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spi/fsl-espi: avoid infinite loops on fsl_espi_cpu_irq() 

It brought nearly infinite loops, and was possible to be
occurred only if the SPI transaction total size are not
alighed with 4. Loops are here at while (tmp--),
tmp is unsigned, and set it with minus value.

The loops are executed as a result of unexpected RX interrupt
occurrence after that. This interrupt may be hardware eratta
and is not fixed.

Fix mspi->len from minus value to 0 and print warning message.

Signed-off-by: Nobuteru Hayashi <hayashi.nbb@ncos.nec.co.jp>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Nobuteru Hayashi 2016-03-18 11:35:21 +00:00 committed by Mark Brown
parent aa70e567c4
commit 6319a68011
1 changed files with 9 additions and 1 deletions
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10
drivers/spi/spi-fsl-espi.c
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@ -544,6 +544,7 @@ void fsl_espi_cpu_irq(struct mpc8xxx_spi *mspi, u32 events)
if (events & SPIE_NE) {
u32 rx_data, tmp;
u8 rx_data_8;
int rx_nr_bytes = 4;
int ret;
/* Spin until RX is done */
@ -560,7 +561,14 @@ void fsl_espi_cpu_irq(struct mpc8xxx_spi *mspi, u32 events)
if (mspi->len >= 4) {
rx_data = mpc8xxx_spi_read_reg(&reg_base->receive);
} else if (mspi->len <= 0) {
dev_err(mspi->dev,
"unexpected RX(SPIE_NE) interrupt occurred,\n"
"(local rxlen %d bytes, reg rxlen %d bytes)\n",
min(4, mspi->len), SPIE_RXCNT(events));
rx_nr_bytes = 0;
} else {
rx_nr_bytes = mspi->len;
tmp = mspi->len;
rx_data = 0;
while (tmp--) {
@ -571,7 +579,7 @@ void fsl_espi_cpu_irq(struct mpc8xxx_spi *mspi, u32 events)
rx_data <<= (4 - mspi->len) * 8;
}
mspi->len -= 4;
mspi->len -= rx_nr_bytes;
if (mspi->rx)
mspi->get_rx(rx_data, mspi);