[PATCH 0/1] hw/i2c/aspeed: Fix old reg slave receive

[Peter Delevoryas]

Hey everyone,

I haven't gotten a chance to work on the Aspeed I2C controller in a little
while, but I finally started looking at it again and noticed the
old-register mode slave receive function (master-send-to-slave) does the
wrong thing for the first byte. See the commit message for details.

I noticed this because I have a qtest for slave mode rx in old-register mode
downstream [1] (I'm also working on a version of the test that can be
upstreamed) that broke when I updated our QEMU branch to the 7.1 release.
Previously I was using Klaus's original slave I2C patches from [2].

An example of the test running successfully with this change is pasted below,
for whatever that's worth.

Thanks,
Peter

[1]: 
https://github.com/facebook/openbmc/blob/helium/common/recipes-devtools/qemu/qemu/0008-hw-misc-Add-byte-by-byte-i2c-network-device.patch
[2]: 
https://lore.kernel.org/qemu-devel/20220331165737.1073520-4-its@irrelevant.dk/

# random seed: R02S5d2728d1347dc8b50533a0d85ebb1b02
# starting QEMU: exec build/qemu-system-arm -qtest unix:/tmp/qtest-711521.sock 
-qtest-log /dev/null -chardev socket,path=/tmp/qtest-711521.qmp,id=char0 -mon 
chardev=char0,mode=control -display none -machine fby35-bmc -netdev 
socket,id=socket0,udp=127.0.0.1:5000,localaddr=127.0.0.1:6000 -device 
i2c-netdev2,bus=aspeed.i2c.bus.0,address=0x32,netdev=socket0 -accel qtest
i2c_netdev2_class_init
i2c_netdev2_realize
i2c_netdev2_can_receive
1..2
# Start of arm tests
# Start of ast2600 tests
# Start of i2c tests
i2c_netdev2_handle_event: 1
../hw/misc/i2c-netdev2.c: tx [64, 00, 00]
../hw/misc/i2c-netdev2.c: tx [de]
../hw/misc/i2c-netdev2.c: tx [ad]
../hw/misc/i2c-netdev2.c: tx [be]
../hw/misc/i2c-netdev2.c: tx [ef]
i2c_netdev2_handle_event: 3
../hw/misc/i2c-netdev2.c: tx [00, 00, 00, 00]
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [01, 00]
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [01, 00]
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [01, 00]
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [01, 00]
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [01, 00]
ok 1 /arm/ast2600/i2c/write_in_old_byte_mode
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [20, 00, 00]
prev rx_buf: [00, 00, 00, 00, 00, 00, 00, 00, 00, 00]
next rx_buf: [20, 00, 00, 00, 00, 00, 00, 00, 00, 00]
i2c_netdev2_slave_mode_rx: rx_len=3
i2c_netdev2_slave_mode_rx: rx_len=3
i2c_netdev2_slave_mode_rx: guest OS ack rx, clearing rx_len
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [de]
prev rx_buf: [20, 00, 00, 00, 00, 00, 00, 00, 00, 00]
next rx_buf: [de, 00, 00, 00, 00, 00, 00, 00, 00, 00]
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: guest OS ack rx, clearing rx_len
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [ad]
prev rx_buf: [de, 00, 00, 00, 00, 00, 00, 00, 00, 00]
next rx_buf: [ad, 00, 00, 00, 00, 00, 00, 00, 00, 00]
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: guest OS ack rx, clearing rx_len
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [be]
prev rx_buf: [ad, 00, 00, 00, 00, 00, 00, 00, 00, 00]
next rx_buf: [be, 00, 00, 00, 00, 00, 00, 00, 00, 00]
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: guest OS ack rx, clearing rx_len
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [ef]
prev rx_buf: [be, 00, 00, 00, 00, 00, 00, 00, 00, 00]
next rx_buf: [ef, 00, 00, 00, 00, 00, 00, 00, 00, 00]
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: rx_len=1
i2c_netdev2_slave_mode_rx: guest OS ack rx, clearing rx_len
i2c_netdev2_can_receive
../hw/misc/i2c-netdev2.c: rx [ef, 00, 00, 00]
prev rx_buf: [ef, 00, 00, 00, 00, 00, 00, 00, 00, 00]
next rx_buf: [ef, 00, 00, 00, 00, 00, 00, 00, 00, 00]
i2c_netdev2_slave_mode_rx: rx_len=4
ok 2 /arm/ast2600/i2c/slave_mode_rx_byte_buf
# End of i2c tests
# End of ast2600 tests
# End of arm tests
i2c_netdev2_nic_cleanup

Peter Delevoryas (1):
  hw/i2c/aspeed: Fix old reg slave receive

 hw/i2c/aspeed_i2c.c         | 8 +++++---
 include/hw/i2c/aspeed_i2c.h | 1 +
 2 files changed, 6 insertions(+), 3 deletions(-)

-- 
2.37.1