I was regularly getting I/O errors when using the Renesas RSPI/QSPI
driver on r8a7791:
m25p80 spi0.0: error -110 reading SR
Until I applied the following patch, which re-reads RSPI_SPSR on a time-out,
and continues if the condition has become true:
diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index 4b31d89e8568..e63e30c500da 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -442,8 +442,13 @@ static int rspi_wait_for_interrupt(struct rspi_data *rspi,
u8 wait_mask,
rspi->spsr = rspi_read8(rspi, RSPI_SPSR);
rspi_enable_irq(rspi, enable_bit);
ret = wait_event_timeout(rspi->wait, rspi->spsr & wait_mask, HZ);
- if (ret == 0 && !(rspi->spsr & wait_mask))
- return -ETIMEDOUT;
+ if (ret == 0 && !(rspi->spsr & wait_mask)) {
+ u8 spsr = rspi_read8(rspi, RSPI_SPSR);
+ printk("*** rspi->spsr = 0x%02x, real spsr = 0x%02x, wait_mask
= 0x%02x ***\n",
+ rspi->spsr, spsr, wait_mask);
+ if (!(spsr & wait_mask))
+ return -ETIMEDOUT;
+ }
return 0;
}
Now it prints from time to time:
*** rspi->spsr = 0x20, real spsr = 0xa0, wait_mask = 0x80 ***
which shows that rspi->spsr (as set from the interrupt handler) didn't
have bit 7 set, while RSPI_SPSR does have bit 7 set.
So this looks like a race condition in the interrupt handling.
I didn't notice any data corruption after the patch.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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