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realtek-poe: Add PSE ID quirk for Zyxel GS1900-24HP-v1 #6

Merged
merged 3 commits into from
Jul 3, 2022
Merged

realtek-poe: Add PSE ID quirk for Zyxel GS1900-24HP-v1 #6

merged 3 commits into from
Jul 3, 2022

Commits on Jun 28, 2022

  1. realtek-poe: Fix expression expansion in GET_STR() macro 

    What does GET_STR() expand to? For simple cases, it's trivial.
Operator precedence in C can result in unexpected behavior when
"a" or "b" are complex expressions:

    GET_STR(i + 2, array)
      ==> (i + 2 < ARRAY_SIZE() ? array[i + 2] : NULL);
    GET_STR(1, array + i)
      ==> (1 < ARRAY_SIZE() ? array + i[1] : NULL)

The former incorrectly checks the array size against the second term,
but dereferences a higher index. It can result in out-of-bounds reads.
The latter results in nonsense code

Macro expansions can be fixed by enclosing expresions in parentheses.
This ensures expressions get evaluated in the expected order. Add
parentheses in GET_STR(), where appropriate.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
    @mrnuke
    mrnuke committed Jun 28, 2022
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  2. realtek-poe: Fix status for devices with more than 8 PoE ports 

    Only status data for the first 8 ports was requested. Most devices
have 8 ports, and the reply packet has room for 8 ports. It was the
perfect match!

People quickly figured out realtek-poe works for unicorn switches with
more than 8 PoE ports. And so they did. And they increased MAX_PORT
without regards to the out-of-bounds access problem they created. And
realtek-poe refused to crash!

Command 0x2a has proven to be unreliable for devices with more than
8 ports. It returns garbage for ports > 8, even on switchea with more
than 8 PoE ports.

Command 0x28 is more reliable. It only sends 4 port statuses per
packet, but returns correct data. If the port number exceeds the total
ports on the device, it correctly returns 0xff.

Replace port status query with command 0x28.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
    @mrnuke
    mrnuke committed Jun 28, 2022
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  3. realtek-poe: Add PSE ID quirk for Zyxel GS1900-24HP-v1 

    The "set global power budget" command contains a PSE controller in its
argument list. This was hardcoded to 0. On some switches, commands to
PSE 0 do nothing. In those cases, the set budget command won't stick.
The power budget remains at its default value, usually 0. Because of
this, ports remain stuck in the "Requesting power" state.

To solve this, send the budget command to the correct PSE ID or set of
IDs. Use a mask to encode which PSE IDs neet the set budget command.
When the "compatible" devicetree string matches Zyxel GS1900-24HP-v1,
set the mask to 0xff, to command PS ID's 0->7. The vendor firmware
also uses ID's 0->7. This enables power delivery to PoE sinks.

Tested-by: Martin Kennedy hurricos@gmail.com
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
    @mrnuke
    mrnuke committed Jun 28, 2022
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