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From: Frank Oltmanns <frank@oltmanns.dev>
Date: Mon, 05 Feb 2024 16:22:29 +0100
Subject: [PATCH v2 6/6] arm64: dts: allwinner: a64: Fix minimum GPU OPP
 rate
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Message-Id: <20240205-pinephone-pll-fixes-v2-6-96a46a2d8c9b@oltmanns.dev>
References: <20240205-pinephone-pll-fixes-v2-0-96a46a2d8c9b@oltmanns.dev>
In-Reply-To: <20240205-pinephone-pll-fixes-v2-0-96a46a2d8c9b@oltmanns.dev>
To: Michael Turquette <mturquette@baylibre.com>, 
 Stephen Boyd <sboyd@kernel.org>, Chen-Yu Tsai <wens@csie.org>, 
 Jernej Skrabec <jernej.skrabec@gmail.com>, 
 Samuel Holland <samuel@sholland.org>, 
 =?utf-8?q?Guido_G=C3=BCnther?= <agx@sigxcpu.org>, 
 Purism Kernel Team <kernel@puri.sm>, Ondrej Jirman <megi@xff.cz>, 
 Neil Armstrong <neil.armstrong@linaro.org>, 
 Jessica Zhang <quic_jesszhan@quicinc.com>, Sam Ravnborg <sam@ravnborg.org>, 
 Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, 
 Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>, 
 David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
 Rob Herring <robh+dt@kernel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, 
 Conor Dooley <conor+dt@kernel.org>
Cc: linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, 
 linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, 
 dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, 
 Frank Oltmanns <frank@oltmanns.dev>

The PLL-GPU has a minimum rate of 192 MHz according to the A64 manual.

If run at less than 192 MHz the pinephone (based on the A64) sometimes
replays the last few frames that were displayed over and over (see first
link below).

Note, that running PLL-GPU at 240 MHz and using a divisor of 2 *should*
circumvent this problem as well. But unfortunately, the GPU shows the
erratic behaviour even more often, even though its parent is driven at a
supported range. This might be due to a similar issue to the one
observed on the Allwinner H6 (see second link).

Running both the GPU and PLL-GPU at more then 192 MHz reduces the
occurrenc of the issue.

Therefore, increase the minimum rate in the GPU OPP table to 192 MHz.

Link: https://gitlab.com/postmarketOS/pmaports/-/issues/805
Link: https://lore.kernel.org/linux-arm-kernel/2562485.k3LOHGUjKi@kista/T/
Signed-off-by: Frank Oltmanns <frank@oltmanns.dev>
---
 arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
index 57ac18738c99..448d7fbdd1a9 100644
--- a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
+++ b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
@@ -107,8 +107,8 @@ de: display-engine {
 	gpu_opp_table: opp-table-gpu {
 		compatible = "operating-points-v2";
 
-		opp-120000000 {
-			opp-hz = /bits/ 64 <120000000>;
+		opp-192000000 {
+			opp-hz = /bits/ 64 <192000000>;
 		};
 
 		opp-312000000 {

-- 
2.43.0