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SubjectRe: Kernel Summit request for Discussion of future of ATA (libata) and IDE
Alan Cox wrote:
>> I guess that bit doesn't really make any difference with remotely modern
>> drives, then.. Could we make that ata_id_has_dword_io check always
>> return true if ata_id_is_ata returns true and only check word 48 if not?
>
> I suspect (but need to dig further) that ata_id_has_dword_io should only
> be called by pata_legacy.
>
>> I saw Willy Tarreau's patch from February for this, I agree that we
>> should likely use a separate data_xfer method for 32-bit transfer (or if
>> enough controllers should support 32-bit, then just make it be the
>> default and make a separate 16-bit only function for those that don't),
>> rather than punting the decision to the user with hdparm.
>
> Definitely.
>
>> You mentioned in the thread for Willy's patch that "some
>> controllers have quirky rules for 32bit xfers" - any details anywhere?
>
> There are two main ones
>
> - Some controllers only support 32bit I/O for a multiple of 32bit values
> [sometimes 'unless the fifo is disabled']. I'd have to go back over the
> docs but I think the AMD may be one of those
> - Some controllers (VLB generally) require a magic sequence before the
> transfer. You'll see that in the pata_legacy bits.

Here's my first cut at it. Compile tested only. This sets most controllers
to use 32-bit PIO except for those which could potentially be on a real ISA
or other 16-bit bus. It's a bit non-obvious what to do with some of the
drivers, so input is welcome.

This implementation doesn't check the ata_id_has_dword_io at all, since it
would only make a difference on controllers where we don't really want to
use it anyway.

It seems like regardless of whether we do 32-bit by default or not the 32-bit
data_xfer function should be added to libata core as we have several drivers
which duplicate the same code currently..

Signed-off-by: Robert Hancock <hancockr@shaw.ca>
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 304fdc6..acb65a9 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -673,13 +673,14 @@ static inline void ata_tf_to_host(struct ata_port *ap,
}

/**
- * ata_sff_data_xfer - Transfer data by PIO
+ * ata_sff_data_xfer_16bit - Transfer data by PIO
* @dev: device to target
* @buf: data buffer
* @buflen: buffer length
* @rw: read/write
*
- * Transfer data from/to the device data register by PIO.
+ * Transfer data from/to the device data register by PIO using only
+ * 16-bit transfers.
*
* LOCKING:
* Inherited from caller.
@@ -687,7 +688,7 @@ static inline void ata_tf_to_host(struct ata_port *ap,
* RETURNS:
* Bytes consumed.
*/
-unsigned int ata_sff_data_xfer(struct ata_device *dev, unsigned char *buf,
+unsigned int ata_sff_data_xfer_16bit(struct ata_device *dev, unsigned char *buf,
unsigned int buflen, int rw)
{
struct ata_port *ap = dev->link->ap;
@@ -719,6 +720,51 @@ unsigned int ata_sff_data_xfer(struct ata_device *dev, unsigned char *buf,
}

/**
+ * ata_sff_data_xfer - Transfer data by PIO
+ * @dev: device to target
+ * @buf: data buffer
+ * @buflen: buffer length
+ * @rw: read/write
+ *
+ * Transfer data from/to the device data register by PIO.
+ *
+ * LOCKING:
+ * Inherited from caller.
+ *
+ * RETURNS:
+ * Bytes consumed.
+ */
+unsigned int ata_sff_data_xfer(struct ata_device *dev, unsigned char *buf,
+ unsigned int buflen, int rw)
+{
+ struct ata_port *ap = dev->link->ap;
+ void __iomem *data_addr = ap->ioaddr.data_addr;
+ unsigned int words = buflen >> 2;
+ unsigned int slop = buflen & 3;
+
+ /* Transfer multiple of 4 bytes */
+ if (rw == READ)
+ ioread32_rep(data_addr, buf, words);
+ else
+ iowrite32_rep(data_addr, buf, words);
+
+ /* Transfer trailing 1 byte, if any. */
+ if (unlikely(slop)) {
+ __le32 pad = 0;
+ if (rw == READ) {
+ pad = cpu_to_le32(ioread32(ap->ioaddr.data_addr));
+ memcpy(buf + buflen - slop, &pad, slop);
+ } else {
+ memcpy(&pad, buf + buflen - slop, slop);
+ iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
+ }
+ buflen += 4 - slop;
+ }
+
+ return buflen;
+}
+
+/**
* ata_sff_data_xfer_noirq - Transfer data by PIO
* @dev: device to target
* @buf: data buffer
@@ -748,6 +794,36 @@ unsigned int ata_sff_data_xfer_noirq(struct ata_device *dev, unsigned char *buf,
}

/**
+ * ata_sff_data_xfer_noirq_16bit - Transfer data by PIO
+ * @dev: device to target
+ * @buf: data buffer
+ * @buflen: buffer length
+ * @rw: read/write
+ *
+ * Transfer data from/to the device data register by PIO. Do the
+ * transfer with interrupts disabled using only 16-bit transfers.
+ *
+ * LOCKING:
+ * Inherited from caller.
+ *
+ * RETURNS:
+ * Bytes consumed.
+ */
+unsigned int ata_sff_data_xfer_noirq_16bit(struct ata_device *dev,
+ unsigned char *buf,
+ unsigned int buflen, int rw)
+{
+ unsigned long flags;
+ unsigned int consumed;
+
+ local_irq_save(flags);
+ consumed = ata_sff_data_xfer_16bit(dev, buf, buflen, rw);
+ local_irq_restore(flags);
+
+ return consumed;
+}
+
+/**
* ata_pio_sector - Transfer a sector of data.
* @qc: Command on going
*
@@ -2827,7 +2903,9 @@ EXPORT_SYMBOL_GPL(ata_sff_tf_load);
EXPORT_SYMBOL_GPL(ata_sff_tf_read);
EXPORT_SYMBOL_GPL(ata_sff_exec_command);
EXPORT_SYMBOL_GPL(ata_sff_data_xfer);
+EXPORT_SYMBOL_GPL(ata_sff_data_xfer_16bit);
EXPORT_SYMBOL_GPL(ata_sff_data_xfer_noirq);
+EXPORT_SYMBOL_GPL(ata_sff_data_xfer_noirq_16bit);
EXPORT_SYMBOL_GPL(ata_sff_irq_on);
EXPORT_SYMBOL_GPL(ata_sff_irq_clear);
EXPORT_SYMBOL_GPL(ata_sff_hsm_move);
diff --git a/drivers/ata/pata_at32.c b/drivers/ata/pata_at32.c
index 82fb6e2..aa90b19 100644
--- a/drivers/ata/pata_at32.c
+++ b/drivers/ata/pata_at32.c
@@ -173,6 +173,7 @@ static struct scsi_host_template at32_sht = {
static struct ata_port_operations at32_port_ops = {
.inherits = &ata_sff_port_ops,
.cable_detect = ata_cable_40wire,
+ .sff_data_xfer = ata_sff_data_xfer_16bit,
.set_piomode = pata_at32_set_piomode,
};

diff --git a/drivers/ata/pata_icside.c b/drivers/ata/pata_icside.c
index cf9e984..a1f09ca 100644
--- a/drivers/ata/pata_icside.c
+++ b/drivers/ata/pata_icside.c
@@ -336,7 +336,7 @@ static struct ata_port_operations pata_icside_port_ops = {
.inherits = &ata_sff_port_ops,
/* no need to build any PRD tables for DMA */
.qc_prep = ata_noop_qc_prep,
- .sff_data_xfer = ata_sff_data_xfer_noirq,
+ .sff_data_xfer = ata_sff_data_xfer_noirq_16bit,
.bmdma_setup = pata_icside_bmdma_setup,
.bmdma_start = pata_icside_bmdma_start,
.bmdma_stop = pata_icside_bmdma_stop,
diff --git a/drivers/ata/pata_isapnp.c b/drivers/ata/pata_isapnp.c
index 6a111ba..6f38f76 100644
--- a/drivers/ata/pata_isapnp.c
+++ b/drivers/ata/pata_isapnp.c
@@ -26,6 +26,7 @@ static struct scsi_host_template isapnp_sht = {
static struct ata_port_operations isapnp_port_ops = {
.inherits = &ata_sff_port_ops,
.cable_detect = ata_cable_40wire,
+ .sff_data_xfer = ata_sff_data_xfer_16bit,
};

/**
diff --git a/drivers/ata/pata_legacy.c b/drivers/ata/pata_legacy.c
index bc037ff..d919934 100644
--- a/drivers/ata/pata_legacy.c
+++ b/drivers/ata/pata_legacy.c
@@ -226,12 +226,12 @@ static const struct ata_port_operations legacy_base_port_ops = {

static struct ata_port_operations simple_port_ops = {
.inherits = &legacy_base_port_ops,
- .sff_data_xfer = ata_sff_data_xfer_noirq,
+ .sff_data_xfer = ata_sff_data_xfer_noirq_16bit,
};

static struct ata_port_operations legacy_port_ops = {
.inherits = &legacy_base_port_ops,
- .sff_data_xfer = ata_sff_data_xfer_noirq,
+ .sff_data_xfer = ata_sff_data_xfer_noirq_16bit,
.set_mode = legacy_set_mode,
};

@@ -286,39 +286,18 @@ static void pdc20230_set_piomode(struct ata_port *ap, struct ata_device *adev)
static unsigned int pdc_data_xfer_vlb(struct ata_device *dev,
unsigned char *buf, unsigned int buflen, int rw)
{
- if (ata_id_has_dword_io(dev->id)) {
- struct ata_port *ap = dev->link->ap;
- int slop = buflen & 3;
- unsigned long flags;
+ unsigned long flags;

- local_irq_save(flags);
+ local_irq_save(flags);

- /* Perform the 32bit I/O synchronization sequence */
- ioread8(ap->ioaddr.nsect_addr);
- ioread8(ap->ioaddr.nsect_addr);
- ioread8(ap->ioaddr.nsect_addr);
+ /* Perform the 32bit I/O synchronization sequence */
+ ioread8(ap->ioaddr.nsect_addr);
+ ioread8(ap->ioaddr.nsect_addr);
+ ioread8(ap->ioaddr.nsect_addr);

- /* Now the data */
- if (rw == READ)
- ioread32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
- else
- iowrite32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
-
- if (unlikely(slop)) {
- __le32 pad;
- if (rw == READ) {
- pad = cpu_to_le32(ioread32(ap->ioaddr.data_addr));
- memcpy(buf + buflen - slop, &pad, slop);
- } else {
- memcpy(&pad, buf + buflen - slop, slop);
- iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
- }
- buflen += 4 - slop;
- }
- local_irq_restore(flags);
- } else
- buflen = ata_sff_data_xfer_noirq(dev, buf, buflen, rw);
+ buflen = ata_sff_data_xfer(dev, buf, buflen, rw);

+ local_irq_restore(flags);
return buflen;
}

@@ -733,33 +712,6 @@ static unsigned int qdi_qc_issue(struct ata_queued_cmd *qc)
return ata_sff_qc_issue(qc);
}

-static unsigned int vlb32_data_xfer(struct ata_device *adev, unsigned char *buf,
- unsigned int buflen, int rw)
-{
- struct ata_port *ap = adev->link->ap;
- int slop = buflen & 3;
-
- if (ata_id_has_dword_io(adev->id)) {
- if (rw == WRITE)
- iowrite32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
- else
- ioread32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
-
- if (unlikely(slop)) {
- __le32 pad;
- if (rw == WRITE) {
- memcpy(&pad, buf + buflen - slop, slop);
- iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
- } else {
- pad = cpu_to_le32(ioread32(ap->ioaddr.data_addr));
- memcpy(buf + buflen - slop, &pad, slop);
- }
- }
- return (buflen + 3) & ~3;
- } else
- return ata_sff_data_xfer(adev, buf, buflen, rw);
-}
-
static int qdi_port(struct platform_device *dev,
struct legacy_probe *lp, struct legacy_data *ld)
{
@@ -773,19 +725,19 @@ static struct ata_port_operations qdi6500_port_ops = {
.inherits = &legacy_base_port_ops,
.set_piomode = qdi6500_set_piomode,
.qc_issue = qdi_qc_issue,
- .sff_data_xfer = vlb32_data_xfer,
+ .sff_data_xfer = ata_sff_data_xfer,
};

static struct ata_port_operations qdi6580_port_ops = {
.inherits = &legacy_base_port_ops,
.set_piomode = qdi6580_set_piomode,
- .sff_data_xfer = vlb32_data_xfer,
+ .sff_data_xfer = ata_sff_data_xfer,
};

static struct ata_port_operations qdi6580dp_port_ops = {
.inherits = &legacy_base_port_ops,
.set_piomode = qdi6580dp_set_piomode,
- .sff_data_xfer = vlb32_data_xfer,
+ .sff_data_xfer = ata_sff_data_xfer,
};

static DEFINE_SPINLOCK(winbond_lock);
@@ -856,7 +808,7 @@ static int winbond_port(struct platform_device *dev,
static struct ata_port_operations winbond_port_ops = {
.inherits = &legacy_base_port_ops,
.set_piomode = winbond_set_piomode,
- .sff_data_xfer = vlb32_data_xfer,
+ .sff_data_xfer = ata_sff_data_xfer,
};

static struct legacy_controller controllers[] = {
diff --git a/drivers/ata/pata_mpc52xx.c b/drivers/ata/pata_mpc52xx.c
index a9e8273..0ab2c8e 100644
--- a/drivers/ata/pata_mpc52xx.c
+++ b/drivers/ata/pata_mpc52xx.c
@@ -265,6 +265,7 @@ static struct ata_port_operations mpc52xx_ata_port_ops = {
.cable_detect = ata_cable_40wire,
.set_piomode = mpc52xx_ata_set_piomode,
.post_internal_cmd = ATA_OP_NULL,
+ .sff_data_xfer = ata_sff_data_xfer_16bit,
};

static int __devinit
diff --git a/drivers/ata/pata_pcmcia.c b/drivers/ata/pata_pcmcia.c
index 41b4361..8cb4923 100644
--- a/drivers/ata/pata_pcmcia.c
+++ b/drivers/ata/pata_pcmcia.c
@@ -133,7 +133,7 @@ static struct scsi_host_template pcmcia_sht = {

static struct ata_port_operations pcmcia_port_ops = {
.inherits = &ata_sff_port_ops,
- .sff_data_xfer = ata_sff_data_xfer_noirq,
+ .sff_data_xfer = ata_sff_data_xfer_noirq_16bit,
.cable_detect = ata_cable_40wire,
.set_mode = pcmcia_set_mode,
};
diff --git a/drivers/ata/pata_platform.c b/drivers/ata/pata_platform.c
index 8f65ad6..3310eb0 100644
--- a/drivers/ata/pata_platform.c
+++ b/drivers/ata/pata_platform.c
@@ -52,7 +52,7 @@ static struct scsi_host_template pata_platform_sht = {

static struct ata_port_operations pata_platform_port_ops = {
.inherits = &ata_sff_port_ops,
- .sff_data_xfer = ata_sff_data_xfer_noirq,
+ .sff_data_xfer = ata_sff_data_xfer_noirq_16bit,
.cable_detect = ata_cable_unknown,
.set_mode = pata_platform_set_mode,
.port_start = ATA_OP_NULL,
diff --git a/drivers/ata/pata_qdi.c b/drivers/ata/pata_qdi.c
index 63b7a1c..36cc778 100644
--- a/drivers/ata/pata_qdi.c
+++ b/drivers/ata/pata_qdi.c
@@ -124,35 +124,6 @@ static unsigned int qdi_qc_issue(struct ata_queued_cmd *qc)
return ata_sff_qc_issue(qc);
}

-static unsigned int qdi_data_xfer(struct ata_device *dev, unsigned char *buf,
- unsigned int buflen, int rw)
-{
- if (ata_id_has_dword_io(dev->id)) {
- struct ata_port *ap = dev->link->ap;
- int slop = buflen & 3;
-
- if (rw == READ)
- ioread32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
- else
- iowrite32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
-
- if (unlikely(slop)) {
- __le32 pad;
- if (rw == READ) {
- pad = cpu_to_le32(ioread32(ap->ioaddr.data_addr));
- memcpy(buf + buflen - slop, &pad, slop);
- } else {
- memcpy(&pad, buf + buflen - slop, slop);
- iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
- }
- buflen += 4 - slop;
- }
- } else
- buflen = ata_sff_data_xfer(dev, buf, buflen, rw);
-
- return buflen;
-}
-
static struct scsi_host_template qdi_sht = {
ATA_PIO_SHT(DRV_NAME),
};
@@ -160,7 +131,6 @@ static struct scsi_host_template qdi_sht = {
static struct ata_port_operations qdi6500_port_ops = {
.inherits = &ata_sff_port_ops,
.qc_issue = qdi_qc_issue,
- .sff_data_xfer = qdi_data_xfer,
.cable_detect = ata_cable_40wire,
.set_piomode = qdi6500_set_piomode,
};
diff --git a/drivers/ata/pata_winbond.c b/drivers/ata/pata_winbond.c
index a7606b0..56f5f8e 100644
--- a/drivers/ata/pata_winbond.c
+++ b/drivers/ata/pata_winbond.c
@@ -92,42 +92,12 @@ static void winbond_set_piomode(struct ata_port *ap, struct ata_device *adev)
}


-static unsigned int winbond_data_xfer(struct ata_device *dev,
- unsigned char *buf, unsigned int buflen, int rw)
-{
- struct ata_port *ap = dev->link->ap;
- int slop = buflen & 3;
-
- if (ata_id_has_dword_io(dev->id)) {
- if (rw == READ)
- ioread32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
- else
- iowrite32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
-
- if (unlikely(slop)) {
- __le32 pad;
- if (rw == READ) {
- pad = cpu_to_le32(ioread32(ap->ioaddr.data_addr));
- memcpy(buf + buflen - slop, &pad, slop);
- } else {
- memcpy(&pad, buf + buflen - slop, slop);
- iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
- }
- buflen += 4 - slop;
- }
- } else
- buflen = ata_sff_data_xfer(dev, buf, buflen, rw);
-
- return buflen;
-}
-
static struct scsi_host_template winbond_sht = {
ATA_PIO_SHT(DRV_NAME),
};

static struct ata_port_operations winbond_port_ops = {
.inherits = &ata_sff_port_ops,
- .sff_data_xfer = winbond_data_xfer,
.cable_detect = ata_cable_40wire,
.set_piomode = winbond_set_piomode,
};
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 06b8033..643328a 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1481,8 +1481,12 @@ extern void ata_sff_exec_command(struct ata_port *ap,
const struct ata_taskfile *tf);
extern unsigned int ata_sff_data_xfer(struct ata_device *dev,
unsigned char *buf, unsigned int buflen, int rw);
+extern unsigned int ata_sff_data_xfer_16bit(struct ata_device *dev,
+ unsigned char *buf, unsigned int buflen, int rw);
extern unsigned int ata_sff_data_xfer_noirq(struct ata_device *dev,
unsigned char *buf, unsigned int buflen, int rw);
+extern unsigned int ata_sff_data_xfer_noirq_16bit(struct ata_device *dev,
+ unsigned char *buf, unsigned int buflen, int rw);
extern u8 ata_sff_irq_on(struct ata_port *ap);
extern void ata_sff_irq_clear(struct ata_port *ap);
extern int ata_sff_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,


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