Re: [patch 1/7] libata: check for AN support

[Matt Sealey <matt@genesi-usa.com>]

Kristen Carlson Accardi wrote:
> Check to see if an ATAPI device supports Asynchronous Notification.
> If so, enable it.
> 
> Changes from last version:
> * use parens around id in ata.h
> 
> Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
> 
> Index: 2.6-git/drivers/ata/libata-core.c
> ===================================================================
> --- 2.6-git.orig/drivers/ata/libata-core.c
> +++ 2.6-git/drivers/ata/libata-core.c
> @@ -70,6 +70,7 @@ const unsigned long sata_deb_timing_long
>  static unsigned int ata_dev_init_params(struct ata_device *dev,
>  					u16 heads, u16 sectors);
>  static unsigned int ata_dev_set_xfermode(struct ata_device *dev);
> +static unsigned int ata_dev_set_AN(struct ata_device *dev);
>  static void ata_dev_xfermask(struct ata_device *dev);
>  
>  static unsigned int ata_print_id = 1;
> @@ -1744,6 +1745,22 @@ int ata_dev_configure(struct ata_device 
>  		}
>  		dev->cdb_len = (unsigned int) rc;
>  
> +		/*
> +		 * check to see if this ATAPI device supports
> +		 * Asynchronous Notification
> +		 */
> +		if ((ap->flags & ATA_FLAG_AN) && ata_id_has_AN(id)) {
> +			int err;
> +			/* issue SET feature command to turn this on */
> +			err = ata_dev_set_AN(dev);
> +			if (err)
> +				ata_dev_printk(dev, KERN_ERR,
> +						"unable to set AN, err %x\n",
> +						err);
> +			else
> +				dev->flags |= ATA_DFLAG_AN;
> +		}
> +
>  		if (ata_id_cdb_intr(dev->id)) {
>  			dev->flags |= ATA_DFLAG_CDB_INTR;
>  			cdb_intr_string = ", CDB intr";
> @@ -3525,6 +3542,42 @@ static unsigned int ata_dev_set_xfermode
>  }
>  
>  /**
> + *	ata_dev_set_AN - Issue SET FEATURES - SATA FEATURES
> + *                       with sector count set to indicate
> + *                       Asynchronous Notification feature
> + *	@dev: Device to which command will be sent
> + *
> + *	Issue SET FEATURES - SATA FEATURES command to device @dev
> + *	on port @ap.
> + *
> + *	LOCKING:
> + *	PCI/etc. bus probe sem.
> + *
> + *	RETURNS:
> + *	0 on success, AC_ERR_* mask otherwise.
> + */
> +static unsigned int ata_dev_set_AN(struct ata_device *dev)
> +{
> +	struct ata_taskfile tf;
> +	unsigned int err_mask;
> +
> +	/* set up set-features taskfile */
> +	DPRINTK("set features - SATA features\n");
> +
> +	ata_tf_init(dev, &tf);
> +	tf.command = ATA_CMD_SET_FEATURES;
> +	tf.feature = SETFEATURES_SATA_ENABLE;
> +	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
> +	tf.protocol = ATA_PROT_NODATA;
> +	tf.nsect = SATA_AN;
> +
> +	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0);
> +
> +	DPRINTK("EXIT, err_mask=%x\n", err_mask);
> +	return err_mask;
> +}
> +
> +/**
>   *	ata_dev_init_params - Issue INIT DEV PARAMS command
>   *	@dev: Device to which command will be sent
>   *	@heads: Number of heads (taskfile parameter)
> Index: 2.6-git/include/linux/ata.h
> ===================================================================
> --- 2.6-git.orig/include/linux/ata.h
> +++ 2.6-git/include/linux/ata.h
> @@ -194,6 +194,12 @@ enum {
>  	SETFEATURES_WC_ON	= 0x02, /* Enable write cache */
>  	SETFEATURES_WC_OFF	= 0x82, /* Disable write cache */
>  
> +	SETFEATURES_SATA_ENABLE = 0x10, /* Enable use of SATA feature */
> +	SETFEATURES_SATA_DISABLE = 0x90, /* Disable use of SATA feature */
> +
> +	/* SETFEATURE Sector counts for SATA features */
> +	SATA_AN			= 0x05,  /* Asynchronous Notification */
> +
>  	/* ATAPI stuff */
>  	ATAPI_PKT_DMA		= (1 << 0),
>  	ATAPI_DMADIR		= (1 << 2),	/* ATAPI data dir:
> @@ -299,6 +305,9 @@ struct ata_taskfile {
>  #define ata_id_queue_depth(id)	(((id)[75] & 0x1f) + 1)
>  #define ata_id_removeable(id)	((id)[0] & (1 << 7))
>  #define ata_id_has_dword_io(id)	((id)[50] & (1 << 0))
> +#define ata_id_has_AN(id)	\
> +	( (((id)[76] != 0x0000) && ((id)[76] != 0xffff)) && \
> +	  ((id)[78] & (1 << 5)) )

??

> --- 2.6-git.orig/include/linux/libata.h
> +++ 2.6-git/include/linux/libata.h
> @@ -136,6 +136,7 @@ enum {
>  	ATA_DFLAG_CDB_INTR	= (1 << 2), /* device asserts INTRQ when ready for CDB */
>  	ATA_DFLAG_NCQ		= (1 << 3), /* device supports NCQ */
>  	ATA_DFLAG_FLUSH_EXT	= (1 << 4), /* do FLUSH_EXT instead of FLUSH */
> +	ATA_DFLAG_AN		= (1 << 5), /* device supports Async notification */
>  	ATA_DFLAG_CFG_MASK	= (1 << 8) - 1,

Why don't the macros use the enums? It makes the code hard to read without
painful cross-reference doesn't it? Surely (id)[76] & (ATA_DFLAG_AN) is a
lot more readable than 1 << 5 - even if the flag is obviously that, a lot
of values and registers can have 1 << 5 as a flag and mean a lot of different
things.

-- 
Matt Sealey <matt@genesi-usa.com>
Genesi, Manager, Developer Relations