S. R. Faruqi:

Ghalib has called the desert the 'door-less house of Majnun the desert-wanderer':

G{18,3}.

This is a good expression of the expansiveness of the desert and the nonexistence of any kind of barriers to entering it. In comparison to this, Mir's 'open door of the desert' seems pallid. But in truth Mir's verse is not devoid of points of its own. Because the desert is not his house, it's only a halting-place, and that too only to the extent that he used to spend night and day lying at its door. The door remained open at every hour, but with the true style of a darvesh he used to remain lying only at the door.

In the same way, he didn't enter the wine-house either. In his madness/wildness was a style of aloofness; he didn't consent to enter any door, whether it be that of the desert or that of the wine-house.

The image of the open door of the desert Mir has used in one other place, in the fourth divan [{1461,5}]:

ab dar-e baaz-e bayaabaa;N me;N qadam rakhye miir
kab talak tang rahe;N shahr kii diivaaro;N me;N

[now set foot in the open door of the desert, Mir
for how long would you remain confined within the walls of the city?]

[See also {95,11}.]

FWP:

SETS == EXCLAMATION
MOTIFS == DESERT; SOUND EFFECTS; WINE-HOUSE
NAMES
TERMS == VERSE-SET

Unusually, the whole verse contains no finite verb, yet it's not part of a verse-set. It's simply a reflection about 'the memory of those days'.

We get the sense that the speaker's present state is entirely different, so that those former times are nothing more than a cherished memory. But of course, we can't tell how it's different-- is he now (mystically) beyond all that? Physically incapable of all that? Bored by all that? Nostalgic for all that? Amused by the memory of all that? Casually chatting with an old friend? Dying? Dead?

The yaad-e ayyaame also helps to create an enjoyable sound echo with the either-or clauses in the second line: we have yaad at the start of the first line, then in the second line, both at the beginning and at the midpoint, yaa-d and yaa-d .

The door of the wine-house is almost always open, and inviting sounds and aromas tempt the passerby; in strong contrast, the desolate 'door' of the desert doesn't exactly beckon one to enter. Yet the speaker finds that in his memory, intriguingly, it's the door of the desert that was 'open'. Are we to think of the speaker as a faqir or beggar who was not actually permitted to enter the wine-house, so that the only (relatively?) open 'door' was that of the desert? And in any case, why didn't he ever enter the desert? SRF says it's because he was a darvesh, which is possible but of course not the only possibility. Here are more mysteries, more conjectures that we're invited (or required) to make for ourselves.