| Message ID | 20200219150122.31524-1-digetx@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v1] nfc: pn544: Fix occasional HW initialization failure | expand |
From: Dmitry Osipenko <digetx@gmail.com> Date: Wed, 19 Feb 2020 18:01:22 +0300 > 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> Applied and queued up for -stable, thanks.
19.02.2020 22:11, David Miller пишет: > From: Dmitry Osipenko <digetx@gmail.com> > Date: Wed, 19 Feb 2020 18:01:22 +0300 > >> 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> > > Applied and queued up for -stable, thanks. > Awesome, thanks!
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) 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)
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. Cc: <stable@vger.kernel.org> Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- drivers/nfc/pn544/i2c.c | 1 + 1 file changed, 1 insertion(+)