From mboxrd@z Thu Jan 1 00:00:00 1970 From: socketcan@hartkopp.net (Oliver Hartkopp) Date: Fri, 07 Nov 2014 12:53:10 +0100 Subject: [PATCH V4 3/3] can: m_can: add missing message RAM initialization In-Reply-To: <1415349914-9145-3-git-send-email-b29396@freescale.com> References: <1415349914-9145-1-git-send-email-b29396@freescale.com> <1415349914-9145-3-git-send-email-b29396@freescale.com> Message-ID: <545CB2A6.1010703@hartkopp.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Thanks! Hopefully we can manage to push the patch series via can/master ;-) Regards, Oliver On 07.11.2014 09:45, Dong Aisheng wrote: > The M_CAN message RAM is usually equipped with a parity or ECC functionality. > But RAM cells suffer a hardware reset and can therefore hold arbitrary > content at startup - including parity and/or ECC bits. > > To prevent the M_CAN controller detecting checksum errors when reading > potentially uninitialized TX message RAM content to transmit CAN > frames the TX message RAM has to be written with (any kind of) initial > data. > > Signed-off-by: Dong Aisheng > --- > ChangeLog: > v3-v4: > * initialize the entire Message RAM in use instead of only 8 bytes > since this is a valid and needed initialization process. > Patch title also changed. > --- > drivers/net/can/m_can/m_can.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c > index eee1533..de742d0 100644 > --- a/drivers/net/can/m_can/m_can.c > +++ b/drivers/net/can/m_can/m_can.c > @@ -1114,7 +1114,7 @@ static int m_can_of_parse_mram(struct platform_device *pdev, > struct resource *res; > void __iomem *addr; > u32 out_val[MRAM_CFG_LEN]; > - int ret; > + int i, start, end, ret; > > /* message ram could be shared */ > res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram"); > @@ -1165,6 +1165,15 @@ static int m_can_of_parse_mram(struct platform_device *pdev, > priv->mcfg[MRAM_TXE].off, priv->mcfg[MRAM_TXE].num, > priv->mcfg[MRAM_TXB].off, priv->mcfg[MRAM_TXB].num); > > + /* initialize the entire Message RAM in use to avoid possible > + * ECC/parity checksum errors when reading an uninitialized buffer > + */ > + start = priv->mcfg[MRAM_SIDF].off; > + end = priv->mcfg[MRAM_TXB].off + > + priv->mcfg[MRAM_TXB].num * TXB_ELEMENT_SIZE; > + for (i = start; i < end; i += 4) > + writel(0x0, priv->mram_base + i); > + > return 0; > } > >