1. 30 10月, 2021 2 次提交
    • J
      igb: unbreak I2C bit-banging on i350 · a97f8783
      Jan Kundrát 提交于
      The driver tried to use Linux' native software I2C bus master
      (i2c-algo-bits) for exporting the I2C interface that talks to the SFP
      cage(s) towards userspace. As-is, however, the physical SCL/SDA pins
      were not moving at all, staying at logical 1 all the time.
      
      The main culprit was the I2CPARAMS register where igb was not setting
      the I2CBB_EN bit. That meant that all the careful signal bit-banging was
      actually not being propagated to the chip pads (I verified this with a
      scope).
      
      The bit-banging was not correct either, because I2C is supposed to be an
      open-collector bus, and the code was driving both lines via a totem
      pole. The code was also trying to do operations which did not make any
      sense with the i2c-algo-bits, namely manipulating both SDA and SCL from
      igb_set_i2c_data (which is only supposed to set SDA). I'm not sure if
      that was meant as an optimization, or was just flat out wrong, but given
      that the i2c-algo-bits is set up to work with a totally dumb GPIO-ish
      implementation underneath, there's no need for this code to be smart.
      
      The open-drain vs. totem-pole is fixed by the usual trick where the
      logical zero is implemented via regular output mode and outputting a
      logical 0, and the logical high is implemented via the IO pad configured
      as an input (thus floating), and letting the mandatory pull-up resistors
      do the rest. Anything else is actually wrong on I2C where all devices
      are supposed to have open-drain connection to the bus.
      
      The missing I2CBB_EN is set (along with a safe initial value of the
      GPIOs) just before registering this software I2C bus.
      
      The chip datasheet mentions HW-implemented I2C transactions (SFP EEPROM
      reads and writes) as well, but I'm not touching these for simplicity.
      
      Tested on a LR-Link LRES2203PF-2SFP (which is an almost-miniPCIe form
      factor card, a cable, and a module with two SFP cages). There was one
      casualty, an old broken SFP we had laying around, which was used to
      solder some thin wires as a DIY I2C breakout. Thanks for your service.
      With this patch in place, I can `i2cdump -y 3 0x51 c` and read back data
      which make sense. Yay.
      Signed-off-by: NJan Kundrát <jan.kundrat@cesnet.cz>
      See-also: https://www.spinics.net/lists/netdev/msg490554.htmlReviewed-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
      Tested-by: NTony Brelinski <tony.brelinski@intel.com>
      Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
      a97f8783
    • Y
      intel: Simplify bool conversion · 3c6f3ae3
      Yang Li 提交于
      Fix the following coccicheck warning:
      ./drivers/net/ethernet/intel/i40e/i40e_xsk.c:229:35-40: WARNING:
      conversion to bool not needed here
      ./drivers/net/ethernet/intel/ice/ice_xsk.c:399:35-40: WARNING:
      conversion to bool not needed here
      Reported-by: NAbaci Robot <abaci@linux.alibaba.com>
      Signed-off-by: NYang Li <yang.lee@linux.alibaba.com>
      Tested-by: NTony Brelinski <tony.brelinski@intel.com>
      Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
      3c6f3ae3
  2. 29 10月, 2021 38 次提交