On Thu, 20 Jun 2024, "Golani, Mitulkumar Ajitkumar" <mitulkumar.ajitkumar.golani@xxxxxxxxx> wrote: > Hi @Nathan Chancellor, > > Yes, with do_div, we are expecting the remainder value. Regarding the > warning related to the adjusted_pixel_rate type cast, I haven't been > able to reproduce this locally, possibly due to differences in the > cross-compiler. We should consider typecasting adjusted_pixel_rate or > treating it as unsigned ? Please avoid top-posting on the mailing lists. I'm guessing this will be enough. diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c index 6430da25957d..5a0da64c7db3 100644 --- a/drivers/gpu/drm/i915/display/intel_vrr.c +++ b/drivers/gpu/drm/i915/display/intel_vrr.c @@ -137,7 +137,7 @@ 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; + u64 adjusted_pixel_rate; struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode; desired_refresh_rate = drm_mode_vrefresh(adjusted_mode); BR, Jani. > > Adding @Nikula, Jani to suggest. > > Regards, > Mitul >> -----Original Message----- >> From: Nathan Chancellor <nathan@xxxxxxxxxx> >> Sent: Wednesday, June 19, 2024 11:56 PM >> To: Golani, Mitulkumar Ajitkumar <mitulkumar.ajitkumar.golani@xxxxxxxxx> >> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Nautiyal, Ankit K >> <ankit.k.nautiyal@xxxxxxxxx>; intel-xe@xxxxxxxxxxxxxxxxxxxxx >> Subject: Re: [PATCH v16 9/9] drm/i915: Compute CMRR and calculate vtotal >> >> On Wed, Jun 19, 2024 at 06:10:34PM +0000, Golani, Mitulkumar Ajitkumar >> wrote: >> > 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 ? >> >> This is still reproducible at commit 851de367dede ("drm/i915: Enable >> plane/pipeDMC ATS fault interrupts on mtl") in drm-intel-next, which includes >> that change as commit e2dc7cb72b25 ("drm/i915/display: Update calculation >> to avoid overflow"). The issue is the dividend in do_div() is required to be an >> unsigned 64-bit type but you used a signed type. >> Updating adjusted_pixel_rate to be a u64 should resolve the issue and match >> the return type of mul_u32_u32(). I just wasn't sure if that was the only fix >> this code would need, as do_div() is not typically used with an assignment. >> >> Cheers, >> Nathan >> >> > > -----Original Message----- >> > > From: Nathan Chancellor <nathan@xxxxxxxxxx> >> > > Sent: Wednesday, June 19, 2024 9:12 PM >> > > To: Golani, Mitulkumar Ajitkumar >> > > <mitulkumar.ajitkumar.golani@xxxxxxxxx> >> > > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Nautiyal, Ankit K >> > > <ankit.k.nautiyal@xxxxxxxxx>; intel-xe@xxxxxxxxxxxxxxxxxxxxx >> > > 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 -- Jani Nikula, Intel