arch: Disable priority inheritance on all semaphores used for signaling in all RNG drivers

arch/arm/src/sama5/sam_trng.c

@@ -52,6 +52,7 @@
 
 #include <nuttx/irq.h>
 #include <nuttx/arch.h>
+#include <nuttx/semaphore.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/drivers/drivers.h>
 
@@ -352,9 +353,18 @@ static int sam_rng_initialize(void)
   /* Initialize the device structure */
 
   memset(&g_trngdev, 0, sizeof(struct trng_dev_s));
+
+  /* Initialize semphores */
+
   sem_init(&g_trngdev.exclsem, 0, 1);
   sem_init(&g_trngdev.waitsem, 0, 0);
 
+  /* The waitsem semaphore is used for signaling and, hence, should not have
+   * priority inheritance enabled.
+   */
+
+  sem_setprotocol(&g_trngdev.waitsem, SEM_PRIO_NONE);
+
   /* Enable clocking to the TRNG */
 
   sam_trng_enableclk();

arch/arm/src/samv7/sam_trng.c

@@ -53,6 +53,7 @@
 
 #include <nuttx/irq.h>
 #include <nuttx/arch.h>
+#include <nuttx/semaphore.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/drivers/drivers.h>
 
@@ -353,9 +354,18 @@ static int sam_rng_initialize(void)
   /* Initialize the device structure */
 
   memset(&g_trngdev, 0, sizeof(struct trng_dev_s));
+
+  /* Initialize semaphores */
+
   sem_init(&g_trngdev.exclsem, 0, 1);
   sem_init(&g_trngdev.waitsem, 0, 0);
 
+  /* The waitsem semaphore is used for signaling and, hence, should not have
+   * priority inheritance enabled.
+   */
+
+  sem_setprotocol(&g_trngdev.waitsem, SEM_PRIO_NONE);
+
   /* Enable clocking to the TRNG */
 
   sam_trng_enableclk();

arch/arm/src/stm32l4/stm32l4_rng.c

@@ -47,6 +47,7 @@
 
 #include <nuttx/irq.h>
 #include <nuttx/arch.h>
+#include <nuttx/semaphore.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/drivers/drivers.h>
 
@@ -259,11 +260,14 @@ static ssize_t stm32l4_rngread(struct file *filep, char *buffer, size_t buflen)
     {
       /* We've got the device semaphore, proceed with reading */
 
-      /* Initialize the operation semaphore with 0 for blocking until
-       * the buffer is filled from interrupts.
+      /* Initialize the operation semaphore with 0 for blocking until the
+       * buffer is filled from interrupts.  The waitsem semaphore is used
+       * for signaling and, hence, should not have priority inheritance
+       * enabled.
        */
 
       sem_init(&g_rngdev.rd_readsem, 0, 0);
+      sem_setprotocol(&g_rngdev.rd_readsem, SEM_PRIO_NONE);
 
       g_rngdev.rd_buflen = buflen;
       g_rngdev.rd_buf = buffer;