Re: [PATCH v2 19/22] thunderbolt: Add Apple Silicon support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Legacy adapter detection logic is inverted, incorrectly setting the legacy flag for non-legacy TBT3 adapters.
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commit 870427df367f711b84dc3079eca08f8a726f8dcd
Author: Sven Peter <sven@kernel.org>

thunderbolt: Add Apple Silicon support

This commit adds a platform driver for the ACIO host router complex and
Native Host Interface (NHI) on Apple Silicon SoCs. It registers notifications
for Thunderbolt and USB4 partner modes on the Type-C bus to derive cable
details.

> diff --git a/drivers/thunderbolt/apple.c b/drivers/thunderbolt/apple.c
> new file mode 100644
> index 0000000000000..f4b16f60701e3
> --- /dev/null
> +++ b/drivers/thunderbolt/apple.c
[ ... ]
> +static int apple_cio_tbt_cable_info(struct apple_cio *acio,
> +				    struct typec_altmode *altmode, u32 *cable_info)
> +{
[ ... ]
> +	if (cable_mode & TBT_CABLE_ACTIVE_PASSIVE) {
> +		info |= TB_VSE_CAP_APPLE_CABLE_INFO_ACTIVE_CABLE;
> +		if (!(cable_mode & TBT_CABLE_LINK_TRAINING))
> +			info |= TB_VSE_CAP_APPLE_CABLE_INFO_BIDIR_LSRX;
> +	}
> +	if (TBT_ADAPTER(altmode->vdo))
> +		info |= TB_VSE_CAP_APPLE_CABLE_INFO_LEGACY_ADAPTER;

[Severity: Medium]
Does this logic correctly identify legacy adapters?

Looking at the definition in include/linux/usb/typec_tbt.h, TBT_ADAPTER()
extracts a 1 for TBT3 devices and a 0 for legacy adapters:

#define TBT_ADAPTER(_vdo_)              FIELD_GET(BIT(16), _vdo_)
#define   TBT_ADAPTER_LEGACY            0

Because of the implicit truthy check, this evaluates to false for actual
legacy adapters, omitting the TB_VSE_CAP_APPLE_CABLE_INFO_LEGACY_ADAPTER flag.
Conversely, it evaluates to true for non-legacy devices like TBT3 adapters,
erroneously applying the legacy adapter flag to them.

Should this check instead be compared directly against TBT_ADAPTER_LEGACY to
ensure the connection is configured correctly?

> +	if (TBT_CABLE_SPEED(cable_mode) == TBT_CABLE_10_AND_20GBPS)
> +		info |= TB_VSE_CAP_APPLE_CABLE_INFO_20_GBPS;
> +	if (orientation == TYPEC_ORIENTATION_REVERSE)
> +		info |= TB_VSE_CAP_APPLE_CABLE_INFO_ORIENTATION_REVERSE;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260906-b4-apple-soc-tbt-v2-0-1f80085f93fb@kernel.org?part=19