Singer George Michael has said he deserved to be jailed last September for crashing his Range Rover while under the influence of cannabis.
Michael, 47, was given an eight-week sentence and fined after driving into the front of a photo shop in London.
In an interview with Chris Evans for BBC Radio 2's Breakfast Show, he said going to jail had been karma for repeatedly breaking the law.
Michael has recorded a cover of New Order's True Faith for Comic Relief.
It is the first song he has released since 2008.
In the interview, the singer says he is "ashamed" to have broken the law, and says he is now having treatment for his drug problems.
He describes himself as "the poster boy for cannabis".
In 2007 he admitted another charge of drug-driving and carried out community service.
"This was a hugely shameful thing to have done repeatedly," he told Evans. "So karmically I felt like I had a bill to pay. I went to prison, I paid my bill."
But the singer denied reports that he had been distressed during his time in north London's Pentonville prison.
"Remarkably enough, I know people must think it was a really horrific experience - it's so much easier to take any form of punishment if you believe you actually deserve it, and I did."
He said: "It wasn't a weekend break, put it that way. I didn't feel sorry for myself. I thought, 'Oh my God, this place is absolutely filthy, because it was Pentonville'. I just thought, you get your head down."
Michael was later transferred to Highpoint open prison in Suffolk.
He said that while he was there he gave his autograph to every single staff member and prisoner.
'I start again'
On his last night there, he says, he signed a guitar and was asked to put the date on it.
"The guy said it's the 10th of the 10th of the 10th. And I just thought 'that's so fitting'. It's like the clock rolling round to the end of something, tomorrow I start again."
Michael, whose real name is Georgios Panayiotou, first rose to fame as half of the pop duo Wham! in the 1980s.
His solo albums sold millions of copies and won numerous awards in the UK and in the US.
In recent years, he returned to the stage for his first full live shows in more than a decade and toured Europe, the US and Australia.
Michael's new single is a cover of the New Order song True Faith, which will be released on 13 March, with all proceeds going to Comic Relief.
The first part of George Michael's interview with Chris Evans will be broadcast on BBC Radio 2 at 0800 GMT on Monday 7 March with the second part at the same time on Tuesday 8 March.