Re: [RFC] add DMA setup FIS auto-activate feature

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Shaohua Li wrote:

> hi,
> The SATA spec defines DMA setup FIS auto-activate optimization for FPDMA
> transfers. I had an attempt to add it, though my test doesn't show obvious
> performance improvement (not worse too), I wonder why not add this feature?
>
> Signed-off-by: Shaohua Li <shaohua.li@intel.com>
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 2c6aeda..53cc355 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -2303,6 +2303,7 @@ static void ata_dev_config_ncq(struct ata_device *dev,
>  {
>  	struct ata_port *ap = dev->link->ap;
>  	int hdepth = 0, ddepth = ata_id_queue_depth(dev->id);
> +	const u16 *id = dev->id;
>   

   Why introduce the variable if you're only using it once?

>  	if (!ata_id_has_ncq(dev->id)) {
>   

   Should be changed to just 'id'...

>  		desc[0] = '\0';
> @@ -2317,6 +2318,9 @@ static void ata_dev_config_ncq(struct ata_device *dev,
>  		dev->flags |= ATA_DFLAG_NCQ;
>  	}
>  
> +	if (ata_id_has_daa(id))
> +		ata_dev_set_feature(dev, SETFEATURES_SATA_ENABLE, SATA_DAA);
> +
>   

MBR, Sergei