Re: [PATCH 2/2] fsl_ifc: Support all 8 IFC chip selects

On Wed, 2014-08-20 at 09:05 +0530, Prabhakar Kushwaha wrote:

On 8/20/2014 5:38 AM, Scott Wood wrote:

quoted

On Fri, 2014-08-15 at 16:07 -0500, Aaron Sierra wrote:

quoted

Freescale's QorIQ T Series processors support 8 IFC chip selects
within a memory map backward compatible with previous P Series
processors which supported only 4 chip selects.

Signed-off-by: Aaron Sierra <redacted>
---
  include/linux/fsl_ifc.h | 10 +++++-----
  1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/fsl_ifc.h b/include/linux/fsl_ifc.h
index 84d60cb..62762ff 100644
--- a/include/linux/fsl_ifc.h
+++ b/include/linux/fsl_ifc.h

@@ -29,7 +29,7 @@
  #include <linux/of_platform.h>
  #include <linux/interrupt.h>
  
-#define FSL_IFC_BANK_COUNT 4
+#define FSL_IFC_BANK_COUNT 8

First please modify fsl_ifc_nand.c to limit itself to the number of
banks it dynamically determines are present based on the IFC version.

Number of available bank/chip select are defined by SoC and it is 
independent of SoC.

Do you mean defined by the SoC and independent of the IFC version?

It should be fix in following way

Option 1:
u-boot:  fix device tree with number of available chip select. It may 
require IFC binding change
Linux: Read device tree and determine the Chip Selects

If we do this then it will need to be an optional property that defaults
to the current assumption being made (4).

In the future we really ought to check whether there are integration
parameters when coming up with the initial binding for a hardware
block...

Option 2:
Make it static because any way IFC NAND driver polls to 
FSL_IFC_BANK_COUNT to know NAND flash chip select. This patch is doing same.

I don't understand what you're saying here.  The driver does not know at
compile time how many there are.  What this patch does is assume it's OK
to access non-existent registers in the rare case that there's no match
in the registers that exist.

Aaron tested this on P1010 and it seemed to work, though I'm not
generally fond of relying on such things.

-Scott