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Sun, 25 Oct 2026 12:36:21 -0700 (PDT) Received: from cachyos-aura ([45.112.149.26]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-198a0f81ea9sm21412877c88.11.2026.10.25.12.36.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Oct 2026 12:36:20 -0700 (PDT) From: Navon John Lukose To: Andy Shevchenko , Lee Jones Cc: Mika Westerberg , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , mfd@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v3] mfd: intel-lpss: Set d3hot_delay to 0 Date: Mon, 26 Oct 2026 01:06:13 +0530 Message-ID: <20261025193613.278610-1-navonjohnlukose@gmail.com> X-Mailer: git-send-email 2.56.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Every runtime resume of an LPSS controller waits the default 10 ms d3hot_delay in pci_power_up() for the D3hot->D0 transition. Nothing misbehaves, but the wait adds latency. On Arrow Lake-H (Lenovo Yoga Pro 7 14IAH10) the touchpad's I2C controller autosuspends after 1 s idle, and the i2c-hid interrupt handler for the first report afterwards takes 12.6-14.4 ms. The PCI spec asks for those 10 ms, but Mika Westerberg pointed out that the LPSS controllers are not really PCI-connected devices, so the delay is likely not needed. intel-lpss-pci already clears d3cold_delay, quirk_remove_d3hot_delay() drops d3hot_delay on several older Intel chipsets, Cherry Trail among them, and commit 815b4448198f ("i3c: mipi-i3c-hci-pci: Set d3hot_delay to 0 for Intel controllers") does the same for the Intel I3C controllers. Set d3hot_delay to 0 as well. The handler above then takes 1.1-1.9 ms, with no I2C errors. Only Arrow Lake-H was tested. Acked-by: Mika Westerberg Signed-off-by: Navon John Lukose --- Notes: Changes in v3: - Describe the delay first, then why it is not needed (Ilpo). - Give Mika's full name (Ilpo). - Add Mika's Acked-by. Changes in v2: - Drop RFC and add the review discussion to the changelog (Andy). v2: https://lore.kernel.org/r/20261022040453.45797-1-navonjohnlukose@gmail.com RFC: https://lore.kernel.org/r/20261016114347.23633-1-navonjohnlukose@gmail.com drivers/mfd/intel-lpss-pci.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/mfd/intel-lpss-pci.c b/drivers/mfd/intel-lpss-pci.c index 63a3fb58566..5672f033e5c 100644 --- a/drivers/mfd/intel-lpss-pci.c +++ b/drivers/mfd/intel-lpss-pci.c @@ -70,6 +70,7 @@ static int intel_lpss_pci_probe(struct pci_dev *pdev, info->quirks = quirk_pci_info->driver_data; pdev->d3cold_delay = 0; + pdev->d3hot_delay = 0; /* Probably it is enough to set this for iDMA capable devices only */ pci_set_master(pdev); -- 2.56.0