From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dong Aisheng Subject: [PATCH V4 3/3] can: m_can: add missing message RAM initialization Date: Fri, 7 Nov 2014 16:45:14 +0800 Message-ID: <1415349914-9145-3-git-send-email-b29396@freescale.com> References: <1415349914-9145-1-git-send-email-b29396@freescale.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , , , , , To: Return-path: Received: from mail-bn1bn0102.outbound.protection.outlook.com ([157.56.110.102]:55656 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751209AbaKGJvs (ORCPT ); Fri, 7 Nov 2014 04:51:48 -0500 In-Reply-To: <1415349914-9145-1-git-send-email-b29396@freescale.com> Sender: netdev-owner@vger.kernel.org List-ID: 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; } -- 1.9.1