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SubjectRe: RESEND: [PATCH] libata-sff: Fix oops reported in kerneloops.org for pnp devices with no ctl
And this is how a revised one would look.

libata-sff: Fix oops reported in kerneloops.org for pnp devices with no ctl

From: Alan Cox <alan@redhat.com>


---
drivers/ata/libata-sff.c | 88 +++++++++++++++++++++++++++++++++++++++------
drivers/ata/pata_icside.c | 2 +
include/linux/libata.h | 14 +------
3 files changed, 78 insertions(+), 26 deletions(-)

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 3c2d228..7958da7 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -256,6 +256,73 @@ u8 ata_sff_altstatus(struct ata_port *ap)
}

/**
+ * ata_sff_irq_status - Check if the device is busy
+ * @ap: port where the device is
+ *
+ * Determine if the port is currently busy. Uses altstatus
+ * if available in order to avoid clearing shared IRQ status
+ * when finding an IRQ source. Non ctl capable devices don't
+ * share interrupt lines fortunately for us.
+ *
+ * LOCKING:
+ * Inherited from caller.
+ */
+static u8 ata_sff_irq_status(struct ata_port *ap)
+{
+ u8 status;
+
+ if (ap->ops->sff_check_altstatus || ap->ioaddr.altstatus_addr) {
+ status = ata_sff_altstatus(ap);
+ /* Not us: We are busy */
+ if (status & ATA_BUSY)
+ return status;
+ }
+ /* Clear INTRQ latch */
+ status = ata_sff_check_status(ap);
+ return status;
+}
+
+/**
+ * ata_sff_sync - Flush writes
+ * @ap: Port to wait for.
+ *
+ * CAUTION:
+ * If we have an mmio device with no ctl and no altstatus
+ * method this will fail. No such devices are known to exist.
+ *
+ * LOCKING:
+ * Inherited from caller.
+ */
+
+static void ata_sff_sync(struct ata_port *ap)
+{
+ if (ap->ops->sff_check_altstatus)
+ ap->ops->sff_check_altstatus(ap);
+ else if (ap->ioaddr.altstatus_addr)
+ ioread8(ap->ioaddr.altstatus_addr);
+ ndelay(400);
+}
+
+/**
+ * ata_sff_pause - Flush writes and wait 400nS
+ * @ap: Port to wait for.
+ *
+ * CAUTION:
+ * If we have an mmio device with no ctl and no altstatus
+ * method this will fail. No such devices are known to exist.
+ *
+ * LOCKING:
+ * Inherited from caller.
+ */
+
+void ata_sff_pause(struct ata_port *ap)
+{
+ ata_sff_sync(ap);
+ ndelay(400);
+}
+
+
+/**
* ata_sff_busy_sleep - sleep until BSY clears, or timeout
* @ap: port containing status register to be polled
* @tmout_pat: impatience timeout
@@ -742,7 +809,7 @@ static void ata_pio_sectors(struct ata_queued_cmd *qc)
} else
ata_pio_sector(qc);

- ata_sff_altstatus(qc->ap); /* flush */
+ ata_sff_sync(qc->ap); /* flush */
}

/**
@@ -763,7 +830,7 @@ static void atapi_send_cdb(struct ata_port *ap, struct ata_queued_cmd *qc)
WARN_ON(qc->dev->cdb_len < 12);

ap->ops->sff_data_xfer(qc->dev, qc->cdb, qc->dev->cdb_len, 1);
- ata_sff_altstatus(ap); /* flush */
+ ata_sff_pause(ap);

switch (qc->tf.protocol) {
case ATAPI_PROT_PIO:
@@ -905,7 +972,7 @@ static void atapi_pio_bytes(struct ata_queued_cmd *qc)

if (unlikely(__atapi_pio_bytes(qc, bytes)))
goto err_out;
- ata_sff_altstatus(ap); /* flush */
+ ata_sff_pause(ap); /* flush */

return;

@@ -1489,14 +1556,10 @@ inline unsigned int ata_sff_host_intr(struct ata_port *ap,
goto idle_irq;
}

- /* check altstatus */
- status = ata_sff_altstatus(ap);
- if (status & ATA_BUSY)
- goto idle_irq;

- /* check main status, clearing INTRQ */
- status = ap->ops->sff_check_status(ap);
- if (unlikely(status & ATA_BUSY))
+ /* check main status, clearing INTRQ if needed */
+ status = ata_sff_irq_status(ap);
+ if (status & ATA_BUSY)
goto idle_irq;

/* ack bmdma irq events */
@@ -2030,7 +2093,7 @@ void ata_sff_error_handler(struct ata_port *ap)
ap->ops->bmdma_stop(qc);
}

- ata_sff_altstatus(ap);
+ ata_sff_sync(ap); /* FIXME: We don't need this */
ap->ops->sff_check_status(ap);
ap->ops->sff_irq_clear(ap);

@@ -2203,7 +2266,7 @@ void ata_bmdma_stop(struct ata_queued_cmd *qc)
mmio + ATA_DMA_CMD);

/* one-PIO-cycle guaranteed wait, per spec, for HDMA1:0 transition */
- ata_sff_altstatus(ap); /* dummy read */
+ ata_sff_sync(ap); /* dummy read */
}

/**
@@ -2723,6 +2786,7 @@ EXPORT_SYMBOL_GPL(ata_sff_dumb_qc_prep);
EXPORT_SYMBOL_GPL(ata_sff_dev_select);
EXPORT_SYMBOL_GPL(ata_sff_check_status);
EXPORT_SYMBOL_GPL(ata_sff_altstatus);
+EXPORT_SYMBOL_GPL(ata_sff_pause);
EXPORT_SYMBOL_GPL(ata_sff_busy_sleep);
EXPORT_SYMBOL_GPL(ata_sff_wait_ready);
EXPORT_SYMBOL_GPL(ata_sff_tf_load);
diff --git a/drivers/ata/pata_icside.c b/drivers/ata/pata_icside.c
index 1713843..bc685cd 100644
--- a/drivers/ata/pata_icside.c
+++ b/drivers/ata/pata_icside.c
@@ -269,7 +269,7 @@ static void pata_icside_bmdma_stop(struct ata_queued_cmd *qc)

disable_dma(state->dma);

- /* see ata_bmdma_stop */
+ /* see ata_bmdma_stop: we know we have a ctl port in this case */
ata_sff_altstatus(ap);
}

diff --git a/include/linux/libata.h b/include/linux/libata.h
index 4a92fba..8eb5022 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1435,6 +1435,7 @@ extern void ata_sff_qc_prep(struct ata_queued_cmd *qc);
extern void ata_sff_dumb_qc_prep(struct ata_queued_cmd *qc);
extern void ata_sff_dev_select(struct ata_port *ap, unsigned int device);
extern u8 ata_sff_check_status(struct ata_port *ap);
+extern void ata_sff_pause(struct ata_port *ap);
extern u8 ata_sff_altstatus(struct ata_port *ap);
extern int ata_sff_busy_sleep(struct ata_port *ap,
unsigned long timeout_pat, unsigned long timeout);
@@ -1496,19 +1497,6 @@ extern int ata_pci_sff_init_one(struct pci_dev *pdev,
#endif /* CONFIG_PCI */

/**
- * ata_sff_pause - Flush writes and pause 400 nanoseconds.
- * @ap: Port to wait for.
- *
- * LOCKING:
- * Inherited from caller.
- */
-static inline void ata_sff_pause(struct ata_port *ap)
-{
- ata_sff_altstatus(ap);
- ndelay(400);
-}
-
-/**
* ata_sff_busy_wait - Wait for a port status register
* @ap: Port to wait for.
* @bits: bits that must be clear

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