From c0008a29a006091d7f9d288620c2456afa23ff27 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 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 --- 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 1dbfa9505c214..9a648f6d9fd40 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) { -- 2.47.3