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

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Date:   Wed, 5 Apr 2017 13:12:15 -0700
From:   Moritz Fischer <mdf@...nel.org>
To:     matthew.gerlach@...ux.intel.com
Cc:     Alan Tull <atull@...nel.org>, linux-fpga@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fpga fr br: fix warning for unexpected version number

Hi Matthew,

On Wed, Apr 5, 2017 at 12:05 PM,  <matthew.gerlach@...ux.intel.com> wrote:
> From: Matthew Gerlach <matthew.gerlach@...ux.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.gerlach@...ux.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.
>
>         return fpga_bridge_register(dev, FREEZE_BRIDGE_NAME,
>                                     &altera_freeze_br_br_ops, priv);
> --
> 2.7.4
>

Cheers,

Moritz