Re: [PATCH #upstream] sata_sil24: always set protocol override for non-ATAPI data commands

[Jeff Garzik <jeff@garzik.org>]

Robert Hancock wrote:
> The sil24 hardware has a built-in list of commands and associated protocols
> that gets used by default to decide how to handle a given command. However,
> if the command is not known to the controller then it presumably assumes it to
> be a non-data command which then causes protocol mismatch errors if the device
> ends up requesting data transfer. The new DATA SET MANAGEMENT - Trim command
> causes this issue since it's a DMA data-out command.
> 
> Since we should always know best what protocol the command should be using,
> let's just set the override flag to inform the controller what protocol to use
> for all non-ATAPI commands with data transfer.
> 
> Signed-off-by: Robert Hancock <hancockrwd@gmail.com>
> Tested-by: Mark Lord <liml@rtr.ca>
> 
> diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
> index 77aa8d7..e6946fc 100644
> --- a/drivers/ata/sata_sil24.c
> +++ b/drivers/ata/sata_sil24.c
> @@ -846,6 +846,17 @@ static void sil24_qc_prep(struct ata_queued_cmd *qc)
>  	if (!ata_is_atapi(qc->tf.protocol)) {
>  		prb = &cb->ata.prb;
>  		sge = cb->ata.sge;
> +		if (ata_is_data(qc->tf.protocol)) {
> +			u16 prot = 0;
> +			ctrl = PRB_CTRL_PROTOCOL;
> +			if (ata_is_ncq(qc->tf.protocol))
> +				prot |= PRB_PROT_NCQ;
> +			if (qc->tf.flags & ATA_TFLAG_WRITE)
> +				prot |= PRB_PROT_WRITE;
> +			else
> +				prot |= PRB_PROT_READ;
> +			prb->prot = cpu_to_le16(prot);
> +		}

I'm trying to remember why we did not do this originally -- Tejun, do 
you recall?

I do not see any prohibition in the docs, so I am inclined to apply this.

	Jeff