[PATCH] powerpc/pci: Fix PHB numbering when using opal-phbid

[PATCH] powerpc/pci: Fix PHB numbering when using opal-phbid

[Michael Ellerman]

The recent change to the PHB numbering logic has a logic error in the
handling of "ibm,opal-phbid".

When an "ibm,opal-phbid" property is present, &prop is written to and
ret is set to zero.

The following call to of_alias_get_id() is skipped because ret == 0.

But then the if (ret >= 0) is true, and the body of that if statement
sets prop = ret which throws away the value that was just read from
"ibm,opal-phbid".

Fix the logic by only doing the ret >= 0 check in the of_alias_get_id()
case.

Fixes: 0fe1e96fef0a ("powerpc/pci: Prefer PCI domain assignment via DT 'linux,pci-domain' and alias")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/kernel/pci-common.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 8ce36aba42da..bdd3332200c5 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -91,11 +91,13 @@ static int get_phb_number(struct device_node *dn)
 	}
 	if (ret)
 		ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop);
-	if (ret)
+
+	if (ret) {
 		ret = of_alias_get_id(dn, "pci");
-	if (ret >= 0) {
-		prop = ret;
-		ret = 0;
+		if (ret >= 0) {
+			prop = ret;
+			ret = 0;
+		}
 	}
 	if (ret) {
 		u32 prop_32;
-- 
2.35.3

Re: [PATCH] powerpc/pci: Fix PHB numbering when using opal-phbid

[Pali Rohár]

On Tuesday 02 August 2022 20:57:23 Michael Ellerman wrote:
> The recent change to the PHB numbering logic has a logic error in the
> handling of "ibm,opal-phbid".
> 
> When an "ibm,opal-phbid" property is present, &prop is written to and
> ret is set to zero.
> 
> The following call to of_alias_get_id() is skipped because ret == 0.
> 
> But then the if (ret >= 0) is true, and the body of that if statement
> sets prop = ret which throws away the value that was just read from
> "ibm,opal-phbid".

Now I see, I wrote logic incorrectly.

> Fix the logic by only doing the ret >= 0 check in the of_alias_get_id()
> case.
> 
> Fixes: 0fe1e96fef0a ("powerpc/pci: Prefer PCI domain assignment via DT 'linux,pci-domain' and alias")
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Your change should fix this issue, so:

Reviewed-by: Pali Rohár <pali@kernel.org>

> ---
>  arch/powerpc/kernel/pci-common.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index 8ce36aba42da..bdd3332200c5 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -91,11 +91,13 @@ static int get_phb_number(struct device_node *dn)
>  	}
>  	if (ret)
>  		ret = of_property_read_u64(dn, "ibm,opal-phbid", &prop);
> -	if (ret)
> +
> +	if (ret) {
>  		ret = of_alias_get_id(dn, "pci");
> -	if (ret >= 0) {
> -		prop = ret;
> -		ret = 0;
> +		if (ret >= 0) {
> +			prop = ret;
> +			ret = 0;
> +		}
>  	}
>  	if (ret) {
>  		u32 prop_32;
> -- 
> 2.35.3
> 

Re: [PATCH] powerpc/pci: Fix PHB numbering when using opal-phbid

[Michael Ellerman]

On Tue, 2 Aug 2022 20:57:23 +1000, Michael Ellerman wrote:
> The recent change to the PHB numbering logic has a logic error in the
> handling of "ibm,opal-phbid".
> 
> When an "ibm,opal-phbid" property is present, &prop is written to and
> ret is set to zero.
> 
> The following call to of_alias_get_id() is skipped because ret == 0.
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/pci: Fix PHB numbering when using opal-phbid
      https://git.kernel.org/powerpc/c/f4b39e88b42d13366b831270306326b5c20971ca

cheers