diff options
| author | Russell King <rmk+kernel@armlinux.org.uk> | 2019-06-02 15:13:00 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-06-03 15:16:37 -0700 |
| commit | 28e74a7cfd6403f0d1c0f8b10b45d6fae37b227e (patch) | |
| tree | b755263cde381c8daafcd4c3c1c67a7211a51ae6 /drivers/net/phy/sfp.c | |
| parent | 67c0aaa1eaec60e9dab301012bdebe6726ae04bd (diff) | |
net: sfp: read eeprom in maximum 16 byte increments
Some SFP modules do not like reads longer than 16 bytes, so read the
EEPROM in chunks of 16 bytes at a time. This behaviour is not specified
in the SFP MSAs, which specifies:
"The serial interface uses the 2-wire serial CMOS E2PROM protocol
defined for the ATMEL AT24C01A/02/04 family of components."
and
"As long as the SFP+ receives an acknowledge, it shall serially clock
out sequential data words. The sequence is terminated when the host
responds with a NACK and a STOP instead of an acknowledge."
We must avoid breaking a read across a 16-bit quantity in the diagnostic
page, thankfully all 16-bit quantities in that page are naturally
aligned.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/phy/sfp.c')
| -rw-r--r-- | drivers/net/phy/sfp.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c index d4635c2178d1..71812be0ac64 100644 --- a/drivers/net/phy/sfp.c +++ b/drivers/net/phy/sfp.c @@ -281,6 +281,7 @@ static int sfp_i2c_read(struct sfp *sfp, bool a2, u8 dev_addr, void *buf, { struct i2c_msg msgs[2]; u8 bus_addr = a2 ? 0x51 : 0x50; + size_t this_len; int ret; msgs[0].addr = bus_addr; @@ -292,11 +293,26 @@ static int sfp_i2c_read(struct sfp *sfp, bool a2, u8 dev_addr, void *buf, msgs[1].len = len; msgs[1].buf = buf; - ret = i2c_transfer(sfp->i2c, msgs, ARRAY_SIZE(msgs)); - if (ret < 0) - return ret; + while (len) { + this_len = len; + if (this_len > 16) + this_len = 16; - return ret == ARRAY_SIZE(msgs) ? len : 0; + msgs[1].len = this_len; + + ret = i2c_transfer(sfp->i2c, msgs, ARRAY_SIZE(msgs)); + if (ret < 0) + return ret; + + if (ret != ARRAY_SIZE(msgs)) + break; + + msgs[1].buf += this_len; + dev_addr += this_len; + len -= this_len; + } + + return msgs[1].buf - (u8 *)buf; } static int sfp_i2c_write(struct sfp *sfp, bool a2, u8 dev_addr, void *buf, |