Hi Pablo, It seems to be working with your suggested change and PR enabled: ``` root@xxxx:/dev# dd bs=256 count=10 if=/dev/hwrng of=/dev/null 10+0 records in 10+0 records out 2560 bytes (2.6 kB, 2.5 KiB) copied, 14.5987 s, 0.2 kB/s root@xxxx:/dev# ``` Thanks! Best regards, Fredrik On Mon, Aug 30, 2021 at 08:49:25AM -0300, Fabio Estevam wrote: > Hi Fredrik, > > On Mon, Aug 30, 2021 at 8:22 AM Fredrik Yhlen <fredrik.yhlen@xxxxxxxxx> wrote: > > > > Hi, > > > > We're having problems with hwrng on a board with imx6sx (soloX) running Linux > > 5.10.x. mainline, and I have tracked it down to this commit > > '358ba762d9f1d4ba99ab31ef12bc28014b22f4c9' as being the culprit. > > > > The caam_jr driver spits out lots of messages when attempting to read from /dev/hwrng: > > ``` > > [29717.629041] hwrng: no data available > > [29727.859008] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG: Hardware error > > ``` > > > > ``` > > caam_jr 2101000.jr0: 2000025b: CCB: desc idx 2: RNG: Hardware error. > > caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error. > > caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error. > > caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error. > > caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error. > > caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error. > > ``` > > > > This also happens on Boundary's Nitrogen6_soloX board when running the same > > kernel, and likewise with their latest Yocto release that uses 5.4.100 linux-imx kernel. > > > > ``` > > root@nitrogen6sx:~# dd if=/dev/hwrng of=/tmp/random bs=256 count=10 > > [ 113.940735] caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error > > dd: /dev/hwrng: Invalid argument > > root@nitrogen6sx:~# rm /tmp/random > > root@nitrogen6sx:~# dd if=/dev/hwrng of=/tmp/random bs=256 count=10 > > [ 125.300823] caam_jr 2101000.jr0: 20003c5b: CCB: desc idx 60: RNG: Hardware error > > dd: /dev/hwrng: Invalid argument > > root@nitrogen6sx:~# du -hs /tmp/random > > 0 /tmp/random > > root@nitrogen6sx:~# ls -l /tmp/random > > -rw-r--r-- 1 root root 0 Dec 16 17:27 /tmp/random > > root@nitrogen6sx:~# > > ``` > > > > And then no data is available from /dev/hwrng. > > > > The problem occurs when adding OP_ALG_PR_ON(prediction resistance) when setting up > > job descriptor for reading new random data in caamrng.c. There are also > > some confusing parts about this commit that I'm not too sure about. > > > > 1. It's adding a conditional variable named 'pr_support', but I guess this only > > indicates if the MC(Management Complex) supports prediction resistance, > > since the following check can be bypassed when 'pr_support' is false. > > > > /* > > * If SEC has RNG version >= 4 and RNG state handle has not been > > * already instantiated, do RNG instantiation > > * In case of SoCs with Management Complex, RNG is managed by MC f/w. > > */ > > if (!(ctrlpriv->mc_en && pr_support) && rng_vid >= 4) { > > > > > > This will eventually lead to the following chain call: caam_probe() -> instantiate_rng() -> > > build_instantiation_desc(), where OP_ALG_PR_ON will be used through DECO. > > > > static void build_instantiation_desc(u32 *desc, int handle, int do_sk) > > { > > u32 *jump_cmd, op_flags; > > > > init_job_desc(desc, 0); > > > > op_flags = OP_TYPE_CLASS1_ALG | OP_ALG_ALGSEL_RNG | > > (handle << OP_ALG_AAI_SHIFT) | OP_ALG_AS_INIT | > > OP_ALG_PR_ON; > > ... > > ... > > ... > > > > Shouldn't it be named 'mc_pr_support' instead, or something similar? > > > > 2. PR is unconditionally used in caamrng.c(caam_jr module) when > > reading new RNG data. Should this be the case? > > > > Removing OP_ALG_PR_ON in caam_init_desc() from drivers/crypto/caam/caamrng.c > > seems to fix the problem we're experiencing, here's an example: > > ``` > > diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c > > index 77d048dfe5d0..f085a80b1b3c 100644 > > --- a/drivers/crypto/caam/caamrng.c > > +++ b/drivers/crypto/caam/caamrng.c > > @@ -67,8 +67,7 @@ static u32 *caam_init_desc(u32 *desc, dma_addr_t dst_dma) > > { > > init_job_desc(desc, 0); /* + 1 cmd_sz */ > > /* Generate random bytes: + 1 cmd_sz */ > > - append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG | > > - OP_ALG_PR_ON); > > + append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG); > > /* Store bytes: + 1 cmd_sz + caam_ptr_sz */ > > append_fifo_store(desc, dst_dma, > > CAAM_RNG_MAX_FIFO_STORE_SIZE, FIFOST_TYPE_RNGSTORE); > > ``` > > We also observe this issue. > > Heiko on Cc tried increasing the RTSDCTL_ENT_DLY_MIN value > and this seems to help: > > diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h > index af61f3a2c0d4..53c9fa04a24c 100644 > --- a/drivers/crypto/caam/regs.h > +++ b/drivers/crypto/caam/regs.h > @@ -513,7 +513,7 @@ struct rng4tst { > }; > #define RTSDCTL_ENT_DLY_SHIFT 16 > #define RTSDCTL_ENT_DLY_MASK (0xffff << RTSDCTL_ENT_DLY_SHIFT) > -#define RTSDCTL_ENT_DLY_MIN 3200 > +#define RTSDCTL_ENT_DLY_MIN 4800 > #define RTSDCTL_ENT_DLY_MAX 12800 > u32 rtsdctl; /* seed control register */ > union { > > Does this help in your case? > > Thanks, > > Fabio Estevam