Message-Id: <20090126205717.0c528c88.akpm@linux-foundation.org>
Date:	Mon, 26 Jan 2009 20:57:17 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Peer Chen <pchen@...dia.com>, jeff@...zik.org,
	Kuan Luo <kluo@...dia.com>,
	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] sata_nv: sgpio for nvidia mcp55 -v3

On Wed, 21 Jan 2009 18:32:15 -0800 Yinghai Lu <yinghai@...nel.org> wrote:

> 
> Impact: new features
> 
> based on patch on
>     http://marc.info/?l=linux-ide&m=116289338705418&w=2
> 
> 1. update the patch for 2.6.19 to latest upstream ( 2.6.28?)
> 2. fix shared sgpio to support several mcp55 + io55, so every mcp55 have
>    seperate spinlock
> 3. use scratch_source as numbering of sgpio instead of address of struct,
>    so could go through kexec/kdump
> 
> v2: revert NV_ON and NV_OFF, so turn on Activity LED all the time when disk is idle.
> v3: use one timer per sgpio instead of per nv_host, so for mcp55+io55 system will use 2 timers
>     instead of 6 timers.

None of this is really usable as a changelog.  The original text from
the 2006 patch was better.

> Signed-off-by: Yinghai Lu <yinghai@...nel.org>

Signoffs from Kuan Luo and Peer Chen would be appropriate here.

Please include a full changelog with the next version incorporating the
above comments.  Information about how this version of the patch has
changed from the previous version _is_ useful for reviewers, but is not
appropriate for the permanent changelog.  Hence many people put this
material below the ^--- line in the changelog.

> --- linux-2.6.orig/drivers/ata/sata_nv.c
> +++ linux-2.6/drivers/ata/sata_nv.c
> @@ -200,6 +200,164 @@ enum {
>  
>  };
>  
> +/* sgpio
> + * Sgpio defines
> + * SGPIO state defines
> + */
> +#define NV_SGPIO_STATE_RESET		0
> +#define NV_SGPIO_STATE_OPERATIONAL	1
> +#define NV_SGPIO_STATE_ERROR		2
> +
> +/* SGPIO command opcodes */
> +#define NV_SGPIO_CMD_RESET		0
> +#define NV_SGPIO_CMD_READ_PARAMS	1
> +#define NV_SGPIO_CMD_READ_DATA		2
> +#define NV_SGPIO_CMD_WRITE_DATA		3
> +
> +/* SGPIO command status defines */
> +#define NV_SGPIO_CMD_OK			0
> +#define NV_SGPIO_CMD_ACTIVE		1
> +#define NV_SGPIO_CMD_ERR		2
> +
> +#define NV_SGPIO_UPDATE_TICK		90
> +#define NV_CNTRLR_SHARE_INIT		2
> +#define NV_SGPIO_MAX_ACTIVITY_ON	10
> +#define NV_SGPIO_MIN_FORCE_OFF		5
> +#define NV_SGPIO_PCI_CSR_OFFSET		0x58
> +#define NV_SGPIO_PCI_CB_OFFSET		0x5C
> +#define NV_SGPIO_DFLT_CB_SIZE		256
> +#define NV_ON				0
> +#define NV_OFF				1
> +
> +static inline u8 bf_extract(u8 value, u8 offset, u8 bit_count)
> +{
> +	return (((u8)(value)) >> (offset)) & ((1 << (bit_count)) - 1);
> +}
> +
> +static inline u8 bf_ins(u8 value, u8 ins, u8 offset, u8 bit_count)
> +{
> +	return	((value) & ~((((1 << (bit_count)) - 1)) << (offset))) |
> +						(((u8)(ins)) << (offset));
> +}
> +
> +static inline u32 bf_extract_u32(u32 value, u8 offset, u8 bit_count)
> +{
> +	return (((u32)(value)) >> (offset)) & ((1 << (bit_count)) - 1);
> +}
> +static inline u32 bf_ins_u32(u32 value, u32 ins, u8 offset, u8 bit_count)
> +{
> +	return	((value) & ~((((1 << (bit_count)) - 1)) << (offset))) |
> +						(((u32)(ins)) << (offset));
> +}

These helpers are generic and I would suggest that it would be better
to propose generic kernel-wide implementations and merge that
separately.

A suitable starting point might be drivers/net/3c59x.c's BFEXT() and
BFINS() macros.  With a bit of thought and testing, those macros could
be made to work with any size of input args, so we would then not need
separate u8, u16, u32 and u64 implementations.

> +#define GET_SGPIO_STATUS(v)	bf_extract(v, 0, 2)
> +#define GET_CMD_STATUS(v)	bf_extract(v, 3, 2)
> +#define GET_CMD(v)		bf_extract(v, 5, 3)
> +#define SET_CMD(v, cmd)	bf_ins(v, cmd, 5, 3)
> +
> +#define GET_ENABLE(v)		bf_extract(v, 23, 1)
> +#define SET_ENABLE(v)		bf_ins_u32(v, 1, 23, 1)
> +
> +/* Needs to have a u8 bit-field insert. */
> +#define GET_ACTIVITY(v)		bf_extract(v, 5, 3)
> +#define SET_ACTIVITY(v, on_off)	bf_ins(v, on_off, 5, 3)
> +
> +union nv_sgpio_nvcr {
> +	struct {
> +		u8	init_cnt;
> +		u8	cb_size;
> +		u8	cbver;
> +		u8	rsvd;
> +	} bit;
> +	u32	all;
> +};

What are the endianness considerations here?

> +union nv_sgpio_tx {
> +	u8	tx_port[4];
> +	u32	all;
> +};
> +
> +struct nv_sgpio_cb {
> +	u64			scratch_space;
> +	union nv_sgpio_nvcr	nvcr;
> +	u32			cr0;
> +	u32                     rsvd[4];
> +	union nv_sgpio_tx       tx[2];
> +};
> +
> +#define NR_SGPIO_SHARE_HOST 4
> +struct nv_sgpio_host_share {
> +	spinlock_t		lock;
> +	struct timer_list	timer;
> +	unsigned int		need_update;
> +	struct ata_host		*host[NR_SGPIO_SHARE_HOST];
> +};
> +
> +struct nv_sgpio_host_flags {
> +	u8	sgpio_enabled:1;
> +	u8	need_update:1;
> +	u8	rsvd:6;
> +};

The individual fields share a byte.  Is locking needed to prevent races
when updating them?  If not, why not?  If so, what is that locking
protocol?  A comment should be added here describing this.

> +struct nv_host_sgpio {
> +	struct nv_sgpio_host_flags	flags;
> +	u8				*pcsr;
> +	struct nv_sgpio_cb		*pcb;
> +	unsigned  int			share_index;
> +};
> +
> +struct nv_sgpio_port_flags {
> +	u8	last_state:1;
> +	u8	recent_activity:1;
> +	u8	rsvd:6;
> +};
> +
> +struct nv_sgpio_led {
> +	struct nv_sgpio_port_flags	flags;
> +	u8				force_off;
> +	u8				last_cons_active;
> +};
> +
> +struct nv_port_sgpio {
> +	struct nv_sgpio_led	activity;
> +};
> +
> +/* 1 mcp55 and 3 io55, 0 is not used */
> +#define NR_SGPIO 5
> +static struct nv_sgpio_host_share nv_sgpio_share[NR_SGPIO];
> +
> +static inline u8 nv_sgpio_get_func(struct ata_host *host)
> +{
> +	u8 devfn = (to_pci_dev(host->dev))->devfn;
> +
> +	return PCI_FUNC(devfn);
> +}
> +
> +static inline u8 nv_sgpio_tx_host_offset(struct ata_host *host)
> +{
> +	return nv_sgpio_get_func(host)/NV_CNTRLR_SHARE_INIT;
> +}
> +
> +static inline u8 nv_sgpio_calc_tx_offset(u8 cntrlr, u8 channel)
> +{
> +	return sizeof(union nv_sgpio_tx) - (NV_CNTRLR_SHARE_INIT *
> +		(cntrlr % NV_CNTRLR_SHARE_INIT)) - channel - 1;
> +}
> +
> +static inline u8 nv_sgpio_tx_port_offset(struct ata_port *ap)
> +{
> +	u8 cntrlr = nv_sgpio_get_func(ap->host);
> +	return nv_sgpio_calc_tx_offset(cntrlr, ap->port_no);
> +}
> +
> +static inline u8 nv_sgpio_capable(const struct pci_device_id *ent)
> +{
> +	if (ent->device == PCI_DEVICE_ID_NVIDIA_NFORCE_MCP55_SATA2)
> +		return 1;
> +	else
> +		return 0;
> +}
> +
>  /* ADMA Physical Region Descriptor - one SG segment */
>  struct nv_adma_prd {
>  	__le64			addr;
> @@ -240,6 +398,7 @@ struct nv_adma_cpb {
>  
>  
>  struct nv_adma_port_priv {
> +	struct nv_port_sgpio	port_sgpio;
>  	struct nv_adma_cpb	*cpb;
>  	dma_addr_t		cpb_dma;
>  	struct nv_adma_prd	*aprd;
> @@ -254,6 +413,12 @@ struct nv_adma_port_priv {
>  
>  struct nv_host_priv {
>  	unsigned long		type;
> +	unsigned long		host_flags;
> +	struct nv_host_sgpio	host_sgpio;
> +};
> +
> +struct nv_port_priv {
> +	struct nv_port_sgpio	port_sgpio;
>  };
>  
>  struct defer_queue {
> @@ -271,6 +436,8 @@ enum ncq_saw_flag_list {
>  };
>  
>  struct nv_swncq_port_priv {
> +	struct nv_port_sgpio	port_sgpio;
> +
>  	struct ata_prd	*prd;	 /* our SG list */
>  	dma_addr_t	prd_dma; /* and its DMA mapping */
>  	void __iomem	*sactive_block;
> @@ -311,6 +478,10 @@ static int nv_nf2_hardreset(struct ata_l
>  			    unsigned long deadline);
>  static void nv_ck804_freeze(struct ata_port *ap);
>  static void nv_ck804_thaw(struct ata_port *ap);
> +static int nv_port_start(struct ata_port *ap);
> +static void nv_port_stop(struct ata_port *ap);
> +static void nv_host_stop(struct ata_host *host);
> +static unsigned int nv_qc_issue(struct ata_queued_cmd *qc);
>  static int nv_adma_slave_config(struct scsi_device *sdev);
>  static int nv_adma_check_atapi_dma(struct ata_queued_cmd *qc);
>  static void nv_adma_qc_prep(struct ata_queued_cmd *qc);
> @@ -374,6 +545,17 @@ static const struct pci_device_id nv_pci
>  	{ } /* terminate list */
>  };
>  
> +/* SGPIO function prototypes */
> +static void nv_sgpio_init(struct pci_dev *pdev, struct ata_host *host);
> +static void nv_sgpio_reset(u8 *pcsr);
> +static void nv_sgpio_set_timer(struct timer_list *ptimer,
> +				unsigned int timeout_msec);
> +static void nv_sgpio_timer_handler(unsigned long ptr);
> +static void nv_sgpio_host_cleanup(struct nv_host_priv *host);
> +static u8 nv_sgpio_update_led(struct nv_sgpio_led *led, u8 *on_off);
> +static void nv_sgpio_clear_all_leds(struct ata_port *ap);
> +static u8 nv_sgpio_send_cmd(struct nv_sgpio_host_share *sgpio_share, u8 cmd);
> +
>  static struct pci_driver nv_pci_driver = {
>  	.name			= DRV_NAME,
>  	.id_table		= nv_pci_tbl,
> @@ -409,6 +591,10 @@ static struct ata_port_operations nv_com
>  	.inherits		= &ata_bmdma_port_ops,
>  	.scr_read		= nv_scr_read,
>  	.scr_write		= nv_scr_write,
> +	.qc_issue               = nv_qc_issue,
> +	.port_start		= nv_port_start,
> +	.port_stop		= nv_port_stop,
> +	.host_stop		= nv_host_stop,
>  };
>  
>  /* OSDL bz11195 reports that link doesn't come online after hardreset
> @@ -1395,6 +1581,8 @@ static unsigned int nv_adma_qc_issue(str
>  	void __iomem *mmio = pp->ctl_block;
>  	int curr_ncq = (qc->tf.protocol == ATA_PROT_NCQ);
>  
> +	pp->port_sgpio.activity.flags.recent_activity = NV_ON;
> +
>  	VPRINTK("ENTER\n");
>  
>  	/* We can't handle result taskfile with NCQ commands, since
> @@ -1673,6 +1861,34 @@ static void nv_adma_error_handler(struct
>  	ata_sff_error_handler(ap);
>  }
>  
> +static int nv_port_start(struct ata_port *ap)
> +{
> +	struct device *dev = ap->host->dev;
> +	struct nv_port_priv *pp;
> +	int rc;
> +
> +	rc = ata_sff_port_start(ap);
> +	if (rc)
> +		return rc;
> +
> +	pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL);
> +	if (!pp)
> +		return -ENOMEM;

Did we just leak the resources allocated by ata_sff_port_start()?

> +	ap->private_data = pp;
> +
> +	return 0;
> +}
> +
> +static unsigned int nv_qc_issue(struct ata_queued_cmd *qc)
> +{
> +       struct nv_port_priv *port = qc->ap->private_data;
> +
> +       port->port_sgpio.activity.flags.recent_activity = NV_ON;
> +
> +       return ata_sff_qc_issue(qc);
> +}
> +
>  static void nv_swncq_qc_to_dq(struct ata_port *ap, struct ata_queued_cmd *qc)
>  {
>  	struct nv_swncq_port_priv *pp = ap->private_data;
> @@ -2017,6 +2233,8 @@ static unsigned int nv_swncq_qc_issue(st
>  	struct ata_port *ap = qc->ap;
>  	struct nv_swncq_port_priv *pp = ap->private_data;
>  
> +	pp->port_sgpio.activity.flags.recent_activity = NV_ON;
> +
>  	if (qc->tf.protocol != ATA_PROT_NCQ)
>  		return ata_sff_qc_issue(qc);
>  
> @@ -2404,6 +2622,9 @@ static int nv_init_one(struct pci_dev *p
>  	} else if (type == SWNCQ)
>  		nv_swncq_host_init(host);
>  
> +	if (nv_sgpio_capable(ent))
> +		nv_sgpio_init(pdev, host);
> +
>  	pci_set_master(pdev);
>  	return ata_host_activate(host, pdev->irq, ipriv->irq_handler,
>  				 IRQF_SHARED, ipriv->sht);
> @@ -2459,11 +2680,19 @@ static int nv_pci_device_resume(struct p
>  }
>  #endif
>  
> +static void nv_port_stop(struct ata_port *ap)
> +{
> +	nv_sgpio_clear_all_leds(ap);
> +}

I'd have expected a function called nv_port_stop() to release all the
resources which were allocated by a function called nv_port_start().

I guess the dmam_*() crap^Whelpers do that.

>  static void nv_ck804_host_stop(struct ata_host *host)
>  {
>  	struct pci_dev *pdev = to_pci_dev(host->dev);
> +	struct nv_host_priv *phost = host->private_data;
>  	u8 regval;
>  
> +	nv_sgpio_host_cleanup(phost);
> +
>  	/* disable SATA space for CK804 */
>  	pci_read_config_byte(pdev, NV_MCP_SATA_CFG_20, &regval);
>  	regval &= ~NV_MCP_SATA_CFG_20_SATA_SPACE_EN;
> @@ -2487,6 +2716,339 @@ static void nv_adma_host_stop(struct ata
>  	nv_ck804_host_stop(host);
>  }
>  
> +static void nv_host_stop(struct ata_host *host)
> +{
> +	struct nv_host_priv *phost = host->private_data;
> +
> +	nv_sgpio_host_cleanup(phost);
> +}
> +
> +static void nv_sgpio_init(struct pci_dev *pdev, struct ata_host *host)
> +{
> +	u16 csr_add;
> +	u32 cb_add, temp32;
> +	struct nv_host_priv *phost = host->private_data;
> +	struct nv_host_sgpio *host_sgpio;
> +	struct nv_sgpio_host_share *sgpio_share;
> +	struct nv_sgpio_cb *pcb;
> +	u8 pro = 0;
> +	unsigned int share_index;
> +	int i;
> +
> +	pci_read_config_word(pdev, NV_SGPIO_PCI_CSR_OFFSET, &csr_add);
> +	pci_read_config_dword(pdev, NV_SGPIO_PCI_CB_OFFSET, &cb_add);
> +

> +		return;
> +
> +	if (cb_add <= 0x80000 || cb_add >= 0x9FC00)
> +		return;

The magic numbers at least need an explanatory comment?

> +	pci_read_config_byte(pdev, 0xA4, &pro);
> +	if (!(pro & 0x40))
> +		return;
> +
> +	temp32 = csr_add;
> +	if (temp32 <= 0x200 || temp32 >= 0xFFFE)

??

> +		return;
> +
> +	dev_printk(KERN_DEBUG, &pdev->dev, "CSR 0x%x CB 0x%x\n",
> +			 csr_add, cb_add);
> +
> +	host_sgpio = &phost->host_sgpio;
> +	pcb = ioremap(cb_add, 256);
> +
> +	if (pcb->nvcr.bit.init_cnt != 0x2 || pcb->nvcr.bit.cbver != 0x0)
> +		return;
> +
> +	share_index = pcb->scratch_space;
> +	if (share_index == 0 || share_index > (NR_SGPIO - 1)) {
> +		/* find one good position */
> +		for (i = 1; i < NR_SGPIO; i++) {
> +			if (!nv_sgpio_share[i].host[0]) {
> +				share_index = i;
> +				break;
> +			}
> +		}
> +		if (share_index == 0 || share_index > (NR_SGPIO - 1)) {
> +			printk(KERN_WARNING "NR_SGPIO %d is too small\n",
> +				 NR_SGPIO);

dev_warn()?

It's good to make the printks identify which driver (and sometimes
device) they are referring to.

> +			return;
> +		}
> +	}
> +
> +	host_sgpio->pcsr = (void *)(unsigned long)temp32;
> +	host_sgpio->pcb = pcb;
> +	sgpio_share = &nv_sgpio_share[share_index];
> +	if (!sgpio_share->host[0]) {
> +		/* also handle kexec path:
> +		 * scratch_space is set, but not get nv_sgpio_share yet
> +		 */

hm.  What has this to do with kexec?

> +		spin_lock_init(&sgpio_share->lock);
> +		spin_lock(&sgpio_share->lock);
> +		sgpio_share->host[0] = host;
> +		host_sgpio->share_index = share_index;
> +		pcb->scratch_space = share_index;
> +		nv_sgpio_reset(host_sgpio->pcsr);
> +		pcb->cr0 = SET_ENABLE(pcb->cr0);
> +		init_timer(&sgpio_share->timer);
> +		sgpio_share->timer.data = (unsigned long)sgpio_share;
> +		nv_sgpio_set_timer(&sgpio_share->timer, NV_SGPIO_UPDATE_TICK);
> +		spin_unlock(&sgpio_share->lock);
> +	} else {
> +		spin_lock(&sgpio_share->lock);
> +		for (i = 1; i < NR_SGPIO_SHARE_HOST; i++) {
> +			if (!sgpio_share->host[i]) {
> +				sgpio_share->host[i] = host;
> +				host_sgpio->share_index = share_index;
> +				break;
> +			}
> +		}
> +		if (i == NR_SGPIO_SHARE_HOST)
> +			printk(KERN_WARNING "NR_SGPIO_SHARE_HOST %d is too small\n",
> +					 NR_SGPIO_SHARE_HOST);
> +		spin_unlock(&sgpio_share->lock);
> +	}

The handling of sgpio_share->timer is confusing.

We can return from this function without having run init_timer() at
all.  Why is this not buggy?

Looking at the (obscure, undercommented) tricks which nv_sgpio_init()
is doing I can kinda sorta see how it works, but I think it should be
double-checked and simplified and clarified if poss.

> +	dev_printk(KERN_DEBUG, &pdev->dev, "using sgpio %d\n", share_index);
> +	host_sgpio->flags.sgpio_enabled = 1;
> +
> +}
> +
> +static void nv_sgpio_set_timer(struct timer_list *ptimer,
> +			       unsigned int timeout_msec)
> +{
> +	if (!ptimer)
> +		return;
> +	ptimer->function = nv_sgpio_timer_handler;
> +	ptimer->expires = msecs_to_jiffies(timeout_msec) + jiffies;
> +	add_timer(ptimer);
> +}

It would be better (I think) if this function were to also be passed
the timer.data argument, and if it were to also run init_timer().  Then
it could use the setup_timer() helper also.

> +static void nv_sgpio_timer_handler(unsigned long context)
> +{
> +
> +	struct nv_sgpio_host_share *sgpio_share = (struct nv_sgpio_host_share *)context;
> +	struct ata_host *host;
> +	struct nv_host_priv *phost;
> +	u8 count, host_offset, port_offset;
> +	union nv_sgpio_tx tx;
> +	u8 on_off;
> +	unsigned long mask;
> +	struct nv_port_priv *port;
> +	struct nv_host_sgpio *host_sgpio;
> +	struct nv_sgpio_cb *pcb;
> +	int i;
> +
> +	for (i = 0; i < NR_SGPIO_SHARE_HOST; i++) {
> +		host = sgpio_share->host[i];
> +		/* not blank slot */
> +		if (!host)
> +			break;
> +
> +		phost = (struct nv_host_priv *)host->private_data;

Unneeded, undesirable cast of void*.  Please check the whole patch for this.

> +		host_sgpio = &phost->host_sgpio;
> +		if (!host_sgpio->flags.sgpio_enabled)
> +			continue;
> +
> +		mask = 0xFFFF;
> +		host_offset = nv_sgpio_tx_host_offset(host);
> +		pcb = host_sgpio->pcb;
> +
> +		spin_lock(&sgpio_share->lock);
> +		tx = pcb->tx[host_offset];
> +		spin_unlock(&sgpio_share->lock);

This is interrupt-context code and it takes a spinlock.  But other,
non-interrupt-context code takes the same lock with a bare spin_lock(),
not with spin_lock_bh() or spin_lock_irq() or whatever.

Why is this not deadlocky?  Did it pass lockdep testing?

> +		for (count = 0; count < host->n_ports; count++) {
> +			struct ata_port *ap;
> +
> +			ap = host->ports[count];
> +
> +			if (!(ap && !(ap->flags & ATA_FLAG_DISABLED)))

That expression hurts my brain.  It is equivalent to

			if (!ap || (ap->flags & ATA_FLAG_DISABLED))

which I think is a heck of a lot clearer?

> +				continue;
> +
> +			port = (struct nv_port_priv *)ap->private_data;

unneeded cast?

> +			if (!port)
> +				continue;
> +			port_offset = nv_sgpio_tx_port_offset(ap);
> +			on_off = GET_ACTIVITY(tx.tx_port[port_offset]);
> +			if (nv_sgpio_update_led(&port->port_sgpio.activity, &on_off)) {
> +				tx.tx_port[port_offset] =
> +					SET_ACTIVITY(tx.tx_port[port_offset], on_off);
> +				host_sgpio->flags.need_update = 1;
> +		       }
> +		}
> +
> +		if (host_sgpio->flags.need_update) {
> +			sgpio_share->need_update = 1;
> +			spin_lock(&sgpio_share->lock);
> +			if (nv_sgpio_get_func(host)
> +				% NV_CNTRLR_SHARE_INIT == 0) {
> +				pcb->tx[host_offset].all &= mask;
> +				mask = mask << 16;
> +				tx.all &= mask;
> +			} else {
> +				tx.all &= mask;
> +				mask = mask << 16;
> +				pcb->tx[host_offset].all &= mask;
> +			}
> +			pcb->tx[host_offset].all |= tx.all;
> +			spin_unlock(&sgpio_share->lock);
> +		}
> +	}
> +
> +	if (sgpio_share->need_update) {
> +		if (nv_sgpio_send_cmd(sgpio_share, NV_SGPIO_CMD_WRITE_DATA)) {
> +			sgpio_share->need_update = 0;
> +			for (i = 0; i < NR_SGPIO_SHARE_HOST; i++) {
> +				host = sgpio_share->host[i];
> +				/* not blank slot */
> +				if (!host)
> +					break;
> +
> +				phost = (struct nv_host_priv *)host->private_data;

cast?

> +
> +				host_sgpio = &phost->host_sgpio;
> +				if (!host_sgpio->flags.sgpio_enabled)
> +					continue;
> +
> +				host_sgpio->flags.need_update = 0;
> +			}
> +		}
> +	}
> +
> +	nv_sgpio_set_timer(&sgpio_share->timer, NV_SGPIO_UPDATE_TICK);
> +	return;
> +}
> +
> +static u8 nv_sgpio_send_cmd(struct nv_sgpio_host_share *sgpio_share, u8 cmd)
> +{
> +	u8 csr;
> +	struct nv_host_sgpio *host_sgpio;
> +	struct nv_host_priv *phost;
> +
> +	phost = (struct nv_host_priv *)sgpio_share->host[0]->private_data;

etc..

> +	host_sgpio = &phost->host_sgpio;
> +	spin_lock(&sgpio_share->lock);
> +	csr = inb((unsigned long)host_sgpio->pcsr);
> +	if ((GET_SGPIO_STATUS(csr) != NV_SGPIO_STATE_OPERATIONAL) ||
> +	    (GET_CMD_STATUS(csr) == NV_SGPIO_CMD_ACTIVE)) {
> +		;
> +	} else {
> +		host_sgpio->pcb->cr0 =
> +			SET_ENABLE(host_sgpio->pcb->cr0);
> +		csr = 0;
> +		csr = SET_CMD(csr, cmd);
> +		outb(csr, (unsigned long)host_sgpio->pcsr);
> +	}
> +	spin_unlock(&sgpio_share->lock);
> +	return 1;
> +}
> +
> +static u8 nv_sgpio_update_led(struct nv_sgpio_led *led, u8 *on_off)
> +{
> +	u8 need_update = 0;
> +
> +	if (led->force_off > 0) {
> +		led->force_off--;
> +	} else if (led->flags.recent_activity ^ led->flags.last_state) {
> +		*on_off = led->flags.recent_activity;
> +		led->flags.last_state = led->flags.recent_activity;
> +		need_update = 1;
> +	} else if ((led->flags.recent_activity == NV_ON) &&
> +		   (led->flags.last_state == NV_ON) &&
> +		   (led->last_cons_active >= NV_SGPIO_MAX_ACTIVITY_ON)) {
> +		*on_off = NV_OFF;
> +		led->flags.last_state = NV_OFF;
> +		led->force_off = NV_SGPIO_MIN_FORCE_OFF;
> +		need_update = 1;
> +	}
> +
> +	if (*on_off == NV_ON)
> +		led->last_cons_active++;
> +	else
> +		led->last_cons_active = 0;
> +
> +	led->flags.recent_activity = NV_OFF;
> +	return need_update;
> +}
> +
> +static void nv_sgpio_reset(u8  *pcsr)
> +{
> +	u8 csr;
> +
> +	csr = inb((unsigned long)pcsr);
> +	if (GET_SGPIO_STATUS(csr) == NV_SGPIO_STATE_RESET) {
> +		csr = 0;
> +		csr = SET_CMD(csr, NV_SGPIO_CMD_RESET);
> +		outb(csr, (unsigned long)pcsr);
> +	}
> +	csr = 0;
> +	csr = SET_CMD(csr, NV_SGPIO_CMD_READ_PARAMS);
> +	outb(csr, (unsigned long)pcsr);
> +}
> +
> +static void nv_sgpio_host_cleanup(struct nv_host_priv *host)
> +{
> +	u8 csr;
> +	struct nv_host_sgpio *host_sgpio;
> +	struct nv_sgpio_host_share *sgpio_share;
> +
> +	if (!host)
> +		return;

Can this happen?

> +	host_sgpio = &host->host_sgpio;
> +	if (!host_sgpio->share_index)
> +		return;
> +
> +	sgpio_share = &nv_sgpio_share[host_sgpio->share_index];
> +	if (host_sgpio->flags.sgpio_enabled) {
> +		spin_lock(&sgpio_share->lock);
> +		host_sgpio->pcb->cr0 = SET_ENABLE(host_sgpio->pcb->cr0);
> +		csr = 0;
> +		csr = SET_CMD(csr, NV_SGPIO_CMD_WRITE_DATA);
> +		outb(csr, (unsigned long)host_sgpio->pcsr);
> +		spin_unlock(&sgpio_share->lock);
> +
> +		if (timer_pending(&sgpio_share->timer))
> +			del_timer(&sgpio_share->timer);

The timer could actually be executing on another CPU right now, in
which case I think we crash?

An unconditional del_timer_sync() might be safer.  Please check.

> +		host_sgpio->flags.sgpio_enabled = 0;
> +		host_sgpio->pcb->scratch_space = 0;
> +	}
> +}
> +
> +static void nv_sgpio_clear_all_leds(struct ata_port *ap)
> +{
> +	struct nv_port_priv *port = ap->private_data;
> +	struct nv_host_priv *host;
> +	u8 host_offset, port_offset;
> +	struct nv_host_sgpio *host_sgpio;
> +	struct nv_sgpio_host_share *sgpio_share;
> +
> +	if (!port || !ap->host)
> +		return;
> +	if (!ap->host->private_data)
> +		return;

Can all of these happen?

> +	host = ap->host->private_data;

missed a typecast :)

> +	host_sgpio = &host->host_sgpio;
> +	if (!host_sgpio->share_index)
> +		return;
> +
> +	sgpio_share = &nv_sgpio_share[host_sgpio->share_index];
> +	if (!host_sgpio->flags.sgpio_enabled)
> +		return;
> +
> +	host_offset = nv_sgpio_tx_host_offset(ap->host);
> +	port_offset = nv_sgpio_tx_port_offset(ap);
> +
> +	spin_lock(&sgpio_share->lock);
> +	host_sgpio->pcb->tx[host_offset].tx_port[port_offset] = 0;
> +	host_sgpio->flags.need_update = 1;
> +	spin_unlock(&sgpio_share->lock);
> +}
> +
>  static int __init nv_init(void)
>  {
>  	return pci_register_driver(&nv_pci_driver);

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