linux-kernel - [PATCH AUTOSEL 4.4 2/9] mfd: intel-lpss: Remove D3cold delay

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Date:   Sun, 29 Sep 2019 13:36:47 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Lee Jones <lee.jones@...aro.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.4 2/9] mfd: intel-lpss: Remove D3cold delay

From: Kai-Heng Feng <kai.heng.feng@...onical.com>

[ Upstream commit 76380a607ba0b28627c9b4b55cd47a079a59624b ]

Goodix touchpad may drop its first couple input events when
i2c-designware-platdrv and intel-lpss it connects to took too long to
runtime resume from runtime suspended state.

This issue happens becuase the touchpad has a rather small buffer to
store up to 13 input events, so if the host doesn't read those events in
time (i.e. runtime resume takes too long), events are dropped from the
touchpad's buffer.

The bottleneck is D3cold delay it waits when transitioning from D3cold
to D0, hence remove the delay to make the resume faster. I've tested
some systems with intel-lpss and haven't seen any regression.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202683
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/mfd/intel-lpss-pci.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/mfd/intel-lpss-pci.c b/drivers/mfd/intel-lpss-pci.c
index 5bfdfccbb9a1a..032c95157497f 100644
--- a/drivers/mfd/intel-lpss-pci.c
+++ b/drivers/mfd/intel-lpss-pci.c
@@ -38,6 +38,8 @@ static int intel_lpss_pci_probe(struct pci_dev *pdev,
 	info->mem = &pdev->resource[0];
 	info->irq = pdev->irq;

+	pdev->d3cold_delay = 0;
+
 	/* Probably it is enough to set this for iDMA capable devices only */
 	pci_set_master(pdev);

-- 
2.20.1