[Intel-gfx] [RFC 3/3] drm/i915/icl: Calculate DPLL params for DSI

Mon Oct 1 12:29:23 UTC 2018

> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of
> Kulkarni, Vandita
> Sent: Monday, October 1, 2018 5:00 PM
> To: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Nikula, Jani <jani.nikula at intel.com>; intel-gfx at lists.freedesktop.org;
> Zanoni, Paulo R <paulo.r.zanoni at intel.com>
> Subject: Re: [Intel-gfx] [RFC 3/3] drm/i915/icl: Calculate DPLL params for DSI
> 
> 
> 
> > -----Original Message-----
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Sent: Wednesday, September 26, 2018 7:52 PM
> > To: Kulkarni, Vandita <vandita.kulkarni at intel.com>
> > Cc: intel-gfx at lists.freedesktop.org; Nikula, Jani
> > <jani.nikula at intel.com>; Zanoni, Paulo R <paulo.r.zanoni at intel.com>
> > Subject: Re: [Intel-gfx] [RFC 3/3] drm/i915/icl: Calculate DPLL params
> > for DSI
> >
> > On Thu, Sep 20, 2018 at 08:49:52AM +0000, Kulkarni, Vandita wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > Sent: Friday, September 14, 2018 9:39 PM
> > > > To: Kulkarni, Vandita <vandita.kulkarni at intel.com>
> > > > Cc: intel-gfx at lists.freedesktop.org; Nikula, Jani
> > > > <jani.nikula at intel.com>; Zanoni, Paulo R
> > > > <paulo.r.zanoni at intel.com>
> > > > Subject: Re: [Intel-gfx] [RFC 3/3] drm/i915/icl: Calculate DPLL
> > > > params for DSI
> > > >
> > > > On Fri, Sep 14, 2018 at 12:24:14PM +0530, Vandita Kulkarni wrote:
> > > > > From: Madhav Chauhan <madhav.chauhan at intel.com>
> > > > >
> > > > > This patch calculate various DPLL dividers and parameters for
> > > > > DSI encoder and adjust AFE clock for DSI. For DSI, 8x clock is AFE clock.
> > > > >
> > > > > v2: Extend haswell_crtc_compute_clock() for Gen11 DSI
> > > > > v3: Rebase
> > > > >
> > > > > Signed-off-by: Madhav Chauhan <madhav.chauhan at intel.com>
> > > > > Signed-off-by: Vandita Kulkarni <vandita.kulkarni at intel.com>
> > > > > ---
> > > > >  drivers/gpu/drm/i915/intel_display.c  | 4 +++-
> > > > > drivers/gpu/drm/i915/intel_dpll_mgr.c | 7 ++++++-
> > > > >  2 files changed, 9 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > > > > b/drivers/gpu/drm/i915/intel_display.c
> > > > > index 6928dcc..1a44c5e 100644
> > > > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > > > @@ -9238,10 +9238,12 @@ void hsw_disable_pc8(struct
> > > > > drm_i915_private
> > > > > *dev_priv)  static int haswell_crtc_compute_clock(struct intel_crtc
> *crtc,
> > > > >  				      struct intel_crtc_state *crtc_state)  {
> > > > > +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> > > > >  	struct intel_atomic_state *state =
> > > > >  		to_intel_atomic_state(crtc_state->base.state);
> > > > >
> > > > > -	if (!intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DSI)) {
> > > > > +	if (!intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DSI) ||
> > > > > +				 IS_ICELAKE(dev_priv)) {
> > > > >  		struct intel_encoder *encoder =
> > > > >  			intel_get_crtc_new_encoder(state, crtc_state);
> > > > >
> > > > > diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c
> > > > > b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> > > > > index 36ed155..5175e44 100644
> > > > > --- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
> > > > > +++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> > > > > @@ -22,6 +22,7 @@
> > > > >   */
> > > > >
> > > > >  #include "intel_drv.h"
> > > > > +#include "intel_dsi.h"
> > > > >
> > > > >  /**
> > > > >   * DOC: Display PLLs
> > > > > @@ -2532,7 +2533,11 @@ static bool icl_calc_dpll_state(struct
> > > > intel_crtc_state *crtc_state,
> > > > >  		ret = icl_calc_tbt_pll(dev_priv, clock, &pll_params);
> > > > >  	else if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
> > > > >  		ret = cnl_ddi_calculate_wrpll(clock, dev_priv, &pll_params);
> > > > > -	else
> > > > > +	else if (encoder->type == INTEL_OUTPUT_DSI) {
> > > > > +		struct intel_dsi *intel_dsi =
> enc_to_intel_dsi(&encoder->base);
> > > > > +		ret = cnl_ddi_calculate_wrpll(intel_dsi-
> >bitrate_khz/5,
> > > >
> > > > Missing port_clock=whatever in compute config?
> > > As per the spec I see that for mipi dsi on icl, 8x clock = AFE clock.
> > > And 8x clock is calculated and stored already as pixel_clk * bpp /
> > > lane_count Hence we are using already calculate 8x clock variable
> > > here and divide by/5 because later in the function it gets
> > > multiplied by 5 for afe
> > clock.
> > >
> > > port_clock is assigned to pixel clock as I see.
> >
> > port_clock can basically be anything you want. It's really up to the
> > encoder to define it. For DP it's the freq (1.62ghz, 2.7ghz, etc.),
> > for HDMI it's the TMDS character rate, for SDVO it's the multiplied pixel
> clock, etc.
> >
> > I suppose that means that currently port_clock is the output from the
> > dpll in pretty much all cases. Sticking to that same rule will make
> > DSI look less special and thus easier to understand for everyone.
> 
> Thank you, I will assign this bitrate_khz  (dsi_clk) to port_clock.

Please make sure we are not breaking anything else by doing this as there will be assumption
In DSI code that this is the pixelclk.
And still you need to divide it by 5 before passing to caller,
for DSI AFE clock  = 8X clock or Bitrate
which is different for HDMI where AFE Clock = symbol_clock_freq * 5.

Regards,
Madhav

> 
> Regards,
> Vandita
> >
> > > Please let me know if we have to use math around the port clock and
> > > pass that
> > value, than passing 8x clock.
> > >
> > > Thanks,
> > > Vandita
> > > >
> > > > > +					      dev_priv, &pll_params);
> > > > > +	} else
> > > > >  		ret = icl_calc_dp_combo_pll(dev_priv, clock, &pll_params);
> > > > >
> > > > >  	if (!ret)
> > > > > --
> > > > > 1.9.1
> > > > >
> > > > > _______________________________________________
> > > > > Intel-gfx mailing list
> > > > > Intel-gfx at lists.freedesktop.org
> > > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > > >
> > > > --
> > > > Ville Syrjälä
> > > > Intel
> >
> > --
> > Ville Syrjälä
> > Intel
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx