On Thu, 22 Jan 2026, Jonathan Cavitt <[email protected]> wrote:
> Static analysis issue:
>
> In assert_port_valid, add a check to ensure port != PORT_NONE, as that
> is not a valid port. The check must be explicit to prevent a bad bit
> shift operation in the general case via short-circuiting. It's not
> likely this will ever come up in a real use case, but it's at least
> worth guarding against.
>
> It would probably also be pertinent to modify the behavior of the
> port_name function to correctly print PORT_NONE in this case, as
> currently the port would be reported as 'port @' by the debugger. But
> that should be done separately, and given port_name is mostly just a
> debug printing helper function anyways, fixing it is a low priority.
>
> Signed-off-by: Jonathan Cavitt <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_display.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> b/drivers/gpu/drm/i915/display/intel_display.c
> index 7491e00e3858..250f31bb5938 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -7828,7 +7828,8 @@ static bool intel_ddi_crt_present(struct intel_display
> *display)
>
> bool assert_port_valid(struct intel_display *display, enum port port)
> {
> - return !drm_WARN(display->drm,
> !(DISPLAY_RUNTIME_INFO(display)->port_mask & BIT(port)),
> + return !drm_WARN(display->drm,
> + !(port < 0 || DISPLAY_RUNTIME_INFO(display)->port_mask
> & BIT(port)),
That's a bunch of negatives put together, making one's head spin, but
the innermost part is supposed to be checking if the port is valid,
i.e. BIT(port) is set in ->port_mask.
This makes "port < 0" another condition for the port being valid, which
is not the case. The port is only valid if
port >= 0 && DISPLAY_RUNTIME_INFO(display)->port_mask & BIT(port)
BR,
Jani.
> "Platform does not support port %c\n",
> port_name(port));
> }
--
Jani Nikula, Intel
