libata: implement and use ata_noop_irq_clear()

->irq_clear() is used to clear IRQ bit of a SFF controller and isn't
useful for drivers which don't use libata SFF HSM implementation.
However, it's a required callback and many drivers implement their own
noop version as placeholder.  This patch implements ata_noop_irq_clear
and use it to replace those custom placeholders.

Also, SFF drivers which don't support BMDMA don't need to use
ata_bmdma_irq_clear().  It becomes noop if BMDMA address isn't
initialized.  Convert them to use ata_noop_irq_clear().

Signed-off-by: Tejun Heo <htejun@gmail.com>

drivers/ata/ahci.c

@@ -244,7 +244,6 @@ static int ahci_scr_read(struct ata_port *ap, unsigned int sc_reg, u32 *val);
 static int ahci_scr_write(struct ata_port *ap, unsigned int sc_reg, u32 val);
 static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);
 static unsigned int ahci_qc_issue(struct ata_queued_cmd *qc);
-static void ahci_irq_clear(struct ata_port *ap);
 static int ahci_port_start(struct ata_port *ap);
 static void ahci_port_stop(struct ata_port *ap);
 static void ahci_tf_read(struct ata_port *ap, struct ata_taskfile *tf);
@@ -307,7 +306,7 @@ static const struct ata_port_operations ahci_ops = {
 	.qc_prep		= ahci_qc_prep,
 	.qc_issue		= ahci_qc_issue,
 
-	.irq_clear		= ahci_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 
 	.scr_read		= ahci_scr_read,
 	.scr_write		= ahci_scr_write,
@@ -343,7 +342,7 @@ static const struct ata_port_operations ahci_vt8251_ops = {
 	.qc_prep		= ahci_qc_prep,
 	.qc_issue		= ahci_qc_issue,
 
-	.irq_clear		= ahci_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 
 	.scr_read		= ahci_scr_read,
 	.scr_write		= ahci_scr_write,
@@ -377,7 +376,7 @@ static const struct ata_port_operations ahci_p5wdh_ops = {
 	.qc_prep		= ahci_qc_prep,
 	.qc_issue		= ahci_qc_issue,
 
-	.irq_clear		= ahci_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 
 	.scr_read		= ahci_scr_read,
 	.scr_write		= ahci_scr_write,
@@ -1769,11 +1768,6 @@ static void ahci_port_intr(struct ata_port *ap)
 	}
 }
 
-static void ahci_irq_clear(struct ata_port *ap)
-{
-	/* TODO */
-}
-
 static irqreturn_t ahci_interrupt(int irq, void *dev_instance)
 {
 	struct ata_host *host = dev_instance;

drivers/ata/libata-core.c

@@ -7824,6 +7824,7 @@ EXPORT_SYMBOL_GPL(ata_noop_qc_prep);
 EXPORT_SYMBOL_GPL(ata_bmdma_setup);
 EXPORT_SYMBOL_GPL(ata_bmdma_start);
 EXPORT_SYMBOL_GPL(ata_bmdma_irq_clear);
+EXPORT_SYMBOL_GPL(ata_noop_irq_clear);
 EXPORT_SYMBOL_GPL(ata_bmdma_status);
 EXPORT_SYMBOL_GPL(ata_bmdma_stop);
 EXPORT_SYMBOL_GPL(ata_bmdma_freeze);

drivers/ata/libata-sff.c

@@ -302,6 +302,14 @@ void ata_bmdma_irq_clear(struct ata_port *ap)
 	iowrite8(ioread8(mmio + ATA_DMA_STATUS), mmio + ATA_DMA_STATUS);
 }
 
+/**
+ *	ata_noop_irq_clear - Noop placeholder for irq_clear
+ *	@ap: Port associated with this ATA transaction.
+ */
+void ata_noop_irq_clear(struct ata_port *ap)
+{
+}
+
 /**
  *	ata_bmdma_status - Read PCI IDE BMDMA status
  *	@ap: Port associated with this ATA transaction.

drivers/ata/pata_ali.c

@@ -380,7 +380,7 @@ static struct ata_port_operations ali_early_port_ops = {
 	.data_xfer	= ata_data_xfer,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pata_at32.c

@@ -166,11 +166,6 @@ static void pata_at32_set_piomode(struct ata_port *ap, struct ata_device *adev)
 	}
 }
 
-static void pata_at32_irq_clear(struct ata_port *ap)
-{
-	/* No DMA controller yet */
-}
-
 static struct scsi_host_template at32_sht = {
 	.module			= THIS_MODULE,
 	.name			= DRV_NAME,
@@ -208,7 +203,7 @@ static struct ata_port_operations at32_port_ops = {
 
 	.data_xfer		= ata_data_xfer,
 
-	.irq_clear		= pata_at32_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.port_start		= ata_sff_port_start,

drivers/ata/pata_icside.c

@@ -322,11 +322,6 @@ static struct scsi_host_template pata_icside_sht = {
 	.bios_param		= ata_std_bios_param,
 };
 
-/* wish this was exported from libata-core */
-static void ata_dummy_noret(struct ata_port *port)
-{
-}
-
 static void pata_icside_postreset(struct ata_link *link, unsigned int *classes)
 {
 	struct ata_port *ap = link->ap;
@@ -380,7 +375,7 @@ static struct ata_port_operations pata_icside_port_ops = {
 	.error_handler		= pata_icside_error_handler,
 	.post_internal_cmd	= pata_icside_bmdma_stop,
 
-	.irq_clear		= ata_dummy_noret,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.bmdma_stop		= pata_icside_bmdma_stop,

drivers/ata/pata_isapnp.c

@@ -55,7 +55,7 @@ static struct ata_port_operations isapnp_port_ops = {
 
 	.data_xfer	= ata_data_xfer,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pata_ixp4xx_cf.c

@@ -126,7 +126,7 @@ static struct ata_port_operations ixp4xx_port_ops = {
 	.cable_detect		= ata_cable_40wire,
 
 	.irq_handler		= ata_interrupt,
-	.irq_clear		= ata_bmdma_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.port_start		= ata_port_start,

drivers/ata/pata_legacy.c

@@ -252,7 +252,7 @@ static struct ata_port_operations simple_port_ops = {
 	.data_xfer	= ata_data_xfer_noirq,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -279,7 +279,7 @@ static struct ata_port_operations legacy_port_ops = {
 	.data_xfer	= ata_data_xfer_noirq,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -393,7 +393,7 @@ static struct ata_port_operations pdc20230_port_ops = {
 	.data_xfer	= pdc_data_xfer_vlb,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -447,7 +447,7 @@ static struct ata_port_operations ht6560a_port_ops = {
 	.data_xfer	= ata_data_xfer,	/* Check vlb/noirq */
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -512,7 +512,7 @@ static struct ata_port_operations ht6560b_port_ops = {
 	.data_xfer	= ata_data_xfer,    /* FIXME: Check 32bit and noirq */
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -633,7 +633,7 @@ static struct ata_port_operations opti82c611a_port_ops = {
 	.data_xfer	= ata_data_xfer,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -765,7 +765,7 @@ static struct ata_port_operations opti82c46x_port_ops = {
 	.data_xfer	= ata_data_xfer,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -950,7 +950,7 @@ static struct ata_port_operations qdi6500_port_ops = {
 	.data_xfer	= vlb32_data_xfer,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -977,7 +977,7 @@ static struct ata_port_operations qdi6580_port_ops = {
 	.data_xfer	= vlb32_data_xfer,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -1004,7 +1004,7 @@ static struct ata_port_operations qdi6580dp_port_ops = {
 	.data_xfer	= vlb32_data_xfer,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -1095,7 +1095,7 @@ static struct ata_port_operations winbond_port_ops = {
 
 	.data_xfer	= vlb32_data_xfer,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pata_mpc52xx.c

@@ -296,7 +296,7 @@ static struct ata_port_operations mpc52xx_ata_port_ops = {
 	.qc_prep		= ata_qc_prep,
 	.qc_issue		= ata_qc_issue_prot,
 	.data_xfer		= ata_data_xfer,
-	.irq_clear		= ata_bmdma_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 	.port_start		= ata_port_start,
 };

drivers/ata/pata_mpiix.c

@@ -187,7 +187,7 @@ static struct ata_port_operations mpiix_port_ops = {
 	.qc_issue	= mpiix_qc_issue_prot,
 	.data_xfer	= ata_data_xfer,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pata_ns87410.c

@@ -182,7 +182,7 @@ static struct ata_port_operations ns87410_port_ops = {
 	.data_xfer	= ata_data_xfer,
 
 	.irq_handler	= ata_interrupt,
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pata_pcmcia.c

@@ -164,7 +164,7 @@ static struct ata_port_operations pcmcia_port_ops = {
 
 	.data_xfer	= ata_data_xfer_noirq,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -189,7 +189,7 @@ static struct ata_port_operations pcmcia_8bit_port_ops = {
 
 	.data_xfer	= ata_data_xfer_8bit,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pata_platform.c

@@ -86,7 +86,7 @@ static struct ata_port_operations pata_platform_port_ops = {
 
 	.data_xfer		= ata_data_xfer_noirq,
 
-	.irq_clear		= ata_bmdma_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.port_start		= ata_dummy_ret0,

drivers/ata/pata_qdi.c

@@ -191,7 +191,7 @@ static struct ata_port_operations qdi6500_port_ops = {
 
 	.data_xfer	= qdi_data_xfer,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,
@@ -217,7 +217,7 @@ static struct ata_port_operations qdi6580_port_ops = {
 
 	.data_xfer	= qdi_data_xfer,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pata_rb500_cf.c

@@ -117,10 +117,6 @@ static irqreturn_t rb500_pata_irq_handler(int irq, void *dev_instance)
 	return IRQ_HANDLED;
 }
 
-static void rb500_pata_irq_clear(struct ata_port *ap)
-{
-}
-
 static int rb500_pata_port_start(struct ata_port *ap)
 {
 	return 0;
@@ -144,7 +140,7 @@ static struct ata_port_operations rb500_pata_port_ops = {
 	.error_handler		= ata_bmdma_error_handler,
 
 	.irq_handler		= rb500_pata_irq_handler,
-	.irq_clear		= rb500_pata_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.port_start		= rb500_pata_port_start,

drivers/ata/pata_winbond.c

@@ -159,7 +159,7 @@ static struct ata_port_operations winbond_port_ops = {
 
 	.data_xfer	= winbond_data_xfer,
 
-	.irq_clear	= ata_bmdma_irq_clear,
+	.irq_clear	= ata_noop_irq_clear,
 	.irq_on		= ata_irq_on,
 
 	.port_start	= ata_sff_port_start,

drivers/ata/pdc_adma.c

@@ -138,7 +138,6 @@ static unsigned int adma_qc_issue(struct ata_queued_cmd *qc);
 static int adma_check_atapi_dma(struct ata_queued_cmd *qc);
 static void adma_bmdma_stop(struct ata_queued_cmd *qc);
 static u8 adma_bmdma_status(struct ata_port *ap);
-static void adma_irq_clear(struct ata_port *ap);
 static void adma_freeze(struct ata_port *ap);
 static void adma_thaw(struct ata_port *ap);
 static void adma_error_handler(struct ata_port *ap);
@@ -174,7 +173,7 @@ static const struct ata_port_operations adma_ata_ops = {
 	.freeze			= adma_freeze,
 	.thaw			= adma_thaw,
 	.error_handler		= adma_error_handler,
-	.irq_clear		= adma_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 	.port_start		= adma_port_start,
 	.port_stop		= adma_port_stop,
@@ -223,11 +222,6 @@ static u8 adma_bmdma_status(struct ata_port *ap)
 	return 0;
 }
 
-static void adma_irq_clear(struct ata_port *ap)
-{
-	/* nothing */
-}
-
 static void adma_reset_engine(struct ata_port *ap)
 {
 	void __iomem *chan = ADMA_PORT_REGS(ap);

drivers/ata/sata_fsl.c

@@ -933,11 +933,6 @@ static void sata_fsl_post_internal_cmd(struct ata_queued_cmd *qc)
 	}
 }
 
-static void sata_fsl_irq_clear(struct ata_port *ap)
-{
-	/* unused */
-}
-
 static void sata_fsl_error_intr(struct ata_port *ap)
 {
 	struct ata_link *link = &ap->link;
@@ -1223,7 +1218,7 @@ static const struct ata_port_operations sata_fsl_ops = {
 
 	.qc_prep = sata_fsl_qc_prep,
 	.qc_issue = sata_fsl_qc_issue,
-	.irq_clear = sata_fsl_irq_clear,
+	.irq_clear = ata_noop_irq_clear,
 
 	.scr_read = sata_fsl_scr_read,
 	.scr_write = sata_fsl_scr_write,

drivers/ata/sata_inic162x.c

@@ -266,11 +266,6 @@ static u8 inic_bmdma_status(struct ata_port *ap)
 	return ATA_DMA_INTR;
 }
 
-static void inic_irq_clear(struct ata_port *ap)
-{
-	/* noop */
-}
-
 static void inic_host_intr(struct ata_port *ap)
 {
 	void __iomem *port_base = inic_port_base(ap);
@@ -555,7 +550,7 @@ static struct ata_port_operations inic_port_ops = {
 	.bmdma_stop		= inic_bmdma_stop,
 	.bmdma_status		= inic_bmdma_status,
 
-	.irq_clear		= inic_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.qc_prep	 	= ata_qc_prep,

drivers/ata/sata_mv.c

@@ -461,7 +461,6 @@ struct mv_hw_ops {
 	void (*reset_bus)(struct ata_host *host, void __iomem *mmio);
 };
 
-static void mv_irq_clear(struct ata_port *ap);
 static int mv_scr_read(struct ata_port *ap, unsigned int sc_reg_in, u32 *val);
 static int mv_scr_write(struct ata_port *ap, unsigned int sc_reg_in, u32 val);
 static int mv5_scr_read(struct ata_port *ap, unsigned int sc_reg_in, u32 *val);
@@ -564,7 +563,7 @@ static const struct ata_port_operations mv5_ops = {
 	.qc_issue		= mv_qc_issue,
 	.data_xfer		= ata_data_xfer,
 
-	.irq_clear		= mv_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.error_handler		= mv_error_handler,
@@ -592,7 +591,7 @@ static const struct ata_port_operations mv6_ops = {
 	.qc_issue		= mv_qc_issue,
 	.data_xfer		= ata_data_xfer,
 
-	.irq_clear		= mv_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.error_handler		= mv_error_handler,
@@ -620,7 +619,7 @@ static const struct ata_port_operations mv_iie_ops = {
 	.qc_issue		= mv_qc_issue,
 	.data_xfer		= ata_data_xfer,
 
-	.irq_clear		= mv_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 
 	.error_handler		= mv_error_handler,
@@ -801,10 +800,6 @@ static inline int mv_get_hc_count(unsigned long port_flags)
 	return ((port_flags & MV_FLAG_DUAL_HC) ? 2 : 1);
 }
 
-static void mv_irq_clear(struct ata_port *ap)
-{
-}
-
 static void mv_set_edma_ptrs(void __iomem *port_mmio,
 			     struct mv_host_priv *hpriv,
 			     struct mv_port_priv *pp)

drivers/ata/sata_qstor.c

@@ -121,7 +121,6 @@ static unsigned int qs_qc_issue(struct ata_queued_cmd *qc);
 static int qs_check_atapi_dma(struct ata_queued_cmd *qc);
 static void qs_bmdma_stop(struct ata_queued_cmd *qc);
 static u8 qs_bmdma_status(struct ata_port *ap);
-static void qs_irq_clear(struct ata_port *ap);
 static void qs_freeze(struct ata_port *ap);
 static void qs_thaw(struct ata_port *ap);
 static void qs_error_handler(struct ata_port *ap);
@@ -157,7 +156,7 @@ static const struct ata_port_operations qs_ata_ops = {
 	.freeze			= qs_freeze,
 	.thaw			= qs_thaw,
 	.error_handler		= qs_error_handler,
-	.irq_clear		= qs_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 	.irq_on			= ata_irq_on,
 	.scr_read		= qs_scr_read,
 	.scr_write		= qs_scr_write,
@@ -211,11 +210,6 @@ static u8 qs_bmdma_status(struct ata_port *ap)
 	return 0;
 }
 
-static void qs_irq_clear(struct ata_port *ap)
-{
-	/* nothing */
-}
-
 static inline void qs_enter_reg_mode(struct ata_port *ap)
 {
 	u8 __iomem *chan = qs_mmio_base(ap->host) + (ap->port_no * 0x4000);

drivers/ata/sata_sil24.c

@@ -348,7 +348,6 @@ static void sil24_tf_read(struct ata_port *ap, struct ata_taskfile *tf);
 static int sil24_qc_defer(struct ata_queued_cmd *qc);
 static void sil24_qc_prep(struct ata_queued_cmd *qc);
 static unsigned int sil24_qc_issue(struct ata_queued_cmd *qc);
-static void sil24_irq_clear(struct ata_port *ap);
 static void sil24_pmp_attach(struct ata_port *ap);
 static void sil24_pmp_detach(struct ata_port *ap);
 static void sil24_freeze(struct ata_port *ap);
@@ -416,7 +415,7 @@ static const struct ata_port_operations sil24_ops = {
 	.qc_prep		= sil24_qc_prep,
 	.qc_issue		= sil24_qc_issue,
 
-	.irq_clear		= sil24_irq_clear,
+	.irq_clear		= ata_noop_irq_clear,
 
 	.scr_read		= sil24_scr_read,
 	.scr_write		= sil24_scr_write,
@@ -921,11 +920,6 @@ static unsigned int sil24_qc_issue(struct ata_queued_cmd *qc)
 	return 0;
 }
 
-static void sil24_irq_clear(struct ata_port *ap)
-{
-	/* unused */
-}
-
 static void sil24_pmp_attach(struct ata_port *ap)
 {
 	sil24_config_pmp(ap, 1);

include/linux/libata.h

@@ -896,6 +896,7 @@ extern void ata_bmdma_start(struct ata_queued_cmd *qc);
 extern void ata_bmdma_stop(struct ata_queued_cmd *qc);
 extern u8   ata_bmdma_status(struct ata_port *ap);
 extern void ata_bmdma_irq_clear(struct ata_port *ap);
+extern void ata_noop_irq_clear(struct ata_port *ap);
 extern void ata_bmdma_freeze(struct ata_port *ap);
 extern void ata_bmdma_thaw(struct ata_port *ap);
 extern void ata_bmdma_drive_eh(struct ata_port *ap, ata_prereset_fn_t prereset,