Re: [PATCH] Xilinx: hwicap: cleanup polling timeout.

["Grant Likely" <grant.likely@secretlab.ca>]

On Mon, May 5, 2008 at 12:20 PM, Stephen Neuendorffer
<stephen.neuendorffer@xilinx.com> wrote:
> In order to avoid polling forever if an error occurs, this driver
>  includes a timeout counter.  However, in fast systems, this counter
>  wasn't high enough.  This patch fixes the bug and also makes the
>  buffer-based and fifo-based drivers return the same error condition on
>  a timeout (-EIO).

Would it be better to base the timeout on real time instead of a hard
iteration count?

Cheers,
g.

>
>  Signed-off-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
>  ---
>   drivers/char/xilinx_hwicap/buffer_icap.c   |   10 ++++++++--
>   drivers/char/xilinx_hwicap/fifo_icap.c     |    9 +++++++++
>   drivers/char/xilinx_hwicap/xilinx_hwicap.h |    3 ---
>   3 files changed, 17 insertions(+), 5 deletions(-)
>
>  diff --git a/drivers/char/xilinx_hwicap/buffer_icap.c b/drivers/char/xilinx_hwicap/buffer_icap.c
>  index aa7f796..0993883 100644
>  --- a/drivers/char/xilinx_hwicap/buffer_icap.c
>  +++ b/drivers/char/xilinx_hwicap/buffer_icap.c
>  @@ -35,6 +35,12 @@
>
>   #include "buffer_icap.h"
>
>  +/* Number of times to poll the done register.  This has to be large
>  +   enough to allow an entire configuration to complete. If an entire
>  +   page (4kb) is configured at once, that could take up to 4k cycles
>  +   with a byte-wide icap interface. */
>  +#define XHI_MAX_RETRIES     5000
>  +
>   /* Indicates how many bytes will fit in a buffer. (1 BRAM) */
>   #define XHI_MAX_BUFFER_BYTES        2048
>   #define XHI_MAX_BUFFER_INTS         (XHI_MAX_BUFFER_BYTES >> 2)
>  @@ -208,7 +214,7 @@ static int buffer_icap_device_read(struct hwicap_drvdata *drvdata,
>         while (buffer_icap_busy(base_address)) {
>                 retries++;
>                 if (retries > XHI_MAX_RETRIES)
>  -                       return -EBUSY;
>  +                       return -EIO;
>         }
>         return 0;
>
>  @@ -242,7 +248,7 @@ static int buffer_icap_device_write(struct hwicap_drvdata *drvdata,
>         while (buffer_icap_busy(base_address)) {
>                 retries++;
>                 if (retries > XHI_MAX_RETRIES)
>  -                       return -EBUSY;
>  +                       return -EIO;
>         }
>         return 0;
>
>  diff --git a/drivers/char/xilinx_hwicap/fifo_icap.c b/drivers/char/xilinx_hwicap/fifo_icap.c
>  index 776b505..d1cd928 100644
>  --- a/drivers/char/xilinx_hwicap/fifo_icap.c
>  +++ b/drivers/char/xilinx_hwicap/fifo_icap.c
>  @@ -35,6 +35,15 @@
>
>   #include "fifo_icap.h"
>
>  +/* Number of times to poll the done register.  This has to be large
>  + * enough to allow an entire configuration to complete.  If an entire
>  + * page (4kb) is configured at once, that could take up to 4k cycles
>  + * with a byte-wide icap interface.  In most cases, this driver is
>  + * used with a much smaller fifo, but this should be sufficient in the
>  + * worst case.
>  + */
>  +#define XHI_MAX_RETRIES     5000
>  +
>   /* Register offsets for the XHwIcap device. */
>   #define XHI_GIER_OFFSET        0x1C  /* Device Global Interrupt Enable Reg */
>   #define XHI_IPISR_OFFSET 0x20  /* Interrupt Status Register */
>  diff --git a/drivers/char/xilinx_hwicap/xilinx_hwicap.h b/drivers/char/xilinx_hwicap/xilinx_hwicap.h
>  index 1f9c8b0..fd4be31 100644
>  --- a/drivers/char/xilinx_hwicap/xilinx_hwicap.h
>  +++ b/drivers/char/xilinx_hwicap/xilinx_hwicap.h
>  @@ -89,9 +89,6 @@ struct hwicap_driver_config {
>         void (*reset)(struct hwicap_drvdata *drvdata);
>   };
>
>  -/* Number of times to poll the done regsiter */
>  -#define XHI_MAX_RETRIES     10
>  -
>   /************ Constant Definitions *************/
>
>   #define XHI_PAD_FRAMES              0x1
>  --
>  1.5.3.4-dirty
>
>
>
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.