On Mon, 31 Oct 2016, Ondrej Zary wrote:
> Write and read back MODE_REG to check if the chip is really there
> before doing more initialization.
>
> This prevents hang when incorrect I/O address was specified by user (in
> the most common case where no device is present there so all reads
> result in 0xff).
>
> Signed-off-by: Ondrej Zary <linux@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/scsi/g_NCR5380.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
> index 0d1f6ad..e713dba 100644
> --- a/drivers/scsi/g_NCR5380.c
> +++ b/drivers/scsi/g_NCR5380.c
> @@ -322,6 +322,13 @@ static int generic_NCR5380_init_one(struct scsi_host_template *tpnt,
> }
> }
>
> + /* check if the chip is really there */
> + NCR5380_write(MODE_REG, 0);
> + if (NCR5380_read(MODE_REG) != 0) {
Wouldn't it be more accurate to write,
/* Check for some kind of device. A vacant slot reads 0xff. */
?
> + ret = -ENODEV;
> + goto out_unregister;
> + }
> +
> ret = NCR5380_init(instance, flags | FLAG_LATE_DMA_SETUP);
> if (ret)
> goto out_unregister;
>
--
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