Re: [PATCH V3 1/2] pseries/eeh: Handle RTAS delay requests in configure_bridge

2016-04-07 Thread Gavin Shan 
On Thu, Apr 07, 2016 at 04:28:26PM +1000, Russell Currey wrote:
>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:  # 3.10+
>Signed-off-by: Russell Currey 

Acked-by: Gavin Shan 

>---
>V3 changelog:
> - Refactorings and rewordings thanks to Gavin
> - Treat return values >9902 as 9902 thanks to Tyrel
>---
> arch/powerpc/platforms/pseries/eeh_pseries.c | 51 
> 1 file changed, 36 insertions(+), 15 deletions(-)
>
>diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c 
>b/arch/powerpc/platforms/pseries/eeh_pseries.c
>index ac3ffd9..405baaf 100644
>--- 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;
> }
> 
>-- 
>2.8.0
>
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[PATCH V3 1/2] pseries/eeh: Handle RTAS delay requests in configure_bridge

2016-04-07 Thread Russell Currey 
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:  # 3.10+
Signed-off-by: Russell Currey 
---
V3 changelog:
 - Refactorings and rewordings thanks to Gavin
 - Treat return values >9902 as 9902 thanks to Tyrel
---
 arch/powerpc/platforms/pseries/eeh_pseries.c | 51 
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c 
b/arch/powerpc/platforms/pseries/eeh_pseries.c
index ac3ffd9..405baaf 100644
--- 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;
 }
 
-- 
2.8.0

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