Author: sephe
Date: Fri Oct 14 02:36:51 2016
New Revision: 307248
URL: https://svnweb.freebsd.org/changeset/base/307248

Log:
  MFC 306359
  
      pci: Clear the MEM/PORT_EN bit when updating PCI BAR
  
      It's unsafe to update the BAR when the related EN bit is set.
  
      Submitted by:   Dexuan Cui <decui microsoft com>
      Reviewed by:    jhb
      Sponsored by:   Microsoft
      Differential Revision:  https://reviews.freebsd.org/D7914

Modified:
  stable/10/sys/dev/pci/pci.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/dev/pci/pci.c
==============================================================================
--- stable/10/sys/dev/pci/pci.c Fri Oct 14 02:34:03 2016        (r307247)
+++ stable/10/sys/dev/pci/pci.c Fri Oct 14 02:36:51 2016        (r307248)
@@ -4576,6 +4576,7 @@ pci_reserve_map(device_t dev, device_t c
        struct resource_list *rl = &dinfo->resources;
        struct resource *res;
        struct pci_map *pm;
+       uint16_t cmd;
        pci_addr_t map, testval;
        int mapsize;
 
@@ -4660,8 +4661,17 @@ pci_reserve_map(device_t dev, device_t c
                device_printf(child,
                    "Lazy allocation of %#lx bytes rid %#x type %d at %#lx\n",
                    count, *rid, type, rman_get_start(res));
+
+       /* Disable decoding via the CMD register before updating the BAR */
+       cmd = pci_read_config(child, PCIR_COMMAND, 2);
+       pci_write_config(child, PCIR_COMMAND,
+           cmd & ~(PCI_BAR_MEM(map) ? PCIM_CMD_MEMEN : PCIM_CMD_PORTEN), 2);
+
        map = rman_get_start(res);
        pci_write_bar(child, pm, map);
+
+       /* Restore the original value of the CMD register */
+       pci_write_config(child, PCIR_COMMAND, cmd, 2);
 out:
        return (res);
 }
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