I think Bloom still hasn't mentioned it, despite his obsession with both poems, but doesn't he imply - and isn't it likely - that Browning had "Tom o'Bedlam" in mind when he wrote "Childe Roland"?
In Edgar's song in King Lear, Childe Roland comes to an apparently already identified dark tower and is noticed by some kind of apparently already identified male, one assumes a giant or some other monster with power of speech, who (mis?)identifies him as English by the smell of his blood, and then seems to repeat this as a kind of threatening mantra; we're to understand they're probably going to fight, and as Roland is our countryman but isn't yet a knight we're worried about him. Giants who can smell your blood are bad news. But this may be how Roland will become a knight, by overcoming a high profile challenge. So we're rooting for him too. We hope and fear.
Wouldn't be worth any of this attention except that Browning develops these verses into his most, maybe only, enigmatic poem.
"Tom o'Bedlam" is unfortunately towerless, but it's another freaky song with quest elements that Edgar puts all of us in mind of because Tom o'Bedlam, to what extent influenced by that particular anonymous song we'll never know, is exactly who Edgar's pretending to be when he sings the Roland fragment. The unequivocal quest language is all in the last stanza of "Tom o'Bedlam":
With a host of furious fancies
Whereof I am commander,
With a burning spear and a horse of air,
To the wilderness I wander.
By a knight of ghosts and shadows
I summoned am to tourney
Ten leagues beyond the wild world's end.
Methinks it is no journey.
A visionary quest, thus more like Browning's Roland's than Shakespeare's Edgar's Roland's. We don't see who or what the later Roland eventually confronts, though strangely we do see a bunch of ghosts of defeated knights at the very end. Roland apparently has been summoned to fight the denizen of the Dark Tower, the tower does seem to exist somewhere outside reality as the landscape magically shifts on Roland at least twice on his way there, and the fact that it does so twice in what may be rapid succession means that in terms of distance it really might not have been much of a journey.
The first four lines are an iffier fit, beyond the obvious fact that he's wandered into the wilderness: Browning's Roland doesn't have a horse of air, though he does have no horse, and does wander by a very skinny one he isn't fond of. I don't think we're told anything about his weapon, unless the horn thing he blows at the end counts. Whether he has a host of furious fancies depends on how you interpret the poem - for example, the poem itself may be such a host if he's hallucinating, or the childe may be a poet approaching a fight with some force obstacular to the furious fancies of poetry.
Some earlier lines in "Tom o'Bedlam" may also be relevant:
I know more than Apollo,
For oft, when he lies sleeping
I see the stars at bloody wars
In the wounded welkin weeping [...]
A sky weeping at its stars shedding one another's blood, rhetoric curiously Lear-like (Bloom wants Shakespeare to have written this but agrees there's no proof), reflects the waste Browning's Roland passes through, where the mud seems made from the blood shed in some vast and pointless ancient battle. A cosmos that has itself been wounded is presumably a projection, hence something we might expect from mad Tom, not knight-caste Roland, but it's a vision they've both experienced. "Tom o'Bedlam" is largely a moving account of the terrible life lived by someone mentally ill four hundred years ago, but the flashes of prophetic vision and intensity of the verses do make one think of the lot of poets (who Shakespeare's Theseus considered at one with madmen and lovers), who maybe see what the rest of us can't but also were generally social outcasts who ended up starving in garrets.
Tom may know more than Apollo, but it's not clear even he thinks he's going to win this fight with a knight of ghosts and shadows, no matter how hot his spear is burning. Can such entities be fought, assuming they quite exist? Can they be defeated? The poem doesn't say, it just ends. Like Edgar's, like Browning's. A fight you were doomed to fight but whose outcome is unknowable and pushed past the margin of observation, maybe of imagination, inevitably makes us think of the Big Question Mark that's death, but of course the fate of a poet's poems, one point of which may be to carry the poet forward into some kind of life beyond death, are as much of a question mark - who will read them, and with what understanding, and for how long? The second death of not being read, or not read correctly, or not staying somehow alive in what's read and understood, has to be a big worry. But that's a fight you come to armed, with talent and tricks and fancies or whatever might suffice, unlike your bout with natural death, which you're going to ultimately lose.
And the bout with death is fought in this world. Beyond the world - could this be beyond one's death?
Like I said, it's a story you can't not dimly make out after reading enough Bloom, though he's of course usually more interested in the Influence angle when looking at "Childe Roland," but I don't remember him flat out telling it.