[PATCH] powerpc/powernv: Call opal_pci_poll() if needed

[PATCH] powerpc/powernv: Call opal_pci_poll() if needed

[Gavin Shan]

When issuing PHB reset, OPAL API opal_pci_poll() is called to drive
the state machine in OPAL forward. However, we needn't always call
the function under some circumstances like reset deassert.

This avoids calling opal_pci_poll() when OPAL_SUCCESS is returned
from opal_pci_reset(). Except the overhead introduced by additional
one unnecessary OPAL call, I didn't run into real issue because of
this.

Reported-by: Pridhiviraj Paidipeddi <ppaiddipe@in.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/eeh-powernv.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c b/arch/powerpc/platforms/powernv/eeh-powernv.c
index 86544ea..931b305 100644
--- a/arch/powerpc/platforms/powernv/eeh-powernv.c
+++ b/arch/powerpc/platforms/powernv/eeh-powernv.c
@@ -763,7 +763,8 @@ int pnv_eeh_phb_reset(struct pci_controller *hose, int option)
 	 * reset followed by hot reset on root bus. So we also
 	 * need the PCI bus settlement delay.
 	 */
-	rc = pnv_eeh_poll(phb->opal_id);
+	if (rc > 0)
+		rc = pnv_eeh_poll(phb->opal_id);
 	if (option == EEH_RESET_DEACTIVATE) {
 		if (system_state < SYSTEM_RUNNING)
 			udelay(1000 * EEH_PE_RST_SETTLE_TIME);
@@ -806,7 +807,8 @@ static int pnv_eeh_root_reset(struct pci_controller *hose, int option)
 		goto out;
 
 	/* Poll state of the PHB until the request is done */
-	rc = pnv_eeh_poll(phb->opal_id);
+	if (rc > 0)
+		rc = pnv_eeh_poll(phb->opal_id);
 	if (option == EEH_RESET_DEACTIVATE)
 		msleep(EEH_PE_RST_SETTLE_TIME);
 out:
-- 
2.1.0

Re: powerpc/powernv: Call opal_pci_poll() if needed

[Michael Ellerman]

On Fri, 2016-24-06 at 06:44:19 UTC, Gavin Shan wrote:
> When issuing PHB reset, OPAL API opal_pci_poll() is called to drive
> the state machine in OPAL forward. However, we needn't always call
> the function under some circumstances like reset deassert.
> 
> This avoids calling opal_pci_poll() when OPAL_SUCCESS is returned
> from opal_pci_reset(). Except the overhead introduced by additional
> one unnecessary OPAL call, I didn't run into real issue because of
> this.
> 
> Reported-by: Pridhiviraj Paidipeddi <ppaiddipe@in.ibm.com>
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/fbce44d0ed42e4653172376f4dfeaa

cheers