Hello Damon, On 2026-06-01 10:59:27+08:00, Damon Ding wrote: > Hi Luca, > > On 5/30/2026 9:38 PM, Luca Ceresoli wrote: > > > On Sat May 30, 2026 at 3:33 PM CEST, Luca Ceresoli wrote: > > > > Meh, messed up with 'b4 review' :-/ Apologies > > > > "This sashiko report" [0] was about an enum being signed, so '== 0' could > > miss > > negative numbers coming from bogus DT values higher than 1^31. > > Ah, I agree. It would be better to add a new inline function to validate > that the lane count passed from DT is exactly 1, 2, or 4, just as > Sashiko suggested. > > >> > > > > And this was about "Additionally, does this check inadvertently allow 3, > > which is an invalid DisplayPort lane count?" > > Yes, the DisplayPort specification only allows lane counts of 1, 2, or > 4. I did miss the check for the invalid value 3 in the current code. > > (BTW: I did not find a common helper function in drm_dp_helper.h to > validate valid DP lane counts (1, 2, 4). I'm not sure if it would be > better to add a generic lane count validation function to the DP helper > library instead, to avoid duplicating the same functionality across > individual DP drivers. Perhaps other DP experts could provide some > advice on this.)
A bool function in common code, to be reused by all DP drivers, would be good.
