Comment 9 for bug 1917203

I've just tried Surajee's patch on Ubuntu's latest kernel 5.11.0-11 for upcoming Hirsute and it consistently unlatches IOMMU after 6 x 20 msec tries on my Ryzen 2400G. Mainline 5.12-rc2 gave identical results.

Paul Menzel too gets failure even after 10 x 20 msecs on a 2200G and regards so long a delay as most unacceptable. Alexander Monakov's very simple patch always works for me but I haven't seen data from other people. Surajee has mentioned problems with it for some part of AMD's product range and, as one of AMD's IOMMU experts down at Austen Texas, he should know his onions :-).

I would be tempted to run with the patch (11 x 20 msecs), log the exit count number and get some user feedback. Hopefully an improved patch will emerge! AMD may have commercial as well as technical reasons not leave it unaddressed.

Best regards