blob: aa1b13333c2b955e3c45303ede2fc1659d0c040a [file] [log] [blame]
From 3ad75a70a79e63dbb7fcd6195683a2250fe262aa Mon Sep 17 00:00:00 2001
From: Dmitry Osipenko <>
Date: Wed, 19 Feb 2020 18:01:22 +0300
Subject: [PATCH] nfc: pn544: Fix occasional HW initialization failure
commit c3331d2fe3fd4d5e321f2467d01f72de7edfb5d0 upstream.
The PN544 driver checks the "enable" polarity during of driver's probe and
it's doing that by turning ON and OFF NFC with different polarities until
enabling succeeds. It takes some time for the hardware to power-down, and
thus, to deassert the IRQ that is raised by turning ON the hardware.
Since the delay after last power-down of the polarity-checking process is
missed in the code, the interrupt may trigger immediately after installing
the IRQ handler (right after the checking is done), which results in IRQ
handler trying to touch the disabled HW and ends with marking NFC as
'DEAD' during of the driver's probe:
pn544_hci_i2c 1-002a: NFC: nfc_en polarity : active high
pn544_hci_i2c 1-002a: NFC: invalid len byte
shdlc: llc_shdlc_recv_frame: NULL Frame -> link is dead
This patch fixes the occasional NFC initialization failure on Nexus 7
Signed-off-by: Dmitry Osipenko <>
Signed-off-by: David S. Miller <>
Signed-off-by: Paul Gortmaker <>
diff --git a/drivers/nfc/pn544/i2c.c b/drivers/nfc/pn544/i2c.c
index 720c89d6066e..4ac8cb262559 100644
--- a/drivers/nfc/pn544/i2c.c
+++ b/drivers/nfc/pn544/i2c.c
@@ -225,6 +225,7 @@ static void pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy)
gpiod_set_value_cansleep(phy->gpiod_en, !phy->en_polarity);
+ usleep_range(10000, 15000);
static void pn544_hci_i2c_enable_mode(struct pn544_i2c_phy *phy, int run_mode)