psa_crypto_rsa: add comment/explanation for residual PK_WRITE_C guard
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/psa_crypto_rsa.c b/library/psa_crypto_rsa.c
index 6e90f1c..0db425f 100644
--- a/library/psa_crypto_rsa.c
+++ b/library/psa_crypto_rsa.c
@@ -172,6 +172,9 @@
size_t data_size,
size_t *data_length)
{
+/* Currently this is always true due to the fact that build_info.h auto-enables
+ * MBEDTLS_PK_WRITE_C whenever both PSA and RSA_C are enabled.
+ * However we keep the guard here to emphasize this dependency explicitly. */
#if defined(MBEDTLS_PK_WRITE_C)
int ret;
mbedtls_pk_context pk;