From: "Modilaynen, Pavel" <pavel.modilaynen@volvocars.com>
To: "mkl@pengutronix.de" <mkl@pengutronix.de>
Cc: "drew@beagleboard.org" <drew@beagleboard.org>,
"linux-can@vger.kernel.org" <linux-can@vger.kernel.org>,
"menschel.p@posteo.de" <menschel.p@posteo.de>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"will@macchina.cc" <will@macchina.cc>
Subject: Re: [net-next 6/6] can: mcp251xfd: mcp251xfd_regmap_crc_read(): work around broken CRC on TBC register
Date: Tue, 7 Dec 2021 16:53:12 +0000 [thread overview]
Message-ID: <PR3P174MB0112D073D0E5E080FAAE8510846E9@PR3P174MB0112.EURP174.PROD.OUTLOOK.COM> (raw)
Hello Marc,
We observe the very similar issue with MCP2517FD.
>The CRC errors the patch works around are CRC errors introduced by a
>chip erratum, not by electromagnetic interference. In my observation
Are you referring this errata doc
https://datasheet.octopart.com/MCP2517FD-H-JHA-Microchip-datasheet-136609045.pdf ?
We have the similar CRC read errors but
the lowest byte is not 0x00 and 0x80, it's actually 0x0x or 0x8x, e.g.
mcp251xfd spi0.0 can0: CRC read error at address 0x0010 (length=4, data=82 d1 fa 6c, CRC=0xd9c2) retrying.
0xb0 0x10 0x04 0x82 0xd1 0xfa 0x6c => 0x59FD (not matching)
but if I flip the first received bit (highest bit in the lowest byte):
0xb0 0x10 0x04 0x02 0xd1 0xfa 0x6c => 0xD9C2 (matching!)
So, your fix covers only the case of 0x00 and 0x80,
do you think that the workaround should be extended so check
(buf_rx->data[0] == 0x0 || buf_rx->data[0] == 0x80)) {
turns into
((buf_rx->data[0] & 0xf0) == 0x0 || (buf_rx->data[0] & 0xf0) == 0x80)) {
Errata, actually says
"Only bits 7/15/23/31 of the following registers can be affected:"
So, we could basically, in simplest case flip bit 31 and re-check CRC without any check of
rx->data[0]....
Regards,
Pavel
next prev reply other threads:[~2021-12-07 16:53 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 8:01 pull-request: can-next 2021-04-07 Marc Kleine-Budde
2021-04-07 8:01 ` [net-next 1/6] can: skb: alloc_can{,fd}_skb(): set "cf" to NULL if skb allocation fails Marc Kleine-Budde
2021-04-07 8:01 ` [net-next 2/6] can: m_can: m_can_receive_skb(): add missing error handling to can_rx_offload_queue_sorted() call Marc Kleine-Budde
2021-04-07 8:01 ` [net-next 3/6] can: c_can: remove unused enum BOSCH_C_CAN_PLATFORM Marc Kleine-Budde
2021-04-07 8:01 ` [net-next 4/6] can: mcp251xfd: add BQL support Marc Kleine-Budde
2021-04-07 8:01 ` [net-next 5/6] can: mcp251xfd: mcp251xfd_regmap_crc_read_one(): Factor out crc check into separate function Marc Kleine-Budde
2021-04-07 8:01 ` [net-next 6/6] can: mcp251xfd: mcp251xfd_regmap_crc_read(): work around broken CRC on TBC register Marc Kleine-Budde
2021-04-21 19:58 ` Drew Fustini
2021-04-22 7:18 ` Marc Kleine-Budde
2021-04-22 16:46 ` Patrick Menschel
2021-05-07 7:25 ` Marc Kleine-Budde
2021-05-07 8:21 ` Patrick Menschel
2021-05-07 8:25 ` Marc Kleine-Budde
2021-05-08 18:36 ` Patrick Menschel
2021-05-09 7:46 ` Patrick Menschel
2021-05-10 7:45 ` Marc Kleine-Budde
2021-05-20 10:29 ` Patrick Menschel
2021-05-10 7:43 ` Marc Kleine-Budde
2021-12-07 16:53 ` Modilaynen, Pavel [this message]
2021-12-08 8:54 ` Marc Kleine-Budde
2021-12-09 10:22 ` Thomas.Kopp
2021-12-09 11:17 ` AW: " Sven Schuchmann
2021-12-09 11:27 ` Marc Kleine-Budde
2021-12-09 12:53 ` AW: " Sven Schuchmann
2021-12-13 22:12 ` Modilaynen, Pavel
2021-12-21 22:24 ` Thomas.Kopp
2022-06-21 14:25 ` Marc Kleine-Budde
2022-06-22 8:19 ` Marc Kleine-Budde
2022-06-22 13:47 ` Thomas.Kopp
2022-06-26 19:14 ` Marc Kleine-Budde
2021-05-07 22:36 ` Drew Fustini
2021-05-08 12:30 ` Marc Kleine-Budde
2021-04-07 22:10 ` pull-request: can-next 2021-04-07 patchwork-bot+netdevbpf
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