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NFC: trf7970a: Handle low-watermark IRQ when transmitting 

Commit 4dd836e46c ("NFC: trf7970a: Reset FIFO when
'End of TX' Interrupt Occurs") fixes the issue that
it was meant to fix but adds the unfortunate side
effect of causing the driver to report an error
when the TX low-watermark level is passed during
transmits.  This can be fixed by checking whether
the IRQ status indicates that the low-watermark
has been passed when transmitting.  If it has been
passed and the FIFO is empty, then its safe to reset
the FIFO.  Otherwise, silently continue since another
TX interrupt will be generated and the FIFO will be
reset then.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Mark A. Greer 2014-09-02 15:12:30 -07:00 committed by Samuel Ortiz
parent 0e840ed59b
commit bece3c544f
1 changed files with 11 additions and 1 deletions
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12
drivers/nfc/trf7970a.c
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@ -667,7 +667,7 @@ static irqreturn_t trf7970a_irq(int irq, void *dev_id)
{
struct trf7970a *trf = dev_id;
int ret;
u8 status;
u8 status, fifo_bytes;
mutex_lock(&trf->lock);
@ -720,6 +720,16 @@ static irqreturn_t trf7970a_irq(int irq, void *dev_id)
trf->ignore_timeout =
!cancel_delayed_work(&trf->timeout_work);
trf7970a_drain_fifo(trf, status);
} else if (status & TRF7970A_IRQ_STATUS_FIFO) {
ret = trf7970a_read(trf, TRF7970A_FIFO_STATUS,
&fifo_bytes);
fifo_bytes &= ~TRF7970A_FIFO_STATUS_OVERFLOW;
if (ret)
trf7970a_send_err_upstream(trf, ret);
else if (!fifo_bytes)
trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
} else if (status == TRF7970A_IRQ_STATUS_TX) {
trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
} else {