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From: Johnny Liu <johnliu@nvidia.com>
To: Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Thierry Reding <thierry.reding@kernel.org>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	"Prashant Gaikwad" <pgaikwad@nvidia.com>,
	Stephen Boyd <sboyd@kernel.org>,
	Brian Masney <bmasney+clk@redhat.com>,
	Jerome Brunet <jbrunet+clk@baylibre.com>,
	"Douglas Anderson" <dianders@chromium.org>,
	Aniruddha Rao <anrao@nvidia.com>, <devicetree@vger.kernel.org>,
	<linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-clk@vger.kernel.org>
Cc: Johnny Liu <johnliu@nvidia.com>
Subject: [PATCH v2 4/4] clk: tegra: bpmp: Do not cache the EMC clock rate
Date: Wed, 28 Oct 2026 15:50:00 +0000	[thread overview]
Message-ID: <20261028155000.1205739-5-johnliu@nvidia.com> (raw)
In-Reply-To: <20261028155000.1205739-1-johnliu@nvidia.com>

EMC clock scaling is managed by the BPMP itself without kernel
involvement. When the rate changes on the BPMP side, clk_get_rate() on
the kernel side returns the stale value cached by the common clock
framework instead of the rate programmed by the BPMP.

Set CLK_GET_RATE_NOCACHE on the EMC clock, identified by the per-SoC
emc_clk_id from the BPMP SoC data, so that rate queries are forwarded to
the BPMP.

Signed-off-by: Johnny Liu <johnliu@nvidia.com>
---
 drivers/clk/tegra/clk-bpmp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/clk/tegra/clk-bpmp.c b/drivers/clk/tegra/clk-bpmp.c
index 067a8555c4e7..ddbc528cf93a 100644
--- a/drivers/clk/tegra/clk-bpmp.c
+++ b/drivers/clk/tegra/clk-bpmp.c
@@ -588,6 +588,9 @@ tegra_bpmp_clk_register(struct tegra_bpmp *bpmp,
 
 	init.parent_names = parents;
 
+	if (bpmp->soc->emc_clk_id && info->id == bpmp->soc->emc_clk_id)
+		init.flags = CLK_GET_RATE_NOCACHE;
+
 	err = devm_clk_hw_register(bpmp->dev, &clk->hw);
 
 	kfree(parents);
-- 
2.43.0


      parent reply	other threads:[~2026-10-28 16:06 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-28 15:49 [PATCH v2 0/4] Add Tegra238 BPMP support and fix stale " Johnny Liu
2026-10-28 15:49 ` [PATCH v2 1/4] dt-bindings: firmware: tegra186-bpmp: Add Tegra238 BPMP Johnny Liu
2026-10-28 15:49 ` [PATCH v2 2/4] firmware: tegra: bpmp: Add Tegra238 support Johnny Liu
2026-10-28 15:49 ` [PATCH v2 3/4] firmware: tegra: bpmp: Add per-SoC EMC clock ID Johnny Liu
2026-10-28 15:50 ` Johnny Liu [this message]

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