8a1672..1fdac73 100644 > >> --- a/drivers/video/omap2/dss/dispc.c > >> +++ b/drivers/video/omap2/dss/dispc.c > >> @@ -1761,6 +1761,7 @@ static int dispc_ovl_calc_scaling(enum omap_plane plane, > >> dss_feat_get_param_max(FEAT_PARAM_LINEWIDTH); > >> const int max_decim_limit = 16; > >> unsigned long fclk = 0; > >> + unsigned long dispc_core_clk = dispc_mgr_lclk_rate(channel); > > > > Hmm, I don't think this is correct. dispc_mgr_lclk_rate() returns the > > logic clock for the LCD output path. It's not DISPC core clock. > > > > Tomi > > > > As per the OMAP4 TRM DISPC_CORE_CLK is DISPC_FCLK / LCD factor and Hmm? No it isn't. DISPC_CORE_CLK is DISPC_FCLK / LCD, where LCD is defined in DISPC_DIVISOR register. dispc_mgr_lclk_rate() returns the logic clock of an output, which is LCD1_CLK / LCD1 or LCD2_CLK / LCD2. And LCD1 and LCD2 are defined in DISPC_DIVISORo(n) register. (Very confusing to have LCD mean a liquid-crystal-display and also logic-clock-divisor =) I think we should rename them. Perhaps LCKD and PCKD). So the clocks for DISPC and for LCD outputs are totally separate ones, on OMAP4. For OMAP2/3 they are the same. That said, I have no idea which of the clock is used for what regarding scaling calculations, and even less do I know how it's managed for TV-out... > dispc_mgr_lclk_rate() exactly does the same. Should we rename the > function or have a separate fucntion for dispc_core_clk to avoid > confusion? I think we definitely should have a separate function, as it's a separate clock. And I guess the places where FCKs and LCKs are used should be verified so that they use the correct one. If somebody knows what is the correct one (the TRM is a bit vague at times =). Tomi
Attachment:
signature.asc
Description: This is a digitally signed message part
