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can: m_can: m_can_fifo_{read,write}: don't read or write from/to FIFO if length is 0

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In order to optimize FIFO access, especially on m_can cores attached
to slow busses like SPI, in patch

| e39381770e ("can: m_can: Disable IRQs on FIFO bus errors")

bulk read/write support has been added to the m_can_fifo_{read,write}
functions.

That change leads to the tcan driver to call
regmap_bulk_{read,write}() with a length of 0 (for CAN frames with 0
data length). regmap treats this as an error:

| tcan4x5x spi1.0 tcan4x5x0: FIFO write returned -22

This patch fixes the problem by not calling the
cdev->ops->{read,write)_fifo() in case of a 0 length read/write.

Fixes: e39381770e ("can: m_can: Disable IRQs on FIFO bus errors")
Link: https://lore.kernel.org/all/20220114155751.2651888-1-mkl@pengutronix.de
Cc: stable@vger.kernel.org
Cc: Matt Kline <matt@bitbashing.io>
Cc: Chandrasekar Ramakrishnan <rcsekar@samsung.com>
Reported-by: Michael Anochin <anochin@photo-meter.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Marc Kleine-Budde 2022-01-14 15:35:01 +01:00
parent 17a3042262
commit db72589c49
1 changed files with 6 additions and 0 deletions
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6
drivers/net/can/m_can/m_can.c
View File

@ -336,6 +336,9 @@ m_can_fifo_read(struct m_can_classdev *cdev,
u32 addr_offset = cdev->mcfg[MRAM_RXF0].off + fgi * RXF0_ELEMENT_SIZE +
offset;
if (val_count == 0)
return 0;
return cdev->ops->read_fifo(cdev, addr_offset, val, val_count);
}
@ -346,6 +349,9 @@ m_can_fifo_write(struct m_can_classdev *cdev,
u32 addr_offset = cdev->mcfg[MRAM_TXB].off + fpi * TXB_ELEMENT_SIZE +
offset;
if (val_count == 0)
return 0;
return cdev->ops->write_fifo(cdev, addr_offset, val, val_count);
}