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From:   Mario Limonciello <mario.limonciello@amd.com>
To:     Hans de Goede <hdegoede@redhat.com>,
        Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
CC:     Mario Limonciello <mario.limonciello@amd.com>,
        "Mahapatra, Rajib" <Rajib.Mahapatra@amd.com>,
        Raul Rangel <rrangel@chromium.org>,
        Mark Gross <markgross@kernel.org>,
        <platform-driver-x86@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: [PATCH] platform/x86/amd: pmc: Add a workaround for an s0i3 issue on Cezanne
Date:   Wed, 16 Nov 2022 09:43:41 -0600
Message-ID: <20221116154341.13382-1-mario.limonciello@amd.com>
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Cezanne platforms under the right circumstances have a synchronization
problem where attempting to enter s2idle may fail if the x86 cores are
put into HLT before hardware resume from the previous attempt has
completed.

To avoid this issue add a 10-20ms delay before entering s2idle another
time. This workaround will only be applied on interrupts that wake the
hardware but don't break the s2idle loop.

Cc: "Mahapatra, Rajib" <Rajib.Mahapatra@amd.com>
Cc: "Raul Rangel" <rrangel@chromium.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/platform/x86/amd/pmc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/platform/x86/amd/pmc.c b/drivers/platform/x86/amd/pmc.c
index ef4ae977b8e0..439d282aafd1 100644
--- a/drivers/platform/x86/amd/pmc.c
+++ b/drivers/platform/x86/amd/pmc.c
@@ -739,8 +739,14 @@ static void amd_pmc_s2idle_prepare(void)
 static void amd_pmc_s2idle_check(void)
 {
 	struct amd_pmc_dev *pdev = &pmc;
+	struct smu_metrics table;
 	int rc;
 
+	/* CZN: Ensure that future s0i3 entry attempts at least 10ms passed */
+	if (pdev->cpu_id == AMD_CPU_ID_CZN && !get_metrics_table(pdev, &table) &&
+	    table.s0i3_last_entry_status)
+		usleep_range(10000, 20000);
+
 	/* Dump the IdleMask before we add to the STB */
 	amd_pmc_idlemask_read(pdev, pdev->dev, NULL);
 
-- 
2.34.1