drivers/mmcsd/Kconfig|mmcsd_sdio.c: check ready without sleep

If per tick is set to 10ms, it will cause nxsig_usleep(1000) in the
sdio driver to sleep for 19ms, which is much longer than the
expected 1ms, resulting in very low write performance. Add option to
reduce CPU hogging by using sched_yield(), though it may also affect
write performance when the CPU is busy.

Signed-off-by: Yinzhe Wu <Yinzhe.Wu@sony.com>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Jacky Cao <Jacky.Cao@sony.com>
Tested-by: Yinzhe Wu <Yinzhe.Wu@sony.com>

Author: Windrow14

drivers/mmcsd/Kconfig

@@ -177,6 +177,19 @@ config MMCSD_BLOCK_WDATADELAY
 		Some hardware needs to configure this delay to write one data block, because
 		the hardware needs more time for wear leveling and bad block management.
 
+config MMCSD_CHECK_READY_STATUS_WITHOUT_SLEEP
+	bool "No sleep in ready-check function."
+	default n
+	---help---
+		Since nxsig_usleep returns at the tick after the next tick, when
+		CONFIG_USEC_PER_TICK is big, the real sleep time is much more than
+		desired in mmcsd_transferready(). As a result, write speed is
+		affected seriously.
+
+		When this configuration is enabled, the sleep in mmcsd_transferready
+		will be skipped. However, CPU will be hogged by the process during
+		this period of writing time.
+
 endif
 
 endif # MMCSD

drivers/mmcsd/mmcsd_sdio.c

@@ -1251,7 +1251,13 @@ static int mmcsd_transferready(FAR struct mmcsd_state_s *priv)
 
       /* Do not hog the CPU */
 
+#ifdef CONFIG_MMCSD_CHECK_READY_STATUS_WITHOUT_SLEEP
+      /* Use sched_yield when tick is big to avoid low writing speed */
+
+      sched_yield();
+#else
       nxsig_usleep(1000);
+#endif
 
       /* We are still in the programming state. Calculate the elapsed
        * time... we can't stay in this loop forever!