linux-kernel - [PATCH v2 4/7] drm/vc4: hdmi: Fix hdmi_enable

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Message-Id: <20220815-rpi-fix-4k-60-v2-4-983276b83f62@cerno.tech>
Date:   Tue, 20 Sep 2022 14:50:23 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Daniel Vetter <daniel@...ll.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Michael Turquette <mturquette@...libre.com>,
        Scott Branden <sbranden@...adcom.com>,
        Stephen Boyd <sboyd@...nel.org>, Emma Anholt <emma@...olt.net>,
        Ray Jui <rjui@...adcom.com>, Maxime Ripard <mripard@...nel.org>
Cc:     linux-rpi-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, Dom Cobley <popcornmix@...il.com>,
        dri-devel@...ts.freedesktop.org, Maxime Ripard <maxime@...no.tech>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2 4/7] drm/vc4: hdmi: Fix hdmi_enable_4kp60 detection

In order to support higher HDMI frequencies, users have to set the
hdmi_enable_4kp60 parameter in their config.txt file.

We were detecting this so far by calling clk_round_rate() on the core
clock with the frequency we're supposed to run at when one of those
modes is enabled. Whether or not the parameter was enabled could then be
inferred by the returned rate since the maximum clock rate reported by
the firmware was one of the side effect of setting that parameter.

However, the recent clock rework we did changed what clk_round_rate()
was returning to always return the minimum allowed, and thus this test
wasn't reliable anymore.

Let's use the new clk_get_max_rate() function to reliably determine the
maximum rate allowed on that clock and fix the 4k@...z output.

Fixes: e9d6cea2af1c ("clk: bcm: rpi: Run some clocks at the minimum rate allowed")
Signed-off-by: Maxime Ripard <maxime@...no.tech>

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 1e5f68704d7d..3b75ac6fa0db 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -46,6 +46,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/rational.h>
 #include <linux/reset.h>
+#include <soc/bcm2835/raspberrypi-clocks.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/hdmi-codec.h>
 #include <sound/pcm_drm_eld.h>
@@ -2966,7 +2967,7 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 
 	if (variant->max_pixel_clock == 600000000) {
 		struct vc4_dev *vc4 = to_vc4_dev(drm);
-		long max_rate = clk_round_rate(vc4->hvs->core_clk, 550000000);
+		unsigned long max_rate = rpi_firmware_clk_get_max_rate(vc4->hvs->core_clk);
 
 		if (max_rate < 550000000)
 			vc4_hdmi->disable_4kp60 = true;

-- 
b4 0.10.0