[ Upstream commit c3331d2fe3fd4d5e321f2467d01f72de7edfb5d0 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5080832627b65e3772a35d1dced68c64e2b24442 upstream.
Clang warns
../drivers/nfc/pn544/pn544.c:696:4: warning: misleading indentation;
statement is not part of the previous 'if' [-Wmisleading-indentation]
return nfc_hci_send_cmd(hdev, NFC_HCI_RF_READER_A_GATE,
^
../drivers/nfc/pn544/pn544.c:692:3: note: previous statement is here
if (target->nfcid1_len != 4 && target->nfcid1_len != 7 &&
^
1 warning generated.
This warning occurs because there is a space after the tab on this line.
Remove it so that the indentation is consistent with the Linux kernel
coding style and clang no longer warns.
Fixes: da052850b911 ("NFC: Add pn544 presence check for different targets")
Link: https://github.com/ClangBuiltLinux/linux/issues/814
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
