ssb: add delay after PCI reset to fix SoC reboots

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/ssb/driver_pcicore.c b/drivers/ssb/driver_pcicore.c
index d75b72ba2672..15a7ee3859dd 100644
--- a/drivers/ssb/driver_pcicore.c
+++ b/drivers/ssb/driver_pcicore.c
@@ -357,6 +357,15 @@ static void ssb_pcicore_init_hostmode(struct ssb_pcicore *pc)
         pcicore_write32(pc, SSB_PCICORE_SBTOPCI2,
                         SSB_PCICORE_SBTOPCI_MEM | SSB_PCI_DMA);
 
+        /*
+         * Accessing PCI config without a proper delay after devices reset (not
+         * GPIO reset) was causing reboots on WRT300N v1.0.
+         * Tested delay 850 us lowered reboot chance to 50-80%, 1000 us fixed it
+         * completely. Flushing all writes was also tested but with no luck.
+         */
+        if (pc->dev->bus->chip_id == 0x4704)
+                usleep_range(1000, 2000);
+
         /* Enable PCI bridge BAR0 prefetch and burst */
         val = PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY;
         ssb_extpci_write_config(pc, 0, 0, 0, PCI_COMMAND, &val, 2);