[PATCH v16 9/9] drm/i915: Compute CMRR and calculate vtotal

[Golani, Mitulkumar Ajitkumar]

Hi @Nathan Chancellor

Probably fix is merged in drm-intel-next
related patch:  https://patchwork.freedesktop.org/series/134860/

Can you please check and suggest if this patch is merged ?

Thanks,
Mitul
> -----Original Message-----
> From: Nathan Chancellor <nathan at kernel.org>
> Sent: Wednesday, June 19, 2024 9:12 PM
> To: Golani, Mitulkumar Ajitkumar <mitulkumar.ajitkumar.golani at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; Nautiyal, Ankit K
> <ankit.k.nautiyal at intel.com>; intel-xe at lists.freedesktop.org
> Subject: Re: [PATCH v16 9/9] drm/i915: Compute CMRR and calculate vtotal
> 
> Hi Mitul,
> 
> On Mon, Jun 10, 2024 at 12:52:02PM +0530, Mitul Golani wrote:
> ...
> > diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c
> > b/drivers/gpu/drm/i915/display/intel_vrr.c
> > index 4ad99a54aa83..05f67dc9d98d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> > @@ -12,6 +12,9 @@
> >  #include "intel_vrr_regs.h"
> >  #include "intel_dp.h"
> >
> > +#define FIXED_POINT_PRECISION		100
> > +#define CMRR_PRECISION_TOLERANCE	10
> > +
> >  bool intel_vrr_is_capable(struct intel_connector *connector)  {
> >  	const struct drm_display_info *info = &connector->base.display_info;
> > @@ -107,6 +110,52 @@ int intel_vrr_vmax_vblank_start(const struct
> intel_crtc_state *crtc_state)
> >  	return crtc_state->vrr.vmax -
> > intel_vrr_vblank_exit_length(crtc_state);
> >  }
> >
> > +static bool
> > +is_cmrr_frac_required(struct intel_crtc_state *crtc_state) {
> > +	int calculated_refresh_k, actual_refresh_k, pixel_clock_per_line;
> > +	struct drm_display_mode *adjusted_mode = &crtc_state-
> >hw.adjusted_mode;
> > +	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
> > +
> > +	if (!HAS_CMRR(i915))
> > +		return false;
> > +
> > +	actual_refresh_k =
> > +		drm_mode_vrefresh(adjusted_mode) *
> FIXED_POINT_PRECISION;
> > +	pixel_clock_per_line =
> > +		adjusted_mode->crtc_clock * 1000 / adjusted_mode-
> >crtc_htotal;
> > +	calculated_refresh_k =
> > +		pixel_clock_per_line * FIXED_POINT_PRECISION /
> > +adjusted_mode->crtc_vtotal;
> > +
> > +	if ((actual_refresh_k - calculated_refresh_k) <
> CMRR_PRECISION_TOLERANCE)
> > +		return false;
> > +
> > +	return true;
> > +}
> > +
> > +static unsigned int
> > +cmrr_get_vtotal(struct intel_crtc_state *crtc_state, bool
> > +video_mode_required) {
> > +	int multiplier_m = 1, multiplier_n = 1, vtotal, desired_refresh_rate;
> > +	long long adjusted_pixel_rate;
> > +	struct drm_display_mode *adjusted_mode =
> > +&crtc_state->hw.adjusted_mode;
> > +
> > +	desired_refresh_rate = drm_mode_vrefresh(adjusted_mode);
> > +
> > +	if (video_mode_required) {
> > +		multiplier_m = 1001;
> > +		multiplier_n = 1000;
> > +	}
> > +
> > +	crtc_state->cmrr.cmrr_n =
> > +		desired_refresh_rate * adjusted_mode->crtc_htotal *
> multiplier_n;
> > +	vtotal = (adjusted_mode->crtc_clock * 1000 * multiplier_n) /
> crtc_state->cmrr.cmrr_n;
> > +	adjusted_pixel_rate = adjusted_mode->crtc_clock * 1000 *
> multiplier_m;
> > +	crtc_state->cmrr.cmrr_m = do_div(adjusted_pixel_rate,
> > +crtc_state->cmrr.cmrr_n);
> > +
> > +	return vtotal;
> > +}
> 
> This change is now in -next as commit 1676ecd303ac ("drm/i915: Compute
> CMRR and calculate vtotal"), where it breaks the xe build for 32-bit platforms
> with:
> 
>   $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-
> allmodconfig drivers/gpu/drm/xe/i915-display/intel_vrr.o
>   In file included from arch/arm/include/asm/div64.h:107,
>                    from include/linux/math.h:6,
>                    from include/linux/kernel.h:27,
>                    from include/linux/cpumask.h:11,
>                    from include/linux/smp.h:13,
>                    from include/linux/lockdep.h:14,
>                    from include/linux/spinlock.h:63,
>                    from include/linux/kref.h:16,
>                    from include/drm/drm_device.h:5,
>                    from include/drm/drm_drv.h:35,
>                    from drivers/gpu/drm/xe/compat-i915-headers/i915_drv.h:13,
>                    from drivers/gpu/drm/i915/display/intel_vrr.c:7:
>   drivers/gpu/drm/i915/display/intel_vrr.c: In function 'cmrr_get_vtotal':
>   include/asm-generic/div64.h:222:35: error: comparison of distinct pointer
> types lacks a cast [-Werror]
>     222 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
>         |                                   ^~
>   drivers/gpu/drm/i915/display/intel_vrr.c:155:35: note: in expansion of macro
> 'do_div'
>     155 |         crtc_state->cmrr.cmrr_m = do_div(adjusted_pixel_rate, crtc_state-
> >cmrr.cmrr_n);
>         |                                   ^~~~~~
>   cc1: all warnings being treated as errors
> 
> Also, is do_div() correct here? It is different from the other div_() macros in that
> the "return value" is the remainder, not the result of the division.
> 
> Cheers,
> Nathan