From mboxrd@z Thu Jan 1 00:00:00 1970 From: mkl@pengutronix.de (Marc Kleine-Budde) Date: Wed, 05 Nov 2014 11:17:48 +0100 Subject: [PATCH V2 2/4] can: m_can: workaround for transmit data less than 4 bytes In-Reply-To: <1415174326-6623-2-git-send-email-b29396@freescale.com> References: <1415174326-6623-1-git-send-email-b29396@freescale.com> <1415174326-6623-2-git-send-email-b29396@freescale.com> Message-ID: <5459F94C.1030506@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11/05/2014 08:58 AM, Dong Aisheng wrote: > At least on the i.MX6SX with M_CAN IP version 3.0.x, an issue with Can you add the imx mask revision, too and the exact m_can version (is available). > the Message RAM was discovered. Sending CAN frames with dlc less > than 4 bytes will lead to bit errors, when the first 8 bytes of > the Message RAM have not been initialized (i.e. written to). > To work around this issue, the first 8 bytes are initialized in open() > function. > > Without the workaround, we can easily see the following errors: > root at imx6qdlsolo:~# ip link set can0 up type can bitrate 1000000 > [ 66.882520] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready > root at imx6qdlsolo:~# cansend can0 123#112233 > [ 66.935640] m_can 20e8000.can can0: Bit Error Uncorrected > > Signed-off-by: Dong Aisheng > --- > ChangeLog since v1: > * initialize the first 8 bytes of Tx Buffer of Message RAM in open() > to workaround the issue > --- > drivers/net/can/m_can/m_can.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c > index 664fe30..f47c200 100644 > --- a/drivers/net/can/m_can/m_can.c > +++ b/drivers/net/can/m_can/m_can.c > @@ -902,6 +902,15 @@ static void m_can_chip_config(struct net_device *dev) > /* set bittiming params */ > m_can_set_bittiming(dev); > > + /* At least on the i.MX6SX with M_CAN IP version 3.0.x, an issue with > + * the Message RAM was discovered. Sending CAN frames with dlc less > + * than 4 bytes will lead to bit errors, when the first 8 bytes of > + * the Message RAM have not been initialized (i.e. written to). > + * To work around this issue, the first 8 bytes are initialized here. > + */ > + m_can_fifo_write(priv, 0, M_CAN_FIFO_DATA(0), 0x0); > + m_can_fifo_write(priv, 0, M_CAN_FIFO_DATA(1), 0x0); > + > m_can_config_endisable(priv, false); > } > > Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: OpenPGP digital signature URL: