The transfer window closes on Tuesday 31 August, giving clubs just four days to complete any last-minute deals.
Sunderland have been active this summer and Johnson admitted he is still in the market for players:
"We'll still be active and we're certainly in the market.,” Johnson said.
“But your options do narrow because of the quality required.
“You also want players who have been active through pre-season and of course, you can only use a certain number of loan players at any one time.
“We might determine to use the loans with an obligation [to buy]. I'd always say that generally I'd rather take a loan who I believe could be turned into a permanent at the end of it, albeit in exceptional circumstances you can't do that.”
Here, we look at all the latest news from around League One:
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1. Portsmouth targeting Coventry winger
Portsmouth boss Danny Cowley is targeting Coventry City winger Jordan Shipley as he looks to bolster his side’s attacking options (The Portsmouth News). (Photo by Pete Norton/Getty Images) Photo: Pete Norton
2. Arsenal youngster set for south-coast
Promising Arsenal midfielder Miguel Azeez is closing-in on a move to Fratton Park to join Danny Cowley’s squad at Portsmouth. Azeez is one of the most highly-rated youngsters in the Arsenal academy (football.london). (Photo by James Chance/Getty Images) Photo: James Chance
3. Paul Cook anticipates a busy end to the window at Ipswich Town
Ipswich Town boss Paul Cook has admitted that he “just loves signing players” and revealed that he is trying to get Mark Ashton, the club’s CEO “to sign a player from Azerbaijan” ahead of an anticipated busy end to the transfer window at Portman Road. (East Anglian Daily Times). (Photo by Pete Norton/Getty Images) Photo: Pete Norton
4. Lincoln ‘miss out’ on signing to League One rivals
Lincoln City have been pipped to the signing of Bristol Rovers’ Brandon Hanlan by Wycombe Wanderers. Hanlan, 24, has signed a three-year contract at Adams Park (The72). (Photo by David Rogers/Getty Images) Photo: David Rogers