From 6abdd33a088db9bca9fd79ab6ebe5e5c17fb68b1 Mon Sep 17 00:00:00 2001 From: Aleksander Jan Bajkowski Date: Mon, 5 Jan 2026 21:41:49 +0100 Subject: [PATCH] hwrng: airoha - set rng quality to 900 [ Upstream commit c0008a29a006091d7f9d288620c2456afa23ff27 ] Airoha uses RAW mode to collect noise from the TRNG. These appear to be unprocessed oscillations from the tero loop. For this reason, they do not have a perfect distribution and entropy. Simple noise compression reduces its size by 9%, so setting the quality to 900 seems reasonable. The same value is used by the downstream driver. Compare the size before and after compression: $ ls -l random_airoha* -rw-r--r-- 1 aleksander aleksander 76546048 Jan 3 23:43 random_airoha -rw-rw-r-- 1 aleksander aleksander 69783562 Jan 5 20:23 random_airoha.zip FIPS test results: $ cat random_airoha | rngtest -c 10000 rngtest 2.6 Copyright (c) 2004 by Henrique de Moraes Holschuh This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. rngtest: starting FIPS tests... rngtest: bits received from input: 200000032 rngtest: FIPS 140-2 successes: 0 rngtest: FIPS 140-2 failures: 10000 rngtest: FIPS 140-2(2001-10-10) Monobit: 9957 rngtest: FIPS 140-2(2001-10-10) Poker: 10000 rngtest: FIPS 140-2(2001-10-10) Runs: 10000 rngtest: FIPS 140-2(2001-10-10) Long run: 4249 rngtest: FIPS 140-2(2001-10-10) Continuous run: 0 rngtest: input channel speed: (min=953.674; avg=27698.935; max=19073.486)Mibits/s rngtest: FIPS tests speed: (min=59.791; avg=298.028; max=328.853)Mibits/s rngtest: Program run time: 647638 microseconds In general, these data look like real noise, but with lower entropy than expected. Fixes: e53ca8efcc5e ("hwrng: airoha - add support for Airoha EN7581 TRNG") Suggested-by: Benjamin Larsson Signed-off-by: Aleksander Jan Bajkowski Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin --- drivers/char/hw_random/airoha-trng.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/char/hw_random/airoha-trng.c b/drivers/char/hw_random/airoha-trng.c index 1dbfa9505c21..9a648f6d9fd4 100644 --- a/drivers/char/hw_random/airoha-trng.c +++ b/drivers/char/hw_random/airoha-trng.c @@ -212,6 +212,7 @@ static int airoha_trng_probe(struct platform_device *pdev) trng->rng.init = airoha_trng_init; trng->rng.cleanup = airoha_trng_cleanup; trng->rng.read = airoha_trng_read; + trng->rng.quality = 900; ret = devm_hwrng_register(dev, &trng->rng); if (ret) {