Cortex-M7: Add support for enabled the D-Cache in write only mode.

SAMV7 Ethernet:  I- and D-Cache are now enabled in the netnsh/ configuration.  D-Cache is enabled in write-though mode.  This mode is necessary because the DMA descriptors are each 8-bytes in size but the D-Cache cache line is 32-bits in size. So it is impossible make coherency for every 8-byte DMA descriptor without write-through.

4 files changed, 20 insertions, 24 deletions

diff --git a/apps/nshlib/nsh_fscmds.c b/apps/nshlib/nsh_fscmds.c
index 570ffa776..3900fc64a 100644
--- a/apps/nshlib/nsh_fscmds.c
+++ b/apps/nshlib/nsh_fscmds.c
@@ -390,7 +390,7 @@ static int ls_recursive(FAR struct nsh_vtbl_s *vtbl, const char *dirpath,
     {
       /* Yes.. */
 
-      char *newpath;
+      FAR char *newpath;
       newpath = nsh_getdirpath(dirpath, entryp->d_name);
 
       /* List the directory contents */
@@ -408,6 +408,7 @@ static int ls_recursive(FAR struct nsh_vtbl_s *vtbl, const char *dirpath,
           free(newpath);
         }
     }
+
   return ret;
 }
 
diff --git a/nuttx/arch/arm/src/samv7/Kconfig b/nuttx/arch/arm/src/samv7/Kconfig
index 41e40b5df..08d8f7570 100644
--- a/nuttx/arch/arm/src/samv7/Kconfig
+++ b/nuttx/arch/arm/src/samv7/Kconfig
@@ -120,10 +120,10 @@ config SAMV7_EMAC
 	select ARMV7M_DCACHE_WRITETHROUGH if ARMV7M_DCACHE
 	---help---
 		NOTE that write-through caching is automatically selected.  This is
-		to work around issues with the RX and TX descriptors with are 8-bits
+		to work around issues with the RX and TX descriptors with are 8-bytes
 		in size.  But the D-Cache cache line size is 32-bytes.  That means
 		that you cannot reload, clean or invalidate a descriptor without also
-		effecting three neighboring desciptors.  Setting write through mode
+		effecting three neighboring descriptors.  Setting write through mode
 		eliminates the need for cleaning.  If only reloading and invalidating
 		are done, then there is no problem.
 
diff --git a/nuttx/configs/samv71-xult/README.txt b/nuttx/configs/samv71-xult/README.txt
index 0efaff880..f242c1faa 100644
--- a/nuttx/configs/samv71-xult/README.txt
+++ b/nuttx/configs/samv71-xult/README.txt
@@ -88,28 +88,21 @@ The BASIC nsh configuration is fully function (as desribed below under
      So there is still plenty to be done.
 
   6. There is a port of the SAMA5D4-EK Ethernet driver to the SAMV71-XULT.
-     Some basic functionality is present, but there is at least two,
-     probably related issues:
+     This driver appears to be 100% functional with the following caveats:
 
      - There is a compiler optimization problem.  At -O2, there is odd
        behavior on pings and ARP messages.  But the behavior is OK with
-       optimization disabled.  This may or may not be a compiler issue; it
-       may be a timing issue.
-
-       Symptoms vary from build to build but usually result in a hang.
-
-     - The driver does not work with I- and D-Caches enabled.  The behavior
-       is just as for when compiler optimization is enabled.  I have not
-       yet found in coherency issues so this might also be timing related.
-
-       At -O2, many packets can be exchanged but eventually there is a
-       hardfault, presumably because of a misdirected DMA.
-
-     I have no hard evidence, but I believe that the nature of the problem
-     related to fact that each descriptor in the arrays are 8-bytes each,
-     but cache operations are performed on 32-byte memory chunks.  So it is
-     impossible to clean or invalidate a single descriptor without also
-     cleaning or invalidaing adjacent descriptors.
+       optimization set to -O2.  This may or may not be a compiler
+       optimization issue (it could also be a timing issue or a need
+       for some additional volatile qualifiers).
+
+     - I- and D-Caches are enabled but the D-Cache must be enabled in
+       write-trough mode.  This is to work around issues with the RX and TX
+       descriptors with are 8-bytes in size.  But the D-Cache cache line size
+       is 32-bytes.  That means that you cannot reload, clean or invalidate a
+       descriptor without also effecting three neighboring descriptors.
+       Setting write through mode eliminates the need for cleaning the D-Cache.
+       If only reloading and invalidating are done, then there is no problem.
 
   7. The USBHS device controller driver (DCD) is complete but non-functional.
      At this point, work has stopped because I am stuck.  The problem is that
diff --git a/nuttx/configs/samv71-xult/netnsh/defconfig b/nuttx/configs/samv71-xult/netnsh/defconfig
index e74dd1913..989aad989 100644
--- a/nuttx/configs/samv71-xult/netnsh/defconfig
+++ b/nuttx/configs/samv71-xult/netnsh/defconfig
@@ -122,8 +122,9 @@ CONFIG_ARCH_DPFPU=y
 #
 CONFIG_ARMV7M_HAVE_ICACHE=y
 CONFIG_ARMV7M_HAVE_DCACHE=y
-# CONFIG_ARMV7M_ICACHE is not set
-# CONFIG_ARMV7M_DCACHE is not set
+CONFIG_ARMV7M_ICACHE=y
+CONFIG_ARMV7M_DCACHE=y
+CONFIG_ARMV7M_DCACHE_WRITETHROUGH=y
 CONFIG_ARMV7M_HAVE_ITCM=y
 CONFIG_ARMV7M_HAVE_DTCM=y
 # CONFIG_ARMV7M_ITCM is not set
@@ -572,6 +573,7 @@ CONFIG_ETH0_PHY_KSZ8061=y
 # CONFIG_ETH0_PHY_DP83848C is not set
 # CONFIG_ETH0_PHY_LAN8720 is not set
 # CONFIG_ETH0_PHY_LAN8740 is not set
+# CONFIG_ETH0_PHY_LAN8740A is not set
 # CONFIG_ETH0_PHY_DM9161 is not set
 # CONFIG_PIPES is not set
 # CONFIG_PM is not set