Just saw Lucas Stach's post "CAAM RNG trouble" from yesterday which seems to be describing this same issue - added to CC. On Tue, 2020-12-15 at 17:31 -0600, Robert Hancock wrote: > Hello, > > We have an iMX6D-based board which was previously using 5.4.x > kernels. > I have recently started testing v5.10.1 on this board and am running > into an issue with the CAAM RNG. The dmesg is getting output like > this > and all reads from /dev/hwrng are failing with EINVAL: > > [ 17.368368] caam_jr 2101000.jr: 2000025b: CCB: desc idx 2: RNG: > Hardware error > [ 17.375721] hwrng: no data available > [ 23.200255] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: > Hardware error > [ 23.215508] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: > Hardware error > [ 23.229249] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: > Hardware error > [ 23.243415] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: > Hardware error > [ 23.257809] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: > Hardware error > [ 23.272109] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: > Hardware error > > We are not using secure boot presently, if that matters. On 5.4, no > such issues and /dev/hwrng seems to work fine. > > I see there are some CAAM RNG changes between 5.4 and 5.10 but not > sure > which might be the cause? > > The CAAM initialization output on boot (same on working 5.4 and non- > working 5.10.1 kernels): > > [ 16.934253] caam 2100000.crypto: Entropy delay = 3200 > [ 17.000146] caam 2100000.crypto: Instantiated RNG4 SH0 > [ 17.060911] caam 2100000.crypto: Instantiated RNG4 SH1 > [ 17.067891] caam 2100000.crypto: device ID = 0x0a16010000000000 > (Era > 4) > [ 17.080289] caam 2100000.crypto: job rings = 2, qi = 0 > [ 17.113498] caam algorithms registered in /proc/crypto > [ 17.120099] caam 2100000.crypto: registering rng-caam >
