Re: [PATCH] fpga fr br: fix warning for unexpected version number

[matthew . gerlach]

On Wed, 5 Apr 2017, Moritz Fischer wrote:

Hi Matthew,


Hi Moritz,


On Wed, Apr 5, 2017 at 12:05 PM,  <matthew.gerl...@linux.intel.com> wrote:
From: Matthew Gerlach <matthew.gerl...@linux.intel.com>

The value in the version register of the altera freeze bridge
controller changed from the beta value of 2 to the
value of 0xad000003 in the official release of the IP.
This patch supports the old and new version numbers
without printing an warning.

Signed-off-by: Matthew Gerlach <matthew.gerl...@linux.intel.com>
---
 drivers/fpga/altera-freeze-bridge.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/fpga/altera-freeze-bridge.c 
b/drivers/fpga/altera-freeze-bridge.c
index 8dcd9fb..bdfd5eb 100644
--- a/drivers/fpga/altera-freeze-bridge.c
+++ b/drivers/fpga/altera-freeze-bridge.c
@@ -28,6 +28,7 @@
 #define FREEZE_CSR_REG_VERSION                 12

 #define FREEZE_CSR_SUPPORTED_VERSION           2
+#define FREEZE_CSR_OFFICIAL_VERSION            0xad000003

 #define FREEZE_CSR_STATUS_FREEZE_REQ_DONE      BIT(0)
 #define FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE    BIT(1)
@@ -241,10 +242,12 @@ static int altera_freeze_br_probe(struct platform_device 
*pdev)
                priv->enable = 1;

        revision = readl(priv->base_addr + FREEZE_CSR_REG_VERSION);
-       if (revision != FREEZE_CSR_SUPPORTED_VERSION)
+       if ((revision != FREEZE_CSR_SUPPORTED_VERSION) &&
+           (revision != FREEZE_CSR_OFFICIAL_VERSION))
                dev_warn(dev,
-                        "%s Freeze Controller unexpected revision %d != %d\n",
-                        __func__, revision, FREEZE_CSR_SUPPORTED_VERSION);
+                        "%s unexpected revision 0x%x != 0x%x != 0x%x\n",
+                        __func__, revision, FREEZE_CSR_SUPPORTED_VERSION,
+                        FREEZE_CSR_OFFICIAL_VERSION);

Maybe you actually wanna bail out if you read a random other value
instead of what you
expect instead of printing a warning.

I thought about making it an error if the version didn't match, but it was 
a dev_warn() before and that allowed folks to use the "old" driver with 
the new IP version.


        return fpga_bridge_register(dev, FREEZE_BRIDGE_NAME,
                                    &altera_freeze_br_br_ops, priv);
--
2.7.4


Cheers,

Moritz