Re: [PATCH] libata: fallback to the other IDENTIFY on device error

[Jeff Garzik <jeff@garzik.org>]

Tejun Heo wrote:
> It seems the world isn't as frank as we thought and some devices lie
> about who they are.  Fallback to the other IDENTIFY if IDENTIFY fails
> with device error.  As this is the strategy used by IDE for a long
> time, it shouldn't cause too much problem.
> 
> Signed-off-by: Tejun Heo <htejun@gmail.com>
> Cc: William Thompson <wt@electro-mechanical.com>
> ---
> Willam, please verify this fixes your problem.  Jeff, after all, we
> seem to need this.  :-(
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index ca67484..f543109 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -1652,7 +1652,7 @@ int ata_dev_read_id(struct ata_device *d
>  	struct ata_taskfile tf;
>  	unsigned int err_mask = 0;
>  	const char *reason;
> -	int tried_spinup = 0;
> +	int may_fallback = 1, tried_spinup = 0;
>  	int rc;
>  
>  	if (ata_msg_ctl(ap))
> @@ -1696,11 +1696,30 @@ int ata_dev_read_id(struct ata_device *d
>  			return -ENOENT;
>  		}
>  
> +		if (may_fallback && (err_mask == AC_ERR_DEV)) {
> +			may_fallback = 0;
> +
> +			/* Device or controller might have reported
> +			 * the wrong device class.  Give a shot at then
> +			 * other IDENTIFY
> +			 */
> +			if (class == ATA_DEV_ATA)
> +				class = ATA_DEV_ATAPI;
> +			else
> +				class = ATA_DEV_ATA;

The error handling should be more specific -- check and make sure the 
error is 'command aborted'

	Jeff