Daniel Golle <daniel@xxxxxxxxxxxxxx> writes:
> On Sun, May 14, 2023 at 04:53:43PM +0200, Simon Horman wrote:
>> On Sat, May 13, 2023 at 03:35:51PM +0200, Daniel Golle wrote:
>> > From: Alexander Couzens <lynxis@xxxxxxx>
>> >
>> > Add support for the MediaTek MT7981 SoC which is similar to the MT7986
>> > but with a newer IP cores and only 2x ARM Cortex-A53 instead of 4x.
>> > Unlike MT7986 the MT7981 can only connect a single wireless frontend,
>> > usually MT7976 is used for DBDC.
>> >
>> > Signed-off-by: Alexander Couzens <lynxis@xxxxxxx>
>> > Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
>>
>> ...
>>
>> > @@ -489,7 +516,10 @@ static int mt7986_wmac_adie_patch_7976(struct mt7915_dev *dev, u8 adie)
>> > rg_xo_01 = 0x1d59080f;
>> > rg_xo_03 = 0x34c00fe0;
>> > } else {
>> > - rg_xo_01 = 0x1959f80f;
>> > + if (is_mt7981(&dev->mt76))
>> > + rg_xo_01 = 0x1959c80f;
>> > + else if (is_mt7986(&dev->mt76))
>> > + rg_xo_01 = 0x1959f80f;
>>
>> Hi Daniel,
>>
>> rg_xo_01 will be used uninitialised below if we get here
>> and neither of the conditions above are true.
>>
>> Can this occur?
>
> No, it cannot occur. Either of is_mt7981() or is_mt7986() will return
> true, as the driver is bound via one of the two compatibles
> 'mediatek,mt7986-wmac' or newly added 'mediatek,mt7981-wmac'.
> Based on that the match_data is either 0x7986 or 0x7981, which is then
> used as chip_id, which is used by the is_mt7981() and is_mt7986()
> functions.
But what if later more changes are made, for example a third compatible
is added? It would be good to add a warning or something else to protect
that.
And I would not be a surpised if a compiler or static analyser would
even warn about the uninitialised variable.
--
https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
