The prosecution in the Cy Walsh case has indicated it will concede he was mentally incompetent when he allegedly murdered his father, former Adelaide Crows coach Phil Walsh.

The 55-year-old was repeatedly stabbed at his Somerton Park home in Adelaide's beachside western suburbs in July last year.

His son, 27-year-old Cy Walsh, was charged with murder and has been detained in a secure psychiatric facility.

He pleaded not guilty to murdering his father by reason of mental incompetence, and the prosecution told the South Australian Supreme Court it would accept that plea.

If the court finds him not guilty of murder by reason of mental incompetence he would be subjected to a lifetime psychiatric supervision order.

Prosecutor Lucy Boord told the court in the mention hearing:

"I can indicate that the Director [of Public Prosecutions] will concede that Mr Walsh was mentally incompetent at the time of the offence.

"I understand there will be a similar concession down the track in respect to the objective elements."

She said she had requested today's hearing be an open court hearing to allow the media to report on the proceedings.

Director of Public Prosecutions Adam Kimber SC said if the court found Walsh mentally incompetent at the time of his father's death, the prosecution would not oppose that finding.

"The prosecution's position has been reached after reviewing all relevant material gathered by SAPol in the course of its investigation, the reports of the forensic psychiatrists who have examined Mr Cy Walsh and following consultation with relevant parties," Mr Kimber said in a statement.

"I emphasise that no finding has yet been made by the court."

Most of the evidence in the case remains heavily suppressed, with submissions on suppressions to be heard in September.

The next hearing has been scheduled for September 28.