Re: [PATCH V2 05/19] irqchip: crossbar: Change allocation logic by reversing search for free irqs

2014-06-13 Thread Sricharan R 
Hi Jason,

On Thursday 12 June 2014 06:26 PM, Jason Cooper wrote:
 On Thu, Jun 12, 2014 at 05:23:13PM +0530, Sricharan R wrote:
 From: Nishanth Menon n...@ti.com

 Reverse the search algorithm to ensure that address mapping and IRQ
 allocation logics are proper. This can open up new bugs which are
 easily fixable rather than wait till allocation logic approaches
 the limit to find new bugs.
 
 Could you expand on this logic some more?  What class of bugs are you
 hoping to discover more easily?
 

class 1. address space errors - example:
reg = a size_b
ti,max-irqs =  is a wrong parameter

class 2: irq-reserved list - which decides which entries in the
address space is not actually wired in

class 3: wrong list of routable-irqs.

in general allocating from max to min tends to have benefits in
ensuring the different issues that may be present in dts is easily
caught at definition time, rather than at a later point in time.


Regards,
 Sricharan
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Re: [PATCH V2 05/19] irqchip: crossbar: Change allocation logic by reversing search for free irqs

2014-06-13 Thread Jason Cooper 
On Fri, Jun 13, 2014 at 11:39:39AM +0530, Sricharan R wrote:
 Hi Jason,
 
 On Thursday 12 June 2014 06:26 PM, Jason Cooper wrote:
  On Thu, Jun 12, 2014 at 05:23:13PM +0530, Sricharan R wrote:
  From: Nishanth Menon n...@ti.com
 
  Reverse the search algorithm to ensure that address mapping and IRQ
  allocation logics are proper. This can open up new bugs which are
  easily fixable rather than wait till allocation logic approaches
  the limit to find new bugs.
  
  Could you expand on this logic some more?  What class of bugs are you
  hoping to discover more easily?
  
 
 class 1. address space errors - example:
 reg = a size_b
 ti,max-irqs =  is a wrong parameter
 
 class 2: irq-reserved list - which decides which entries in the
 address space is not actually wired in
 
 class 3: wrong list of routable-irqs.
 
 in general allocating from max to min tends to have benefits in
 ensuring the different issues that may be present in dts is easily
 caught at definition time, rather than at a later point in time.

Perfect, thanks for clarifying.  Please add this to the commit log when
you respin.

thx,

Jason.
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[PATCH V2 05/19] irqchip: crossbar: Change allocation logic by reversing search for free irqs

2014-06-12 Thread Sricharan R 
From: Nishanth Menon n...@ti.com

Reverse the search algorithm to ensure that address mapping and IRQ
allocation logics are proper. This can open up new bugs which are
easily fixable rather than wait till allocation logic approaches
the limit to find new bugs.

Signed-off-by: Nishanth Menon n...@ti.com
Signed-off-by: Sricharan R r.sricha...@ti.com
Signed-off-by: Tony Lindgren t...@atomide.com
---
 drivers/irqchip/irq-crossbar.c |4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-crossbar.c b/drivers/irqchip/irq-crossbar.c
index 287d3ce..de021638 100644
--- a/drivers/irqchip/irq-crossbar.c
+++ b/drivers/irqchip/irq-crossbar.c
@@ -68,7 +68,7 @@ static inline int get_prev_map_irq(int cb_no)
 {
int i;
 
-   for (i = 0; i  cb-int_max; i++)
+   for (i = cb-int_max - 1; i = 0; i--)
if (cb-irq_map[i] == cb_no)
return i;
 
@@ -79,7 +79,7 @@ static inline int allocate_free_irq(int cb_no)
 {
int i;
 
-   for (i = 0; i  cb-int_max; i++) {
+   for (i = cb-int_max - 1; i = 0; i--) {
if (cb-irq_map[i] == IRQ_FREE) {
cb-irq_map[i] = cb_no;
return i;
-- 
1.7.9.5

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Re: [PATCH V2 05/19] irqchip: crossbar: Change allocation logic by reversing search for free irqs

2014-06-12 Thread Jason Cooper 
On Thu, Jun 12, 2014 at 05:23:13PM +0530, Sricharan R wrote:
 From: Nishanth Menon n...@ti.com
 
 Reverse the search algorithm to ensure that address mapping and IRQ
 allocation logics are proper. This can open up new bugs which are
 easily fixable rather than wait till allocation logic approaches
 the limit to find new bugs.

Could you expand on this logic some more?  What class of bugs are you
hoping to discover more easily?

thx,

Jason.

 Signed-off-by: Nishanth Menon n...@ti.com
 Signed-off-by: Sricharan R r.sricha...@ti.com
 Signed-off-by: Tony Lindgren t...@atomide.com
 ---
  drivers/irqchip/irq-crossbar.c |4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)
 
 diff --git a/drivers/irqchip/irq-crossbar.c b/drivers/irqchip/irq-crossbar.c
 index 287d3ce..de021638 100644
 --- a/drivers/irqchip/irq-crossbar.c
 +++ b/drivers/irqchip/irq-crossbar.c
 @@ -68,7 +68,7 @@ static inline int get_prev_map_irq(int cb_no)
  {
   int i;
  
 - for (i = 0; i  cb-int_max; i++)
 + for (i = cb-int_max - 1; i = 0; i--)
   if (cb-irq_map[i] == cb_no)
   return i;
  
 @@ -79,7 +79,7 @@ static inline int allocate_free_irq(int cb_no)
  {
   int i;
  
 - for (i = 0; i  cb-int_max; i++) {
 + for (i = cb-int_max - 1; i = 0; i--) {
   if (cb-irq_map[i] == IRQ_FREE) {
   cb-irq_map[i] = cb_no;
   return i;
 -- 
 1.7.9.5
 
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