Re: [PATCH] of/irq: fix bug in computing output requester-id for an msi-map

From: David Daney
Date: Mon Feb 08 2016 - 18:47:57 EST


On 02/08/2016 02:30 PM, Stuart Yoder wrote:
From: Stuart Yoder <stuart.yoder@xxxxxxx>

The binding for msi-map specifies that the output requester id
should be computed as: (r - rid-base + msi-base)

...update the code accordingly.

I agree there is a problem however ...


Signed-off-by: Stuart Yoder <stuart.yoder@xxxxxxx>
---
drivers/of/irq.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 706e3ff..3f5e5fd 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -589,6 +589,7 @@ static u32 __of_msi_map_rid(struct device *dev, struct device_node **np,
struct device_node *msi_controller_node;
struct device_node *msi_np = *np;
u32 map_mask, masked_rid, rid_base, msi_base, rid_len, phandle;
+ u32 masked_rid_base;
int msi_map_len;
bool matched;
u32 rid_out = rid_in;
@@ -654,7 +655,8 @@ static u32 __of_msi_map_rid(struct device *dev, struct device_node **np,
if (!matched)
return rid_out;

- rid_out = masked_rid + msi_base;
+ masked_rid_base = map_mask & rid_base;

... The binding document nowhere, that I see, talks about applying the mask to the rid-base.

The device tree should already contain the rid-base in the correct range.

If you remove this masking step, I think it may be correct.

If you just do:

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 7ee21ae..92abe01 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -654,7 +654,7 @@ static u32 __of_msi_map_rid(struct device *dev, struct device_node **np,
if (!matched)
return rid_out;

- rid_out = masked_rid + msi_base;
+ rid_out = msi_base + (masked_rid - rid_base);
dev_dbg(dev,
"msi-map at: %s, using mask %08x, rid-base: %08x, msi-base: %08x, length: %08x, rid: %08x -> %08x\n",

It think it will be correct.

I have tested it that way. If you do that,

Acked-by: David Daney <david.daney@xxxxxxxxxx>

+ rid_out = msi_base + (masked_rid - masked_rid_base);
dev_dbg(dev,
"msi-map at: %s, using mask %08x, rid-base: %08x, msi-base: %08x, length: %08x, rid: %08x -> %08x\n",
dev_name(parent_dev), map_mask, rid_base, msi_base,