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Message-ID: <DB8PR04MB67950FA3AD93C22DE358646AE6320@DB8PR04MB6795.eurprd04.prod.outlook.com>
Date: Tue, 29 Sep 2020 04:03:50 +0000
From: Joakim Zhang <qiangqing.zhang@....com>
To: "mkl@...gutronix.de" <mkl@...gutronix.de>,
"linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V3 1/3] can: flexcan: initialize all flexcan memory for
ECC function
> -----Original Message-----
> From: Joakim Zhang <qiangqing.zhang@....com>
> Sent: 2020年9月29日 2:03
> To: mkl@...gutronix.de; linux-can@...r.kernel.org
> Cc: netdev@...r.kernel.org; dl-linux-imx <linux-imx@....com>
> Subject: [PATCH V3 1/3] can: flexcan: initialize all flexcan memory for ECC
> function
>
> One issue was reported at a baremetal environment, which is used for FPGA
> verification. "The first transfer will fail for extended ID format(for both 2.0B and
> FD format), following frames can be transmitted and received successfully for
> extended format, and standard format don't have this issue. This issue
> occurred randomly with high possiblity, when it occurs, the transmitter will
> detect a BIT1 error, the receiver a CRC error. According to the spec, a
> non-correctable error may cause this transfer failure."
>
> With FLEXCAN_QUIRK_DISABLE_MECR quirk, it supports correctable errors,
> disable non-correctable errors interrupt and freeze mode. Platform has ECC
> hardware support, but select this quirk, this issue may not come to light.
> Initialize all FlexCAN memory before accessing them, at least it can avoid
> non-correctable errors detected due to memory uninitialized.
> The internal region can't be initialized when the hardware doesn't support ECC.
>
> According to IMX8MPRM, Rev.C, 04/2020. There is a NOTE at the section
> 11.8.3.13 Detection and correction of memory errors:
> "All FlexCAN memory must be initialized before starting its operation in order
> to have the parity bits in memory properly updated. CTRL2[WRMFRZ] grants
> write access to all memory positions that require initialization, ranging from
> 0x080 to 0xADF and from 0xF28 to 0xFFF when the CAN FD feature is enabled.
> The RXMGMASK, RX14MASK, RX15MASK, and RXFGMASK registers need to be
> initialized as well. MCR[RFEN] must not be set during memory initialization."
>
> Memory range from 0x080 to 0xADF, there are reserved memory
> (unimplemented by hardware, e.g. only configure 64 MBs), these memory can
> be initialized or not.
> In this patch, initialize all flexcan memory which includes reserved memory.
>
> In this patch, create FLEXCAN_QUIRK_SUPPORT_ECC for platforms which has
> ECC feature. If you have a ECC platform in your hand, please select this qurik to
> initialize all flexcan memory firstly, then you can select
> FLEXCAN_QUIRK_DISABLE_MECR to only enable correctable errors.
>
> Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> ---
> ChangeLogs:
> V1->V2:
> * update commit messages, add a datasheet reference.
> * initialize block memory instead of trivial memory.
> * inilialize reserved memory.
> V2->V3:
> * add FLEXCAN_QUIRK_SUPPORT_ECC quirk.
> * remove init_ram struct.
> ---
> drivers/net/can/flexcan.c | 50
> +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index
> e86925134009..0ae7436ee6ef 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -239,6 +239,8 @@
> #define FLEXCAN_QUIRK_SETUP_STOP_MODE BIT(8)
> /* Support CAN-FD mode */
> #define FLEXCAN_QUIRK_SUPPORT_FD BIT(9)
> +/* support memory detection and correction */ #define
> +FLEXCAN_QUIRK_SUPPORT_ECC BIT(10)
>
> /* Structure of the message buffer */
> struct flexcan_mb {
> @@ -1292,6 +1294,51 @@ static void flexcan_set_bittiming(struct net_device
> *dev)
> return flexcan_set_bittiming_ctrl(dev); }
>
> +static void flexcan_init_ram(struct net_device *dev) {
> + struct flexcan_priv *priv = netdev_priv(dev);
> + struct flexcan_regs __iomem *regs = priv->regs;
> + u32 reg_ctrl2;
> +
> + /* 11.8.3.13 Detection and correction of memory errors:
> + * CTRL2[WRMFRZ] grants write access to all memory positions that
> + * require initialization, ranging from 0x080 to 0xADF and
> + * from 0xF28 to 0xFFF when the CAN FD feature is enabled.
> + * The RXMGMASK, RX14MASK, RX15MASK, and RXFGMASK registers
> need to
> + * be initialized as well. MCR[RFEN] must not be set during memory
> + * initialization.
> + */
> + reg_ctrl2 = priv->read(®s->ctrl2);
> + reg_ctrl2 |= FLEXCAN_CTRL2_WRMFRZ;
> + priv->write(reg_ctrl2, ®s->ctrl2);
> +
> + /* ranging from 0x0080 to 0x0ADF, ram details as below list:
> + * 0x0080--0x087F: 128 MBs
> + * 0x0880--0x0A7F: 128 RXIMRs
> + * 0x0A80--0x0A97: 6 RXFIRs
> + * 0x0A98--0x0A9F: Reserved
> + * 0x0AA0--0x0AA3: RXMGMASK
> + * 0x0AA4--0x0AA7: RXFGMASK
> + * 0x0AA8--0x0AAB: RX14MASK
> + * 0x0AAC--0x0AAF: RX15MASK
> + * 0x0AB0--0x0ABF: TX_SMB
> + * 0x0AC0--0x0ACF: RX_SMB0
> + * 0x0AD0--0x0ADF: RX_SMB1
> + */
> + memset_io((void __iomem *)regs + 0x80, 0, 0xadf - 0x80 + 1);
> +
> + /* ranging from 0x0F28 to 0x0FFF when CAN FD feature is enabled,
> + * ram details as below list:
> + * 0x0F28--0x0F6F: TX_SMB_FD
> + * 0x0F70--0x0FB7: RX_SMB0_FD
> + * 0x0FB8--0x0FFF: RX_SMB0_FD
> + */
> + memset_io((void __iomem *)regs + 0xf28, 0, 0xfff - 0xf28 + 1);
Sorry, should be this, please ignore it first.
if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
memset_io((void __iomem *)regs + 0xf28, 0, 0xfff - 0xf28 + 1);
Best Regards,
Joakim Zhang
> + reg_ctrl2 &= ~FLEXCAN_CTRL2_WRMFRZ;
> + priv->write(reg_ctrl2, ®s->ctrl2);
> +}
> +
> /* flexcan_chip_start
> *
> * this functions is entered with clocks enabled @@ -1316,6 +1363,9 @@
> static int flexcan_chip_start(struct net_device *dev)
> if (err)
> goto out_chip_disable;
>
> + if (priv->devtype_data->quirks & FLEXCAN_QUIRK_SUPPORT_ECC)
> + flexcan_init_ram(dev);
> +
> flexcan_set_bittiming(dev);
>
> /* MCR
> --
> 2.17.1
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