svn commit: r272239 - head/sys/mips/atheros

[Adrian Chadd]

Author: adrian
Date: Sun Sep 28 07:27:58 2014
New Revision: 272239
URL: http://svnweb.freebsd.org/changeset/base/272239

Log:
  Fix the AR724x PCIe glue to correctly probe the BAR on AR7240 devices.
  
  There's a bug in the AR7240 PCIe hardware where a correct BAR will end
  up having the device disappear.
  
  It turns out that for the device address it should be all 0's.
  
  However, this meant that the PCI probe code would try writing 0xffffffff
  in to see how big the window was, read back 0x0, and think the window
  was 32 bits.  It then ended up calculating a resource size of 0 bytes,
  failed to find anything via an rman call, and this would fail to attach.
  
  I have quite absolutely no idea how in the various planes of existence
  this particular bit of code and how it worked with the PCI bus code
  ever worked.  But, well, it did.
  
  Tested:
  
  * Atheros AP93 - AR7240 + AR9280 reference board

Modified:
  head/sys/mips/atheros/ar724x_pci.c

Modified: head/sys/mips/atheros/ar724x_pci.c
==============================================================================
--- head/sys/mips/atheros/ar724x_pci.c	Sun Sep 28 07:19:32 2014	(r272238)
+++ head/sys/mips/atheros/ar724x_pci.c	Sun Sep 28 07:27:58 2014	(r272239)
@@ -159,10 +159,18 @@ ar724x_pci_write_config(device_t dev, u_
 		return;
 
 	/*
-	 * WAR for BAR issue on AR7240 - We are unable to access the PCI device
-	 * space if we set the BAR with proper base address.
+	 * WAR for BAR issue on AR7240 - We are unable to access the PCI
+	 * device space if we set the BAR with proper base address.
+	 *
+	 * However, we _do_ want to allow programming in the probe value
+	 * (0xffffffff) so the PCI code can find out how big the memory
+	 * map is for this device.  Without it, it'll think the memory
+	 * map is 32 bits wide, the PCI code will then end up thinking
+	 * the register window is '0' and fail to allocate resources.
 	 */
-	if (reg == PCIR_BAR(0) && bytes == 4 && ar71xx_soc == AR71XX_SOC_AR7240)
+	if (reg == PCIR_BAR(0) && bytes == 4
+	    && ar71xx_soc == AR71XX_SOC_AR7240
+	    && data != 0xffffffff)
 		ar724x_pci_write(AR724X_PCI_CFG_BASE, reg, 0xffff, bytes);
 	else
 		ar724x_pci_write(AR724X_PCI_CFG_BASE, reg, data, bytes);