linux-kernel - [PATCH] arm64: dts: qcom: sc7180: Mark SCM as dma-coherent for trogdor

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Message-ID: <20230615145253.1.Ic62daa649b47b656b313551d646c4de9a7da4bd4@changeid>
Date:   Thu, 15 Jun 2023 14:52:54 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     andersson@...nel.org
Cc:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        konrad.dybcio@...ainline.org, sumit.semwal@...aro.org,
        Will Deacon <will@...nel.org>, amit.pundir@...aro.org,
        Sibi Sankar <quic_sibis@...cinc.com>,
        linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
        linux-arm-kernel@...ts.infradead.org,
        Douglas Anderson <dianders@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Clark <robdclark@...omium.org>,
        Rob Herring <robh+dt@...nel.org>,
        cros-qcom-dts-watchers@...omium.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] arm64: dts: qcom: sc7180: Mark SCM as dma-coherent for trogdor

Trogdor devices use firmware backed by TF-A instead of Qualcomm's
normal TZ. On TF-A we end up mapping memory as cachable. Specifically,
you can see in Trogdor's TF-A code [1] in qti_sip_mem_assign() that we
call qti_mmap_add_dynamic_region() with MT_RO_DATA. This translates
down to MT_MEMORY instead of MT_NON_CACHEABLE or MT_DEVICE. Apparently
Qualcomm's normal TZ implementation maps the memory as non-cachable.

Let's add the "dma-coherent" attribute to the SCM for trogdor.

Adding "dma-coherent" like this fixes WiFi on sc7180-trogdor
devices. WiFi was broken as of commit 7bd6680b47fa ("Revert "Revert
"arm64: dma: Drop cache invalidation from
arch_dma_prep_coherent()"""). Specifically at bootup we'd get:

 qcom_scm firmware:scm: Assign memory protection call failed -22
 qcom_rmtfs_mem 94600000.memory: assign memory failed
 qcom_rmtfs_mem: probe of 94600000.memory failed with error -22

>From discussion on the mailing lists [2] and over IRC [3], it was
determined that we should always have been tagging the SCM as
dma-coherent on trogdor but that the old "invalidate" happened to make
things work most of the time. Tagging it properly like this is a much
more robust solution.

[1] https://chromium.googlesource.com/chromiumos/third_party/arm-trusted-firmware/+/refs/heads/firmware-trogdor-13577.B/plat/qti/common/src/qti_syscall.c
[2] https://lore.kernel.org/r/20230614165904.1.I279773c37e2c1ed8fbb622ca6d1397aea0023526@changeid
[3] https://oftc.irclog.whitequark.org/linux-msm/2023-06-15

Fixes: 7bd6680b47fa ("Revert "Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()""")
Fixes: 7ec3e67307f8 ("arm64: dts: qcom: sc7180-trogdor: add initial trogdor and lazor dt")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 4 ++++
 arch/arm64/boot/dts/qcom/sc7180.dtsi         | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
index ca6920de7ea8..5e1e7c5bd474 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
@@ -1194,6 +1194,10 @@ &pm6150l_gpios {
 			  "";
 };
 
+&scm {
+	dma-coherent;
+};
+
 &tlmm {
 	/*
 	 * pinctrl settings for pins that have no real owners.
diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi
index f479cab8ab45..a65be760d1a7 100644
--- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
@@ -369,7 +369,7 @@ CLUSTER_SLEEP_0: cluster-sleep-0 {
 	};
 
 	firmware {
-		scm {
+		scm: scm {
 			compatible = "qcom,scm-sc7180", "qcom,scm";
 		};
 	};
-- 
2.41.0.162.gfafddb0af9-goog