Commit c3331d2f authored Feb 19, 2020 by Dmitry Osipenko Committed by David S. Miller Feb 19, 2020

nfc: pn544: Fix occasional HW initialization failure



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
device.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent a7a9456e

drivers/nfc/pn544/i2c.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -225,6 +225,7 @@ static void pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy)

		out:
		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)

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