On Thu, Nov 05, 2020 at 05:39:31PM +0100, Marc Kleine-Budde wrote: > On 11/5/20 5:24 PM, Manivannan Sadhasivam wrote: > > Hi Marc, > > > > On Tue, Nov 03, 2020 at 11:06:30PM +0100, Marc Kleine-Budde wrote: > >> During debugging it turned out that some people have setups where the SPI > >> communication is more prone to CRC errors. > >> > >> Increase the severity of both the transfer retry and transfer failure message > >> to give users feedback without the need to recompile the driver with debug > >> enabled. > >> > >> Cc: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > >> Cc: Thomas Kopp <thomas.kopp@xxxxxxxxxxxxx> > >> Link: http://lore.kernel.org/r/20201019190524.1285319-15-mkl@xxxxxxxxxxxxxx > >> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> > >> --- > >> drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c | 16 ++++++++-------- > >> 1 file changed, 8 insertions(+), 8 deletions(-) > >> > >> diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c > >> index ba25902dd78c..c9ffc5ea2b25 100644 > >> --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c > >> +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c > >> @@ -330,17 +330,17 @@ mcp251xfd_regmap_crc_read(void *context, > >> goto out; > >> } > >> > >> - netdev_dbg(priv->ndev, > >> - "CRC read error at address 0x%04x (length=%zd, data=%*ph, CRC=0x%04x) retrying.\n", > >> - reg, val_len, (int)val_len, buf_rx->data, > >> - get_unaligned_be16(buf_rx->data + val_len)); > >> - } > >> - > >> - if (err) { > >> netdev_info(priv->ndev, > >> - "CRC read error at address 0x%04x (length=%zd, data=%*ph, CRC=0x%04x).\n", > >> + "CRC read error at address 0x%04x (length=%zd, data=%*ph, CRC=0x%04x) retrying.\n", > >> reg, val_len, (int)val_len, buf_rx->data, > >> get_unaligned_be16(buf_rx->data + val_len)); > > > > I'm not finding this inner debug log useful. Does the user really care > > about the iterations it took to read a register? Just throwing the error > > after max try seems better to me. > > Bitflips on the SPI should not happen, at least not regularly. Even with my > breadboard setup and max SPI frequency, I don't see any SPI CRC errors, unless > there is bad cabling. Then a retry most of the times helps and the user doesn't > notice. This drops performance...Yes logging drop performance, too, but at least > someone will notice. > > My rationale was to give the user feedback and not cover a potential problem. > The driver is new and probably not widely used and I have no idea how often it > runs into read-CRC problems in production use. > Okay. Let's see if anyone complain ;) Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> Thanks, Mani > Marc > > -- > Pengutronix e.K. | Marc Kleine-Budde | > Embedded Linux | https://www.pengutronix.de | > Vertretung West/Dortmund | Phone: +49-231-2826-924 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | >
