linux-kernel - [PATCH 07/13] soc: mediatek: mtk-dvfsrc: Write bandwidth to EMI DDR if present

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Message-Id: <20251114-mt8196-dvfsrc-v1-7-b956d4631468@collabora.com>
Date: Fri, 14 Nov 2025 17:54:01 +0100
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Henry Chen <henryc.chen@...iatek.com>, Georgi Djakov <djakov@...nel.org>
Cc: kernel@...labora.com, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-mediatek@...ts.infradead.org, linux-pm@...r.kernel.org, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH 07/13] soc: mediatek: mtk-dvfsrc: Write bandwidth to EMI
 DDR if present

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

In preparation for adding support for DVFSRC Version 4, add a new
`has_emi_ddr` member to struct dvfsrc_soc_data: if true, write the
DRAM bandwidth both to the BW_AVG and to the newly defined EMI_BW
register, present only on DVFSRC v4.

Currently supported SoCs will not use this, as has_emi_ddr is left
out from their platform data, hence reading false.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/soc/mediatek/mtk-dvfsrc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/soc/mediatek/mtk-dvfsrc.c b/drivers/soc/mediatek/mtk-dvfsrc.c
index 3cbccbb7469a..bf0e7b01d255 100644
--- a/drivers/soc/mediatek/mtk-dvfsrc.c
+++ b/drivers/soc/mediatek/mtk-dvfsrc.c
@@ -72,6 +72,7 @@ struct mtk_dvfsrc {
 
 struct dvfsrc_soc_data {
 	const int *regs;
+	const bool has_emi_ddr;
 	const struct dvfsrc_opp_desc *opps_desc;
 	u32 (*calc_dram_bw)(struct mtk_dvfsrc *dvfsrc, int type, u64 bw);
 	u32 (*get_target_level)(struct mtk_dvfsrc *dvfsrc);
@@ -107,6 +108,7 @@ enum dvfsrc_regs {
 	DVFSRC_SW_BW,
 	DVFSRC_SW_PEAK_BW,
 	DVFSRC_SW_HRT_BW,
+	DVFSRC_SW_EMI_BW,
 	DVFSRC_VCORE,
 	DVFSRC_REGS_MAX,
 };
@@ -292,6 +294,9 @@ static void __dvfsrc_set_dram_bw_v1(struct mtk_dvfsrc *dvfsrc, u32 reg,
 		new_bw = max(new_bw, min_bw);
 
 	dvfsrc_writel(dvfsrc, reg, new_bw);
+
+	if (type == DVFSRC_BW_AVG && dvfsrc->dvd->has_emi_ddr)
+		dvfsrc_writel(dvfsrc, DVFSRC_SW_EMI_BW, bw);
 }
 
 static void dvfsrc_set_dram_bw_v1(struct mtk_dvfsrc *dvfsrc, u64 bw)

-- 
2.51.2