From 6a00a4221a9af8117c5fc1d7e2740614bb7626f7 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Tue, 20 Jun 2017 22:35:44 +0300 Subject: [PATCH] drm: rcar-du: Restrict DPLL duty cycle workaround to H3 ES1.x The H3 ES1.x exhibits dot clock duty cycle stability issues. We can work around them by configuring the DPLL to twice the desired frequency, coupled with a /2 post-divider. This isn't needed on other SoCs and breaks HDMI output on M3-W for a currently unknown reason, so restrict the workaround to H3 ES1.x. From an implementation point of view, move work around handling outside of the rcar_du_dpll_divider() function by requesting a x2 DPLL output frequency explicitly. The existing post-divider calculation mechanism will then take care of dividing the clock by two automatically. While at it, print a more useful debugging message to ease debugging clock rate issues. Signed-off-by: Laurent Pinchart Reviewed-by: Kieran Bingham --- drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 37 +++++++++++++++++++------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c index 63c32b3582fb..d82aa67162c6 100644 --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c @@ -13,6 +13,7 @@ #include #include +#include #include #include @@ -129,10 +130,8 @@ static void rcar_du_dpll_divider(struct rcar_du_crtc *rcrtc, for (fdpll = 1; fdpll < 32; fdpll++) { unsigned long output; - /* 1/2 (FRQSEL=1) for duty rate 50% */ output = input * (n + 1) / (m + 1) - / (fdpll + 1) / 2; - + / (fdpll + 1); if (output >= 400000000) continue; @@ -158,6 +157,11 @@ done: best_diff); } +static const struct soc_device_attribute rcar_du_r8a7795_es1[] = { + { .soc_id = "r8a7795", .revision = "ES1.*" }, + { /* sentinel */ } +}; + static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc) { const struct drm_display_mode *mode = &rcrtc->crtc.state->adjusted_mode; @@ -186,7 +190,20 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc) extclk = clk_get_rate(rcrtc->extclock); if (rcdu->info->dpll_ch & (1 << rcrtc->index)) { - rcar_du_dpll_divider(rcrtc, &dpll, extclk, mode_clock); + unsigned long target = mode_clock; + + /* + * The H3 ES1.x exhibits dot clock duty cycle stability + * issues. We can work around them by configuring the + * DPLL to twice the desired frequency, coupled with a + * /2 post-divider. This isn't needed on other SoCs and + * breaks HDMI output on M3-W for a currently unknown + * reason, so restrict the workaround to H3 ES1.x. + */ + if (soc_device_match(rcar_du_r8a7795_es1)) + target *= 2; + + rcar_du_dpll_divider(rcrtc, &dpll, extclk, target); extclk = dpll.output; } @@ -198,8 +215,6 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc) if (abs((long)extrate - (long)mode_clock) < abs((long)rate - (long)mode_clock)) { - dev_dbg(rcrtc->group->dev->dev, - "crtc%u: using external clock\n", rcrtc->index); if (rcdu->info->dpll_ch & (1 << rcrtc->index)) { u32 dpllcr = DPLLCR_CODE | DPLLCR_CLKE @@ -216,12 +231,14 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc) rcar_du_group_write(rcrtc->group, DPLLCR, dpllcr); - - escr = ESCR_DCLKSEL_DCLKIN | 1; - } else { - escr = ESCR_DCLKSEL_DCLKIN | extdiv; } + + escr = ESCR_DCLKSEL_DCLKIN | extdiv; } + + dev_dbg(rcrtc->group->dev->dev, + "mode clock %lu extrate %lu rate %lu ESCR 0x%08x\n", + mode_clock, extrate, rate, escr); } rcar_du_group_write(rcrtc->group, rcrtc->index % 2 ? ESCR2 : ESCR, -- 2.20.1