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Date: Fri, 27 Apr 2018 12:59:50 +0000 From: Philippe CORNU <philippe.cornu@...com> To: Yannick FERTRE <yannick.fertre@...com>, Benjamin Gaignard <benjamin.gaignard@...aro.org>, Vincent ABRIOU <vincent.abriou@...com>, "David Airlie" <airlied@...ux.ie>, "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> CC: Alexandre TORGUE <alexandre.torgue@...com> Subject: Re: [PATCH] drm/stm: ltdc: add mode_valid() On 04/25/2018 09:12 AM, Yannick FERTRE wrote: > Hi Philippe, > > Reviewed-by: Yannick Fertré <yannick.fertre@...com> > Applied on drm-misc-next. Many thanks, Philippe :-) > On 04/17/2018 01:40 PM, Philippe Cornu wrote: >> Add mode_valid() function to filter modes according to available >> pll clock values and "preferred" modes. It is particularly >> useful for hdmi modes that require precise pixel clocks. >> >> Note that "preferred" modes are always accepted: >> - this is important for panels because panel clock tolerances are >> bigger than hdmi ones and there is no reason to not accept them >> (the fps may vary a little but it is not a problem). >> - the hdmi preferred mode will be accepted too, but userland will >> be able to use others hdmi "valid" modes if necessary. >> >> Signed-off-by: Philippe Cornu <philippe.cornu@...com> >> --- >> drivers/gpu/drm/stm/ltdc.c | 38 ++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 38 insertions(+) >> >> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c >> index 014cef8cef37..616191fe98ae 100644 >> --- a/drivers/gpu/drm/stm/ltdc.c >> +++ b/drivers/gpu/drm/stm/ltdc.c >> @@ -445,6 +445,43 @@ static void ltdc_crtc_atomic_disable(struct drm_crtc *crtc, >> reg_set(ldev->regs, LTDC_SRCR, SRCR_IMR); >> } >> >> +#define CLK_TOLERANCE_HZ 50 >> + >> +static enum drm_mode_status >> +ltdc_crtc_mode_valid(struct drm_crtc *crtc, >> + const struct drm_display_mode *mode) >> +{ >> + struct ltdc_device *ldev = crtc_to_ltdc(crtc); >> + int target = mode->clock * 1000; >> + int target_min = target - CLK_TOLERANCE_HZ; >> + int target_max = target + CLK_TOLERANCE_HZ; >> + int result; >> + >> + /* >> + * Accept all "preferred" modes: >> + * - this is important for panels because panel clock tolerances are >> + * bigger than hdmi ones and there is no reason to not accept them >> + * (the fps may vary a little but it is not a problem). >> + * - the hdmi preferred mode will be accepted too, but userland will >> + * be able to use others hdmi "valid" modes if necessary. >> + */ >> + if (mode->type & DRM_MODE_TYPE_PREFERRED) >> + return MODE_OK; >> + >> + result = clk_round_rate(ldev->pixel_clk, target); >> + >> + DRM_DEBUG_DRIVER("clk rate target %d, available %d\n", target, result); >> + >> + /* >> + * Filter modes according to the clock value, particularly useful for >> + * hdmi modes that require precise pixel clocks. >> + */ >> + if (result < target_min || result > target_max) >> + return MODE_CLOCK_RANGE; >> + >> + return MODE_OK; >> +} >> + >> static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc, >> const struct drm_display_mode *mode, >> struct drm_display_mode *adjusted_mode) >> @@ -559,6 +596,7 @@ static void ltdc_crtc_atomic_flush(struct drm_crtc *crtc, >> } >> >> static const struct drm_crtc_helper_funcs ltdc_crtc_helper_funcs = { >> + .mode_valid = ltdc_crtc_mode_valid, >> .mode_fixup = ltdc_crtc_mode_fixup, >> .mode_set_nofb = ltdc_crtc_mode_set_nofb, >> .atomic_flush = ltdc_crtc_atomic_flush,
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