[PATCH net-next] net: sfp: Use smaller chunk size when reading I2C data
From: Robert Hancock <hidden>
Date: 2019-05-31 19:18:35
Subsystem:
ethernet phy library, networking drivers, sff/sfp/sfp+ module support, the rest · Maintainers:
Andrew Lunn, Heiner Kallweit, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Russell King, Linus Torvalds
The SFP driver was reading up to 256 bytes of I2C data from the SFP module in a single chunk. However, some I2C controllers do not support reading that many bytes in a single transaction. Change to use a more compatible 16-byte chunk size, since this is not performance critical. Signed-off-by: Robert Hancock <redacted> --- drivers/net/phy/sfp.c | 38 ++++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-)
diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index 6b6c83d..23a40a7 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c@@ -1651,7 +1651,7 @@ static int sfp_module_info(struct sfp *sfp, struct ethtool_modinfo *modinfo) static int sfp_module_eeprom(struct sfp *sfp, struct ethtool_eeprom *ee, u8 *data) { - unsigned int first, last, len; + unsigned int first, last; int ret; if (ee->len == 0)
@@ -1659,26 +1659,36 @@ static int sfp_module_eeprom(struct sfp *sfp, struct ethtool_eeprom *ee, first = ee->offset; last = ee->offset + ee->len; - if (first < ETH_MODULE_SFF_8079_LEN) { - len = min_t(unsigned int, last, ETH_MODULE_SFF_8079_LEN); - len -= first; - ret = sfp_read(sfp, false, first, data, len); + while (first < last) { + bool a2; + unsigned int this_addr, len; + + if (first < ETH_MODULE_SFF_8079_LEN) { + len = min_t(unsigned int, last, + ETH_MODULE_SFF_8079_LEN); + len -= first; + a2 = false; + this_addr = first; + } else { + len = min_t(unsigned int, last, + ETH_MODULE_SFF_8472_LEN); + len -= first; + a2 = true; + this_addr = first - ETH_MODULE_SFF_8079_LEN; + } + /* Some I2C adapters cannot read 256 bytes in a single read. + * Use a smaller chunk size to ensure we are within limits. + */ + len = min_t(unsigned int, len, 16); + + ret = sfp_read(sfp, a2, this_addr, data, len); if (ret < 0) return ret; first += len; data += len; } - if (first < ETH_MODULE_SFF_8472_LEN && last > ETH_MODULE_SFF_8079_LEN) { - len = min_t(unsigned int, last, ETH_MODULE_SFF_8472_LEN); - len -= first; - first -= ETH_MODULE_SFF_8079_LEN; - - ret = sfp_read(sfp, true, first, data, len); - if (ret < 0) - return ret; - } return 0; }
--
1.8.3.1