powerpc/pseries/eeh: Handle RTAS delay requests in configure_bridge

In the "ibm,configure-pe" and "ibm,configure-bridge" RTAS calls, the
spec states that values of 9900-9905 can be returned, indicating that
software should delay for 10^x (where x is the last digit, i.e. 990x)
milliseconds and attempt the call again. Currently, the kernel doesn't
know about this, and respecting it fixes some PCI failures when the
hypervisor is busy.

The delay is capped at 0.2 seconds.

Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: Russell Currey <ruscur@russell.cc>
Acked-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index ac3ffd97e0596626a1c72c930d76ac994c683b82..405baaf9686416074bb5445854edb7d5e62776b4 100644 (file)
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -615,29 +615,50 @@ static int pseries_eeh_configure_bridge(struct eeh_pe *pe)
 {
        int config_addr;
        int ret;
+       /* Waiting 0.2s maximum before skipping configuration */
+       int max_wait = 200;
 
        /* Figure out the PE address */
        config_addr = pe->config_addr;
        if (pe->addr)
                config_addr = pe->addr;
 
-       /* Use new configure-pe function, if supported */
-       if (ibm_configure_pe != RTAS_UNKNOWN_SERVICE) {
-               ret = rtas_call(ibm_configure_pe, 3, 1, NULL,
-                               config_addr, BUID_HI(pe->phb->buid),
-                               BUID_LO(pe->phb->buid));
-       } else if (ibm_configure_bridge != RTAS_UNKNOWN_SERVICE) {
-               ret = rtas_call(ibm_configure_bridge, 3, 1, NULL,
-                               config_addr, BUID_HI(pe->phb->buid),
-                               BUID_LO(pe->phb->buid));
-       } else {
-               return -EFAULT;
-       }
+       while (max_wait > 0) {
+               /* Use new configure-pe function, if supported */
+               if (ibm_configure_pe != RTAS_UNKNOWN_SERVICE) {
+                       ret = rtas_call(ibm_configure_pe, 3, 1, NULL,
+                                       config_addr, BUID_HI(pe->phb->buid),
+                                       BUID_LO(pe->phb->buid));
+               } else if (ibm_configure_bridge != RTAS_UNKNOWN_SERVICE) {
+                       ret = rtas_call(ibm_configure_bridge, 3, 1, NULL,
+                                       config_addr, BUID_HI(pe->phb->buid),
+                                       BUID_LO(pe->phb->buid));
+               } else {
+                       return -EFAULT;
+               }
 
-       if (ret)
-               pr_warn("%s: Unable to configure bridge PHB#%d-PE#%x (%d)\n",
-                       __func__, pe->phb->global_number, pe->addr, ret);
+               if (!ret)
+                       return ret;
+
+               /*
+                * If RTAS returns a delay value that's above 100ms, cut it
+                * down to 100ms in case firmware made a mistake.  For more
+                * on how these delay values work see rtas_busy_delay_time
+                */
+               if (ret > RTAS_EXTENDED_DELAY_MIN+2 &&
+                   ret <= RTAS_EXTENDED_DELAY_MAX)
+                       ret = RTAS_EXTENDED_DELAY_MIN+2;
+
+               max_wait -= rtas_busy_delay_time(ret);
+
+               if (max_wait < 0)
+                       break;
+
+               rtas_busy_delay(ret);
+       }
 
+       pr_warn("%s: Unable to configure bridge PHB#%d-PE#%x (%d)\n",
+               __func__, pe->phb->global_number, pe->addr, ret);
        return ret;
 }