svn commit: r331132 - head/sys/dev/flash

[Ian Lepore]

Author: ian
Date: Sun Mar 18 16:52:31 2018
New Revision: 331132
URL: https://svnweb.freebsd.org/changeset/base/331132

Log:
  Bugfix: wait for writes/erases to complete after starting them, instead of
  before starting them.
  
  Using the wait-before logic would make sense if there was useful time-
  consuming work that could be done between the end of one write and the
  beginning of the next, but it also requires doing the wait-for-ready before
  reading, because a prior write or erase could still be in progress.  Reading
  is the far more common case, so adding a whole extra bus transaction to
  check for ready before each read would soak up any small gains that might be
  had from doing async writes.

Modified:
  head/sys/dev/flash/mx25l.c

Modified: head/sys/dev/flash/mx25l.c
==============================================================================
--- head/sys/dev/flash/mx25l.c	Sun Mar 18 16:49:30 2018	(r331131)
+++ head/sys/dev/flash/mx25l.c	Sun Mar 18 16:52:31 2018	(r331132)
@@ -247,7 +247,6 @@ mx25l_erase_cmd(device_t dev, off_t sector, uint8_t ec
 
 	sc = device_get_softc(dev);
 
-	mx25l_wait_for_device_ready(dev);
 	mx25l_set_writable(dev, 1);
 
 	memset(&cmd, 0, sizeof(cmd));
@@ -272,6 +271,7 @@ mx25l_erase_cmd(device_t dev, off_t sector, uint8_t ec
 		txBuf[3] = (sector & 0xff);
 	}
 	err = SPIBUS_TRANSFER(device_get_parent(dev), dev, &cmd);
+	mx25l_wait_for_device_ready(dev);
 }
 
 static int
@@ -339,6 +339,7 @@ mx25l_write(device_t dev, off_t offset, caddr_t data, 
 		mx25l_set_writable(dev, 1);
 
 		err = SPIBUS_TRANSFER(pdev, dev, &cmd);
+		mx25l_wait_for_device_ready(dev);
 		if (err)
 			break;