[PATCH 2/6] esp_scsi: Track residual for PIO transfers

[PATCH 2/6] esp_scsi: Track residual for PIO transfers

[Finn Thain]

If a target disconnects during a PIO data transfer the command may
fail when the target reconnects:

scsi host1: DMA length is zero!
scsi host1: cur adr[04380000] len[00000000]

The scsi bus is then reset. This happens because the residual reached
zero before the transfer was completed.

The usual residual calculation relies on the Transfer Count registers
which works for DMA transfers but not for PIO transfers. Fix the problem
by storing the PIO transfer residual and using that to correctly
calculate bytes_sent.

Fixes: 6fe07aaffbf0
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/esp_scsi.c | 1 +
 drivers/scsi/esp_scsi.h | 2 ++
 drivers/scsi/mac_esp.c  | 2 ++
 3 files changed, 5 insertions(+)

diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index c3fc34b9964d..9e5d3f7d29ae 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -1338,6 +1338,7 @@ static int esp_data_bytes_sent(struct esp *esp, struct esp_cmd_entry *ent,
 
 	bytes_sent = esp->data_dma_len;
 	bytes_sent -= ecount;
+	bytes_sent -= esp->send_cmd_residual;
 
 	/*
 	 * The am53c974 has a DMA 'pecularity'. The doc states:
diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
index 8163dca2071b..db4b6ea94caa 100644
--- a/drivers/scsi/esp_scsi.h
+++ b/drivers/scsi/esp_scsi.h
@@ -540,6 +540,8 @@ struct esp {
 
 	void			*dma;
 	int			dmarev;
+
+	int			send_cmd_residual;
 };
 
 /* A front-end driver for the ESP chip should do the following in
diff --git a/drivers/scsi/mac_esp.c b/drivers/scsi/mac_esp.c
index eb551f3cc471..71879f2207e0 100644
--- a/drivers/scsi/mac_esp.c
+++ b/drivers/scsi/mac_esp.c
@@ -427,6 +427,8 @@ static void mac_esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
 			scsi_esp_cmd(esp, ESP_CMD_TI);
 		}
 	}
+
+	esp->send_cmd_residual = esp_count;
 }
 
 static int mac_esp_irq_pending(struct esp *esp)
-- 
2.16.4

[PATCH 4/6] esp_scsi: Eliminate ESP_FLAG_DOING_SLOWCMD

[Finn Thain]

The concept of a 'slow command' as it appears in esp_scsi is confusing
because it could refer to an ESP command or a SCSI command. It turns out
that it refers to a particular ESP select command which the driver also
tracks as 'ESP_SELECT_MSGOUT'. For readability, it is better to use the
terminology from the datasheets.

The global ESP_FLAG_DOING_SLOWCMD flag is redundant anyway, as it can be
inferred from esp->select_state. Remove the ESP_FLAG_DOING_SLOWCMD cruft
and just use a boolean local variable.

Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/esp_scsi.c | 57 ++++++++++++++++++++-----------------------------
 drivers/scsi/esp_scsi.h |  3 +--
 2 files changed, 24 insertions(+), 36 deletions(-)

diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index b7c41aa9927c..6ccaf818357e 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -478,17 +478,6 @@ static void esp_restore_pointers(struct esp *esp, struct esp_cmd_entry *ent)
 	spriv->tot_residue = ent->saved_tot_residue;
 }
 
-static void esp_check_command_len(struct esp *esp, struct scsi_cmnd *cmd)
-{
-	if (cmd->cmd_len == 6 ||
-	    cmd->cmd_len == 10 ||
-	    cmd->cmd_len == 12) {
-		esp->flags &= ~ESP_FLAG_DOING_SLOWCMD;
-	} else {
-		esp->flags |= ESP_FLAG_DOING_SLOWCMD;
-	}
-}
-
 static void esp_write_tgt_config3(struct esp *esp, int tgt)
 {
 	if (esp->rev > ESP100A) {
@@ -721,6 +710,7 @@ static void esp_maybe_execute_command(struct esp *esp)
 	struct scsi_device *dev;
 	struct scsi_cmnd *cmd;
 	struct esp_cmd_entry *ent;
+	bool select_and_stop = false;
 	int tgt, lun, i;
 	u32 val, start_cmd;
 	u8 *p;
@@ -752,7 +742,8 @@ static void esp_maybe_execute_command(struct esp *esp)
 	esp_map_dma(esp, cmd);
 	esp_save_pointers(esp, ent);
 
-	esp_check_command_len(esp, cmd);
+	if (!(cmd->cmd_len == 6 || cmd->cmd_len == 10 || cmd->cmd_len == 12))
+		select_and_stop = true;
 
 	p = esp->command_block;
 
@@ -793,9 +784,9 @@ static void esp_maybe_execute_command(struct esp *esp)
 			tp->flags &= ~ESP_TGT_CHECK_NEGO;
 		}
 
-		/* Process it like a slow command.  */
-		if (tp->flags & (ESP_TGT_NEGO_WIDE | ESP_TGT_NEGO_SYNC))
-			esp->flags |= ESP_FLAG_DOING_SLOWCMD;
+		/* If there are multiple message bytes, use Select and Stop */
+		if (esp->msg_out_len)
+			select_and_stop = true;
 	}
 
 build_identify:
@@ -808,23 +799,10 @@ static void esp_maybe_execute_command(struct esp *esp)
 		/* ESP100 lacks select w/atn3 command, use select
 		 * and stop instead.
 		 */
-		esp->flags |= ESP_FLAG_DOING_SLOWCMD;
+		select_and_stop = true;
 	}
 
-	if (!(esp->flags & ESP_FLAG_DOING_SLOWCMD)) {
-		start_cmd = ESP_CMD_SELA;
-		if (ent->tag[0]) {
-			*p++ = ent->tag[0];
-			*p++ = ent->tag[1];
-
-			start_cmd = ESP_CMD_SA3;
-		}
-
-		for (i = 0; i < cmd->cmd_len; i++)
-			*p++ = cmd->cmnd[i];
-
-		esp->select_state = ESP_SELECT_BASIC;
-	} else {
+	if (select_and_stop) {
 		esp->cmd_bytes_left = cmd->cmd_len;
 		esp->cmd_bytes_ptr = &cmd->cmnd[0];
 
@@ -839,6 +817,19 @@ static void esp_maybe_execute_command(struct esp *esp)
 
 		start_cmd = ESP_CMD_SELAS;
 		esp->select_state = ESP_SELECT_MSGOUT;
+	} else {
+		start_cmd = ESP_CMD_SELA;
+		if (ent->tag[0]) {
+			*p++ = ent->tag[0];
+			*p++ = ent->tag[1];
+
+			start_cmd = ESP_CMD_SA3;
+		}
+
+		for (i = 0; i < cmd->cmd_len; i++)
+			*p++ = cmd->cmnd[i];
+
+		esp->select_state = ESP_SELECT_BASIC;
 	}
 	val = tgt;
 	if (esp->rev == FASHME)
@@ -1248,7 +1239,6 @@ static int esp_finish_select(struct esp *esp)
 			esp_unmap_dma(esp, cmd);
 			esp_free_lun_tag(ent, cmd->device->hostdata);
 			tp->flags &= ~(ESP_TGT_NEGO_SYNC | ESP_TGT_NEGO_WIDE);
-			esp->flags &= ~ESP_FLAG_DOING_SLOWCMD;
 			esp->cmd_bytes_ptr = NULL;
 			esp->cmd_bytes_left = 0;
 		} else {
@@ -1299,9 +1289,8 @@ static int esp_finish_select(struct esp *esp)
 				esp_flush_fifo(esp);
 		}
 
-		/* If we are doing a slow command, negotiation, etc.
-		 * we'll do the right thing as we transition to the
-		 * next phase.
+		/* If we are doing a Select And Stop command, negotiation, etc.
+		 * we'll do the right thing as we transition to the next phase.
 		 */
 		esp_event(esp, ESP_EVENT_CHECK_PHASE);
 		return 0;
diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
index db4b6ea94caa..d0c032803749 100644
--- a/drivers/scsi/esp_scsi.h
+++ b/drivers/scsi/esp_scsi.h
@@ -490,7 +490,6 @@ struct esp {
 	u32			flags;
 #define ESP_FLAG_DIFFERENTIAL	0x00000001
 #define ESP_FLAG_RESETTING	0x00000002
-#define ESP_FLAG_DOING_SLOWCMD	0x00000004
 #define ESP_FLAG_WIDE_CAPABLE	0x00000008
 #define ESP_FLAG_QUICKIRQ_CHECK	0x00000010
 #define ESP_FLAG_DISABLE_SYNC	0x00000020
@@ -532,7 +531,7 @@ struct esp {
 	u32			min_period;
 	u32			radelay;
 
-	/* Slow command state.  */
+	/* ESP_CMD_SELAS command state */
 	u8			*cmd_bytes_ptr;
 	int			cmd_bytes_left;
 
-- 
2.16.4

[PATCH 5/6] esp_scsi: De-duplicate PIO routines

[Finn Thain]

As a temporary measure, the code to implement PIO transfers was
duplicated in zorro_esp and mac_esp. Now that this code has stabilized,
move it into the core driver to eliminate the duplication.

This replaces the inline assembler with more portable writesb() calls.
Optimizing the m68k writesb() implementation is a separate patch.

Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/esp_scsi.c  | 126 +++++++++++++++++++++++++
 drivers/scsi/esp_scsi.h  |   5 +
 drivers/scsi/mac_esp.c   | 173 ++---------------------------------
 drivers/scsi/zorro_esp.c | 232 +++++++----------------------------------------
 4 files changed, 171 insertions(+), 365 deletions(-)

diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 6ccaf818357e..646701fc22a4 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -2776,3 +2776,129 @@ MODULE_PARM_DESC(esp_debug,
 
 module_init(esp_init);
 module_exit(esp_exit);
+
+#if IS_ENABLED(CONFIG_SCSI_MAC_ESP) || IS_ENABLED(CONFIG_SCSI_ZORRO_ESP)
+static inline unsigned int esp_wait_for_fifo(struct esp *esp)
+{
+	int i = 500000;
+
+	do {
+		unsigned int fbytes = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;
+
+		if (fbytes)
+			return fbytes;
+
+		udelay(2);
+	} while (--i);
+
+	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
+	return 0;
+}
+
+static inline int esp_wait_for_intr(struct esp *esp)
+{
+	int i = 500000;
+
+	do {
+		esp->sreg = esp_read8(ESP_STATUS);
+		if (esp->sreg & ESP_STAT_INTR)
+			return 0;
+
+		udelay(2);
+	} while (--i);
+
+	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
+	return 1;
+}
+
+#define ESP_FIFO_SIZE 16
+
+void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
+		      u32 dma_count, int write, u8 cmd)
+{
+	u8 phase = esp->sreg & ESP_STAT_PMASK;
+
+	cmd &= ~ESP_CMD_DMA;
+	esp->send_cmd_error = 0;
+
+	if (write) {
+		u8 *dst = (u8 *)addr;
+		u8 mask = ~(phase == ESP_MIP ? ESP_INTR_FDONE : ESP_INTR_BSERV);
+
+		scsi_esp_cmd(esp, cmd);
+
+		while (1) {
+			if (!esp_wait_for_fifo(esp))
+				break;
+
+			*dst++ = esp_read8(ESP_FDATA);
+			--esp_count;
+
+			if (!esp_count)
+				break;
+
+			if (esp_wait_for_intr(esp)) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			if ((esp->sreg & ESP_STAT_PMASK) != phase)
+				break;
+
+			esp->ireg = esp_read8(ESP_INTRPT);
+			if (esp->ireg & mask) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			if (phase == ESP_MIP)
+				scsi_esp_cmd(esp, ESP_CMD_MOK);
+
+			scsi_esp_cmd(esp, ESP_CMD_TI);
+		}
+	} else {
+		unsigned int n = ESP_FIFO_SIZE;
+		u8 *src = (u8 *)addr;
+
+		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
+
+		if (n > esp_count)
+			n = esp_count;
+		writesb(esp->fifo_reg, src, n);
+		src += n;
+		esp_count -= n;
+
+		scsi_esp_cmd(esp, cmd);
+
+		while (esp_count) {
+			if (esp_wait_for_intr(esp)) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			if ((esp->sreg & ESP_STAT_PMASK) != phase)
+				break;
+
+			esp->ireg = esp_read8(ESP_INTRPT);
+			if (esp->ireg & ~ESP_INTR_BSERV) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			n = ESP_FIFO_SIZE -
+			    (esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES);
+
+			if (n > esp_count)
+				n = esp_count;
+			writesb(esp->fifo_reg, src, n);
+			src += n;
+			esp_count -= n;
+
+			scsi_esp_cmd(esp, ESP_CMD_TI);
+		}
+	}
+
+	esp->send_cmd_residual = esp_count;
+}
+EXPORT_SYMBOL(esp_send_pio_cmd);
+#endif
diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
index d0c032803749..2590e5eda595 100644
--- a/drivers/scsi/esp_scsi.h
+++ b/drivers/scsi/esp_scsi.h
@@ -431,6 +431,7 @@ struct esp_driver_ops {
 struct esp {
 	void __iomem		*regs;
 	void __iomem		*dma_regs;
+	u8 __iomem		*fifo_reg;
 
 	const struct esp_driver_ops *ops;
 
@@ -540,6 +541,7 @@ struct esp {
 	void			*dma;
 	int			dmarev;
 
+	int			send_cmd_error;
 	int			send_cmd_residual;
 };
 
@@ -581,4 +583,7 @@ extern void scsi_esp_unregister(struct esp *);
 extern irqreturn_t scsi_esp_intr(int, void *);
 extern void scsi_esp_cmd(struct esp *, u8);
 
+extern void esp_send_pio_cmd(struct esp *esp, u32 dma_addr, u32 esp_count,
+			     u32 dma_count, int write, u8 cmd);
+
 #endif /* !(_ESP_SCSI_H) */
diff --git a/drivers/scsi/mac_esp.c b/drivers/scsi/mac_esp.c
index 71879f2207e0..1becf6a195a2 100644
--- a/drivers/scsi/mac_esp.c
+++ b/drivers/scsi/mac_esp.c
@@ -52,7 +52,6 @@ struct mac_esp_priv {
 	struct esp *esp;
 	void __iomem *pdma_regs;
 	void __iomem *pdma_io;
-	int error;
 };
 static struct esp *esp_chips[2];
 static DEFINE_SPINLOCK(esp_chips_lock);
@@ -120,12 +119,11 @@ static void mac_esp_dma_invalidate(struct esp *esp)
 
 static int mac_esp_dma_error(struct esp *esp)
 {
-	return MAC_ESP_GET_PRIV(esp)->error;
+	return esp->send_cmd_error;
 }
 
 static inline int mac_esp_wait_for_empty_fifo(struct esp *esp)
 {
-	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);
 	int i = 500000;
 
 	do {
@@ -140,7 +138,7 @@ static inline int mac_esp_wait_for_empty_fifo(struct esp *esp)
 
 	printk(KERN_ERR PFX "FIFO is not empty (sreg %02x)\n",
 	       esp_read8(ESP_STATUS));
-	mep->error = 1;
+	esp->send_cmd_error = 1;
 	return 1;
 }
 
@@ -166,7 +164,7 @@ static inline int mac_esp_wait_for_dreq(struct esp *esp)
 
 	printk(KERN_ERR PFX "PDMA timeout (sreg %02x)\n",
 	       esp_read8(ESP_STATUS));
-	mep->error = 1;
+	esp->send_cmd_error = 1;
 	return 1;
 }
 
@@ -233,7 +231,7 @@ static void mac_esp_send_pdma_cmd(struct esp *esp, u32 addr, u32 esp_count,
 {
 	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);
 
-	mep->error = 0;
+	esp->send_cmd_error = 0;
 
 	if (!write)
 		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
@@ -271,166 +269,6 @@ static void mac_esp_send_pdma_cmd(struct esp *esp, u32 addr, u32 esp_count,
 	} while (esp_count);
 }
 
-/*
- * Programmed IO routines follow.
- */
-
-static inline unsigned int mac_esp_wait_for_fifo(struct esp *esp)
-{
-	int i = 500000;
-
-	do {
-		unsigned int fbytes = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;
-
-		if (fbytes)
-			return fbytes;
-
-		udelay(2);
-	} while (--i);
-
-	printk(KERN_ERR PFX "FIFO is empty (sreg %02x)\n",
-	       esp_read8(ESP_STATUS));
-	return 0;
-}
-
-static inline int mac_esp_wait_for_intr(struct esp *esp)
-{
-	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);
-	int i = 500000;
-
-	do {
-		esp->sreg = esp_read8(ESP_STATUS);
-		if (esp->sreg & ESP_STAT_INTR)
-			return 0;
-
-		udelay(2);
-	} while (--i);
-
-	printk(KERN_ERR PFX "IRQ timeout (sreg %02x)\n", esp->sreg);
-	mep->error = 1;
-	return 1;
-}
-
-#define MAC_ESP_PIO_LOOP(operands, reg1) \
-	asm volatile ( \
-	     "1:     moveb " operands " \n" \
-	     "       subqw #1,%1        \n" \
-	     "       jbne 1b            \n" \
-	     : "+a" (addr), "+r" (reg1) \
-	     : "a" (fifo))
-
-#define MAC_ESP_PIO_FILL(operands, reg1) \
-	asm volatile ( \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       moveb " operands " \n" \
-	     "       subqw #8,%1        \n" \
-	     "       subqw #8,%1        \n" \
-	     : "+a" (addr), "+r" (reg1) \
-	     : "a" (fifo))
-
-#define MAC_ESP_FIFO_SIZE 16
-
-static void mac_esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
-				 u32 dma_count, int write, u8 cmd)
-{
-	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);
-	u8 __iomem *fifo = esp->regs + ESP_FDATA * 16;
-	u8 phase = esp->sreg & ESP_STAT_PMASK;
-
-	cmd &= ~ESP_CMD_DMA;
-	mep->error = 0;
-
-	if (write) {
-		u8 *dst = (u8 *)addr;
-		u8 mask = ~(phase == ESP_MIP ? ESP_INTR_FDONE : ESP_INTR_BSERV);
-
-		scsi_esp_cmd(esp, cmd);
-
-		while (1) {
-			if (!mac_esp_wait_for_fifo(esp))
-				break;
-
-			*dst++ = esp_read8(ESP_FDATA);
-			--esp_count;
-
-			if (!esp_count)
-				break;
-
-			if (mac_esp_wait_for_intr(esp))
-				break;
-
-			if ((esp->sreg & ESP_STAT_PMASK) != phase)
-				break;
-
-			esp->ireg = esp_read8(ESP_INTRPT);
-			if (esp->ireg & mask) {
-				mep->error = 1;
-				break;
-			}
-
-			if (phase == ESP_MIP)
-				scsi_esp_cmd(esp, ESP_CMD_MOK);
-
-			scsi_esp_cmd(esp, ESP_CMD_TI);
-		}
-	} else {
-		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
-
-		if (esp_count >= MAC_ESP_FIFO_SIZE)
-			MAC_ESP_PIO_FILL("%0@+,%2@", esp_count);
-		else
-			MAC_ESP_PIO_LOOP("%0@+,%2@", esp_count);
-
-		scsi_esp_cmd(esp, cmd);
-
-		while (esp_count) {
-			unsigned int n;
-
-			if (mac_esp_wait_for_intr(esp))
-				break;
-
-			if ((esp->sreg & ESP_STAT_PMASK) != phase)
-				break;
-
-			esp->ireg = esp_read8(ESP_INTRPT);
-			if (esp->ireg & ~ESP_INTR_BSERV) {
-				mep->error = 1;
-				break;
-			}
-
-			n = MAC_ESP_FIFO_SIZE -
-			    (esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES);
-			if (n > esp_count)
-				n = esp_count;
-
-			if (n == MAC_ESP_FIFO_SIZE) {
-				MAC_ESP_PIO_FILL("%0@+,%2@", esp_count);
-			} else {
-				esp_count -= n;
-				MAC_ESP_PIO_LOOP("%0@+,%2@", n);
-			}
-
-			scsi_esp_cmd(esp, ESP_CMD_TI);
-		}
-	}
-
-	esp->send_cmd_residual = esp_count;
-}
-
 static int mac_esp_irq_pending(struct esp *esp)
 {
 	if (esp_read8(ESP_STATUS) & ESP_STAT_INTR)
@@ -553,6 +391,7 @@ static int esp_mac_probe(struct platform_device *dev)
 		mep->pdma_regs = NULL;
 		break;
 	}
+	esp->fifo_reg = esp->regs + ESP_FDATA * 16;
 
 	esp->ops = &mac_esp_ops;
 	if (mep->pdma_io == NULL) {
@@ -560,7 +399,7 @@ static int esp_mac_probe(struct platform_device *dev)
 		esp_write8(0, ESP_TCLOW);
 		esp_write8(0, ESP_TCMED);
 		esp->flags = ESP_FLAG_DISABLE_SYNC;
-		mac_esp_ops.send_dma_cmd = mac_esp_send_pio_cmd;
+		mac_esp_ops.send_dma_cmd = esp_send_pio_cmd;
 	} else {
 		printk(KERN_INFO PFX "using PDMA for controller %d\n", dev->id);
 	}
diff --git a/drivers/scsi/zorro_esp.c b/drivers/scsi/zorro_esp.c
index be79127db594..88e2bbc509ba 100644
--- a/drivers/scsi/zorro_esp.c
+++ b/drivers/scsi/zorro_esp.c
@@ -9,8 +9,6 @@
  *
  * Copyright (C) 2013 Tuomas Vainikka (tuomas.vainikka@aalto.fi) for
  *               Blizzard 1230 DMA and probe function fixes
- *
- * Copyright (C) 2017 Finn Thain for PIO code from Mac ESP driver adapted here
  */
 /*
  * ZORRO bus code from:
@@ -159,7 +157,6 @@ struct fastlane_dma_registers {
 struct zorro_esp_priv {
 	struct esp *esp;		/* our ESP instance - for Scsi_host* */
 	void __iomem *board_base;	/* virtual address (Zorro III board) */
-	int error;			/* PIO error flag */
 	int zorro3;			/* board is Zorro III */
 	unsigned char ctrl_data;	/* shadow copy of ctrl_reg */
 };
@@ -274,192 +271,29 @@ static void fastlane_esp_dma_invalidate(struct esp *esp)
 	z_writel(0, zep->board_base);
 }
 
-/*
- * Programmed IO routines follow.
- */
-
-static inline unsigned int zorro_esp_wait_for_fifo(struct esp *esp)
-{
-	int i = 500000;
-
-	do {
-		unsigned int fbytes = zorro_esp_read8(esp, ESP_FFLAGS)
-							& ESP_FF_FBYTES;
-
-		if (fbytes)
-			return fbytes;
-
-		udelay(2);
-	} while (--i);
-
-	pr_err("FIFO is empty (sreg %02x)\n",
-	       zorro_esp_read8(esp, ESP_STATUS));
-	return 0;
-}
-
-static inline int zorro_esp_wait_for_intr(struct esp *esp)
-{
-	struct zorro_esp_priv *zep = dev_get_drvdata(esp->dev);
-	int i = 500000;
-
-	do {
-		esp->sreg = zorro_esp_read8(esp, ESP_STATUS);
-		if (esp->sreg & ESP_STAT_INTR)
-			return 0;
-
-		udelay(2);
-	} while (--i);
-
-	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
-	zep->error = 1;
-	return 1;
-}
-
-/*
- * PIO macros as used in mac_esp.c.
- * Note that addr and fifo arguments are local-scope variables declared
- * in zorro_esp_send_pio_cmd(), the macros are only used in that function,
- * and addr and fifo are referenced in each use of the macros so there
- * is no need to pass them as macro parameters.
- */
-#define ZORRO_ESP_PIO_LOOP(operands, reg1) \
-	asm volatile ( \
-	     "1:     moveb " operands "\n" \
-	     "       subqw #1,%1       \n" \
-	     "       jbne 1b           \n" \
-	     : "+a" (addr), "+r" (reg1) \
-	     : "a" (fifo));
-
-#define ZORRO_ESP_PIO_FILL(operands, reg1) \
-	asm volatile ( \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       moveb " operands "\n" \
-	     "       subqw #8,%1       \n" \
-	     "       subqw #8,%1       \n" \
-	     : "+a" (addr), "+r" (reg1) \
-	     : "a" (fifo));
-
-#define ZORRO_ESP_FIFO_SIZE 16
-
-static void zorro_esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
-				 u32 dma_count, int write, u8 cmd)
-{
-	struct zorro_esp_priv *zep = dev_get_drvdata(esp->dev);
-	u8 __iomem *fifo = esp->regs + ESP_FDATA * 16;
-	u8 phase = esp->sreg & ESP_STAT_PMASK;
-
-	cmd &= ~ESP_CMD_DMA;
-
-	if (write) {
-		u8 *dst = (u8 *)addr;
-		u8 mask = ~(phase == ESP_MIP ? ESP_INTR_FDONE : ESP_INTR_BSERV);
-
-		scsi_esp_cmd(esp, cmd);
-
-		while (1) {
-			if (!zorro_esp_wait_for_fifo(esp))
-				break;
-
-			*dst++ = zorro_esp_read8(esp, ESP_FDATA);
-			--esp_count;
-
-			if (!esp_count)
-				break;
-
-			if (zorro_esp_wait_for_intr(esp))
-				break;
-
-			if ((esp->sreg & ESP_STAT_PMASK) != phase)
-				break;
-
-			esp->ireg = zorro_esp_read8(esp, ESP_INTRPT);
-			if (esp->ireg & mask) {
-				zep->error = 1;
-				break;
-			}
-
-			if (phase == ESP_MIP)
-				scsi_esp_cmd(esp, ESP_CMD_MOK);
-
-			scsi_esp_cmd(esp, ESP_CMD_TI);
-		}
-	} else {	/* unused, as long as we only handle MIP here */
-		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
-
-		if (esp_count >= ZORRO_ESP_FIFO_SIZE)
-			ZORRO_ESP_PIO_FILL("%0@+,%2@", esp_count)
-		else
-			ZORRO_ESP_PIO_LOOP("%0@+,%2@", esp_count)
-
-		scsi_esp_cmd(esp, cmd);
-
-		while (esp_count) {
-			unsigned int n;
-
-			if (zorro_esp_wait_for_intr(esp))
-				break;
-
-			if ((esp->sreg & ESP_STAT_PMASK) != phase)
-				break;
-
-			esp->ireg = zorro_esp_read8(esp, ESP_INTRPT);
-			if (esp->ireg & ~ESP_INTR_BSERV) {
-				zep->error = 1;
-				break;
-			}
-
-			n = ZORRO_ESP_FIFO_SIZE -
-			    (zorro_esp_read8(esp, ESP_FFLAGS) & ESP_FF_FBYTES);
-			if (n > esp_count)
-				n = esp_count;
-
-			if (n == ZORRO_ESP_FIFO_SIZE)
-				ZORRO_ESP_PIO_FILL("%0@+,%2@", esp_count)
-			else {
-				esp_count -= n;
-				ZORRO_ESP_PIO_LOOP("%0@+,%2@", n)
-			}
-
-			scsi_esp_cmd(esp, ESP_CMD_TI);
-		}
-	}
-}
-
 /* Blizzard 1230/60 SCSI-IV DMA */
 
 static void zorro_esp_send_blz1230_dma_cmd(struct esp *esp, u32 addr,
 			u32 esp_count, u32 dma_count, int write, u8 cmd)
 {
-	struct zorro_esp_priv *zep = dev_get_drvdata(esp->dev);
 	struct blz1230_dma_registers __iomem *dregs = esp->dma_regs;
 	u8 phase = esp->sreg & ESP_STAT_PMASK;
 
-	zep->error = 0;
 	/*
 	 * Use PIO if transferring message bytes to esp->command_block_dma.
 	 * PIO requires a virtual address, so substitute esp->command_block
 	 * for addr.
 	 */
 	if (phase == ESP_MIP && addr == esp->command_block_dma) {
-		zorro_esp_send_pio_cmd(esp, (u32) esp->command_block,
-					esp_count, dma_count, write, cmd);
+		esp_send_pio_cmd(esp, (u32)esp->command_block, esp_count,
+				 dma_count, write, cmd);
 		return;
 	}
 
+	/* Clear the results of a possible prior esp->ops->send_dma_cmd() */
+	esp->send_cmd_error = 0;
+	esp->send_cmd_residual = 0;
+
 	if (write)
 		/* DMA receive */
 		dma_sync_single_for_device(esp->dev, addr, esp_count,
@@ -493,18 +327,19 @@ static void zorro_esp_send_blz1230_dma_cmd(struct esp *esp, u32 addr,
 static void zorro_esp_send_blz1230II_dma_cmd(struct esp *esp, u32 addr,
 			u32 esp_count, u32 dma_count, int write, u8 cmd)
 {
-	struct zorro_esp_priv *zep = dev_get_drvdata(esp->dev);
 	struct blz1230II_dma_registers __iomem *dregs = esp->dma_regs;
 	u8 phase = esp->sreg & ESP_STAT_PMASK;
 
-	zep->error = 0;
 	/* Use PIO if transferring message bytes to esp->command_block_dma */
 	if (phase == ESP_MIP && addr == esp->command_block_dma) {
-		zorro_esp_send_pio_cmd(esp, (u32) esp->command_block,
-					esp_count, dma_count, write, cmd);
+		esp_send_pio_cmd(esp, (u32)esp->command_block, esp_count,
+				 dma_count, write, cmd);
 		return;
 	}
 
+	esp->send_cmd_error = 0;
+	esp->send_cmd_residual = 0;
+
 	if (write)
 		/* DMA receive */
 		dma_sync_single_for_device(esp->dev, addr, esp_count,
@@ -537,18 +372,19 @@ static void zorro_esp_send_blz1230II_dma_cmd(struct esp *esp, u32 addr,
 static void zorro_esp_send_blz2060_dma_cmd(struct esp *esp, u32 addr,
 			u32 esp_count, u32 dma_count, int write, u8 cmd)
 {
-	struct zorro_esp_priv *zep = dev_get_drvdata(esp->dev);
 	struct blz2060_dma_registers __iomem *dregs = esp->dma_regs;
 	u8 phase = esp->sreg & ESP_STAT_PMASK;
 
-	zep->error = 0;
 	/* Use PIO if transferring message bytes to esp->command_block_dma */
 	if (phase == ESP_MIP && addr == esp->command_block_dma) {
-		zorro_esp_send_pio_cmd(esp, (u32) esp->command_block,
-					esp_count, dma_count, write, cmd);
+		esp_send_pio_cmd(esp, (u32)esp->command_block, esp_count,
+				 dma_count, write, cmd);
 		return;
 	}
 
+	esp->send_cmd_error = 0;
+	esp->send_cmd_residual = 0;
+
 	if (write)
 		/* DMA receive */
 		dma_sync_single_for_device(esp->dev, addr, esp_count,
@@ -586,14 +422,16 @@ static void zorro_esp_send_cyber_dma_cmd(struct esp *esp, u32 addr,
 	u8 phase = esp->sreg & ESP_STAT_PMASK;
 	unsigned char *ctrl_data = &zep->ctrl_data;
 
-	zep->error = 0;
 	/* Use PIO if transferring message bytes to esp->command_block_dma */
 	if (phase == ESP_MIP && addr == esp->command_block_dma) {
-		zorro_esp_send_pio_cmd(esp, (u32) esp->command_block,
-					esp_count, dma_count, write, cmd);
+		esp_send_pio_cmd(esp, (u32)esp->command_block, esp_count,
+				 dma_count, write, cmd);
 		return;
 	}
 
+	esp->send_cmd_error = 0;
+	esp->send_cmd_residual = 0;
+
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
 
@@ -631,18 +469,19 @@ static void zorro_esp_send_cyber_dma_cmd(struct esp *esp, u32 addr,
 static void zorro_esp_send_cyberII_dma_cmd(struct esp *esp, u32 addr,
 			u32 esp_count, u32 dma_count, int write, u8 cmd)
 {
-	struct zorro_esp_priv *zep = dev_get_drvdata(esp->dev);
 	struct cyberII_dma_registers __iomem *dregs = esp->dma_regs;
 	u8 phase = esp->sreg & ESP_STAT_PMASK;
 
-	zep->error = 0;
 	/* Use PIO if transferring message bytes to esp->command_block_dma */
 	if (phase == ESP_MIP && addr == esp->command_block_dma) {
-		zorro_esp_send_pio_cmd(esp, (u32) esp->command_block,
-					esp_count, dma_count, write, cmd);
+		esp_send_pio_cmd(esp, (u32)esp->command_block, esp_count,
+				 dma_count, write, cmd);
 		return;
 	}
 
+	esp->send_cmd_error = 0;
+	esp->send_cmd_residual = 0;
+
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
 
@@ -676,14 +515,16 @@ static void zorro_esp_send_fastlane_dma_cmd(struct esp *esp, u32 addr,
 	u8 phase = esp->sreg & ESP_STAT_PMASK;
 	unsigned char *ctrl_data = &zep->ctrl_data;
 
-	zep->error = 0;
 	/* Use PIO if transferring message bytes to esp->command_block_dma */
 	if (phase == ESP_MIP && addr == esp->command_block_dma) {
-		zorro_esp_send_pio_cmd(esp, (u32) esp->command_block,
-					esp_count, dma_count, write, cmd);
+		esp_send_pio_cmd(esp, (u32)esp->command_block, esp_count,
+				 dma_count, write, cmd);
 		return;
 	}
 
+	esp->send_cmd_error = 0;
+	esp->send_cmd_residual = 0;
+
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
 
@@ -718,14 +559,7 @@ static void zorro_esp_send_fastlane_dma_cmd(struct esp *esp, u32 addr,
 
 static int zorro_esp_dma_error(struct esp *esp)
 {
-	struct zorro_esp_priv *zep = dev_get_drvdata(esp->dev);
-
-	/* check for error in case we've been doing PIO */
-	if (zep->error == 1)
-		return 1;
-
-	/* do nothing - there seems to be no way to check for DMA errors */
-	return 0;
+	return esp->send_cmd_error;
 }
 
 /* per-board ESP driver ops */
@@ -1033,6 +867,8 @@ static int zorro_esp_probe(struct zorro_dev *z,
 		goto fail_unmap_fastlane;
 	}
 
+	esp->fifo_reg = esp->regs + ESP_FDATA * 4;
+
 	/* Check whether a Blizzard 12x0 or CyberstormII really has SCSI */
 	if (zdd->scsi_option) {
 		zorro_esp_write8(esp, (ESP_CONFIG1_PENABLE | 7), ESP_CFG1);
-- 
2.16.4

[PATCH 3/6] esp_scsi: Grant disconnect privilege for untagged commands

[Finn Thain]

A SCSI device is not granted disconnect privilege by an esp_scsi host
unless that device has its simple_tags flag set. However, a device may
support disconnect/reselect and not support command queueing. Allow
these devices to disconnect and improve bus utilization.

Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/esp_scsi.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 9e5d3f7d29ae..b7c41aa9927c 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -800,13 +800,9 @@ static void esp_maybe_execute_command(struct esp *esp)
 
 build_identify:
 	/* If we don't have a lun-data struct yet, we're probing
-	 * so do not disconnect.  Also, do not disconnect unless
-	 * we have a tag on this command.
+	 * so do not disconnect.
 	 */
-	if (lp && (tp->flags & ESP_TGT_DISCONNECT) && ent->tag[0])
-		*p++ = IDENTIFY(1, lun);
-	else
-		*p++ = IDENTIFY(0, lun);
+	*p++ = IDENTIFY(lp && (tp->flags & ESP_TGT_DISCONNECT), lun);
 
 	if (ent->tag[0] && esp->rev == ESP100) {
 		/* ESP100 lacks select w/atn3 command, use select
-- 
2.16.4

[PATCH 1/6] zorro_esp: Limit DMA transfers to 65535 bytes

[Finn Thain]

The core driver, esp_scsi, does not use the ESP_CONFIG2_FENAB bit, so
the chip's Transfer Counter register is only 16 bits wide (not 24).
A larger transfer cannot work and will theoretically result in a failed
command and a "DMA length is zero" error.

Fixes: 3109e5ae0311
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Cc: Michael Schmitz <schmitzmic@gmail.com>
---
 drivers/scsi/zorro_esp.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/scsi/zorro_esp.c b/drivers/scsi/zorro_esp.c
index bb70882e6b56..be79127db594 100644
--- a/drivers/scsi/zorro_esp.c
+++ b/drivers/scsi/zorro_esp.c
@@ -245,7 +245,7 @@ static int fastlane_esp_irq_pending(struct esp *esp)
 static u32 zorro_esp_dma_length_limit(struct esp *esp, u32 dma_addr,
 					u32 dma_len)
 {
-	return dma_len > 0xFFFFFF ? 0xFFFFFF : dma_len;
+	return dma_len > 0xFFFF ? 0xFFFF : dma_len;
 }
 
 static void zorro_esp_reset_dma(struct esp *esp)
@@ -484,7 +484,6 @@ static void zorro_esp_send_blz1230_dma_cmd(struct esp *esp, u32 addr,
 	scsi_esp_cmd(esp, ESP_CMD_DMA);
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
-	zorro_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI);
 
 	scsi_esp_cmd(esp, cmd);
 }
@@ -529,7 +528,6 @@ static void zorro_esp_send_blz1230II_dma_cmd(struct esp *esp, u32 addr,
 	scsi_esp_cmd(esp, ESP_CMD_DMA);
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
-	zorro_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI);
 
 	scsi_esp_cmd(esp, cmd);
 }
@@ -574,7 +572,6 @@ static void zorro_esp_send_blz2060_dma_cmd(struct esp *esp, u32 addr,
 	scsi_esp_cmd(esp, ESP_CMD_DMA);
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
-	zorro_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI);
 
 	scsi_esp_cmd(esp, cmd);
 }
@@ -599,7 +596,6 @@ static void zorro_esp_send_cyber_dma_cmd(struct esp *esp, u32 addr,
 
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
-	zorro_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI);
 
 	if (write) {
 		/* DMA receive */
@@ -649,7 +645,6 @@ static void zorro_esp_send_cyberII_dma_cmd(struct esp *esp, u32 addr,
 
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
-	zorro_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI);
 
 	if (write) {
 		/* DMA receive */
@@ -691,7 +686,6 @@ static void zorro_esp_send_fastlane_dma_cmd(struct esp *esp, u32 addr,
 
 	zorro_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
 	zorro_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
-	zorro_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI);
 
 	if (write) {
 		/* DMA receive */
-- 
2.16.4

[PATCH 6/6] esp_scsi: Optimize PIO loops

[Finn Thain]

Avoid function calls in the inner PIO loops. On a Centris 660av this
improves throughput for sequential read transfers by about 40% and
sequential write by about 10%.

Unfortunately it is not possible to have method calls like esp_write8()
placed inline so this is always going to be slow (even with LTO).

Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/esp_scsi.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 646701fc22a4..9f0e68cd0e99 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -2788,7 +2788,7 @@ static inline unsigned int esp_wait_for_fifo(struct esp *esp)
 		if (fbytes)
 			return fbytes;
 
-		udelay(2);
+		udelay(1);
 	} while (--i);
 
 	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
@@ -2804,7 +2804,7 @@ static inline int esp_wait_for_intr(struct esp *esp)
 		if (esp->sreg & ESP_STAT_INTR)
 			return 0;
 
-		udelay(2);
+		udelay(1);
 	} while (--i);
 
 	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
@@ -2831,7 +2831,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
 			if (!esp_wait_for_fifo(esp))
 				break;
 
-			*dst++ = esp_read8(ESP_FDATA);
+			*dst++ = readb(esp->fifo_reg);
 			--esp_count;
 
 			if (!esp_count)
@@ -2852,15 +2852,15 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
 			}
 
 			if (phase == ESP_MIP)
-				scsi_esp_cmd(esp, ESP_CMD_MOK);
+				esp_write8(ESP_CMD_MOK, ESP_CMD);
 
-			scsi_esp_cmd(esp, ESP_CMD_TI);
+			esp_write8(ESP_CMD_TI, ESP_CMD);
 		}
 	} else {
 		unsigned int n = ESP_FIFO_SIZE;
 		u8 *src = (u8 *)addr;
 
-		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
+		esp_write8(ESP_CMD_FLUSH, ESP_CMD);
 
 		if (n > esp_count)
 			n = esp_count;
@@ -2894,7 +2894,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
 			src += n;
 			esp_count -= n;
 
-			scsi_esp_cmd(esp, ESP_CMD_TI);
+			esp_write8(ESP_CMD_TI, ESP_CMD);
 		}
 	}
 
-- 
2.16.4

[PATCH 0/6] mac_esp, zorro_esp, esp_scsi: Various improvements

[Finn Thain]

This series has fixes and cleanup for mac_esp, zorro_esp and the
core esp_scsi driver.

The improvements include elimination of duplicated code temporarily
introduced for zorro_esp.

Michael, would you please regression test this series on elgar,
if convenient? So far, only mac_esp has been tested with this code.


Finn Thain (6):
  zorro_esp: Limit DMA transfers to 65535 bytes
  esp_scsi: Track residual for PIO transfers
  esp_scsi: Grant disconnect privilege for untagged commands
  esp_scsi: Eliminate ESP_FLAG_DOING_SLOWCMD
  esp_scsi: De-duplicate PIO routines
  esp_scsi: Optimize PIO loops

 drivers/scsi/esp_scsi.c  | 192 +++++++++++++++++++++++++++++--------
 drivers/scsi/esp_scsi.h  |  10 +-
 drivers/scsi/mac_esp.c   | 171 ++-------------------------------
 drivers/scsi/zorro_esp.c | 240 +++++++----------------------------------------
 4 files changed, 201 insertions(+), 412 deletions(-)

-- 
2.16.4

Re: [PATCH 6/6] esp_scsi: Optimize PIO loops

[Michael Schmitz]

Hi Finn,

Am 13.10.2018 um 13:51 schrieb Finn Thain:
> Avoid function calls in the inner PIO loops. On a Centris 660av this
> improves throughput for sequential read transfers by about 40% and
> sequential write by about 10%.
>
> Unfortunately it is not possible to have method calls like esp_write8()
> placed inline so this is always going to be slow (even with LTO).
>
> Tested-by: Stan Johnson <userm57@yahoo.com>
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> ---
>  drivers/scsi/esp_scsi.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
> index 646701fc22a4..9f0e68cd0e99 100644
> --- a/drivers/scsi/esp_scsi.c
> +++ b/drivers/scsi/esp_scsi.c
> @@ -2788,7 +2788,7 @@ static inline unsigned int esp_wait_for_fifo(struct esp *esp)
>  		if (fbytes)
>  			return fbytes;
>
> -		udelay(2);
> +		udelay(1);
>  	} while (--i);
>
>  	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
> @@ -2804,7 +2804,7 @@ static inline int esp_wait_for_intr(struct esp *esp)
>  		if (esp->sreg & ESP_STAT_INTR)
>  			return 0;
>
> -		udelay(2);
> +		udelay(1);
>  	} while (--i);
>
>  	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
> @@ -2831,7 +2831,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
>  			if (!esp_wait_for_fifo(esp))
>  				break;
>
> -			*dst++ = esp_read8(ESP_FDATA);
> +			*dst++ = readb(esp->fifo_reg);
>  			--esp_count;
>
>  			if (!esp_count)
> @@ -2852,15 +2852,15 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
>  			}
>
>  			if (phase == ESP_MIP)
> -				scsi_esp_cmd(esp, ESP_CMD_MOK);
> +				esp_write8(ESP_CMD_MOK, ESP_CMD);

You're no longer logging this command with this patch. (That'll be the 
reason for the speedup you saw ...)

>
> -			scsi_esp_cmd(esp, ESP_CMD_TI);
> +			esp_write8(ESP_CMD_TI, ESP_CMD);

Same here..

>  		}
>  	} else {
>  		unsigned int n = ESP_FIFO_SIZE;
>  		u8 *src = (u8 *)addr;
>
> -		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
> +		esp_write8(ESP_CMD_FLUSH, ESP_CMD);

here..

>
>  		if (n > esp_count)
>  			n = esp_count;
> @@ -2894,7 +2894,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
>  			src += n;
>  			esp_count -= n;
>
> -			scsi_esp_cmd(esp, ESP_CMD_TI);
> +			esp_write8(ESP_CMD_TI, ESP_CMD);

and here.

The burst of ESP_CMD_TI's in the log was quite useful to spot what went 
wrong during PIO. Maybe mention in the changelog that commands during 
PIO are no longer logged? Or introduce a new ESP_EVENT_PIO and log that 
at the start of PIO?

Cheers,

	Michael



>  		}
>  	}
>
>

Re: [PATCH 6/6] esp_scsi: Optimize PIO loops

[Finn Thain]

On Sat, 13 Oct 2018, Michael Schmitz wrote:

> Hi Finn,
> 
> Am 13.10.2018 um 13:51 schrieb Finn Thain:
> > Avoid function calls in the inner PIO loops. On a Centris 660av this
> > improves throughput for sequential read transfers by about 40% and
> > sequential write by about 10%.
> > 
> > Unfortunately it is not possible to have method calls like esp_write8()
> > placed inline so this is always going to be slow (even with LTO).
> > 
> > Tested-by: Stan Johnson <userm57@yahoo.com>
> > Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> > ---
> >  drivers/scsi/esp_scsi.c | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
> > index 646701fc22a4..9f0e68cd0e99 100644
> > --- a/drivers/scsi/esp_scsi.c
> > +++ b/drivers/scsi/esp_scsi.c
> > @@ -2788,7 +2788,7 @@ static inline unsigned int esp_wait_for_fifo(struct
> > esp *esp)
> >  		if (fbytes)
> >  			return fbytes;
> > 
> > -		udelay(2);
> > +		udelay(1);
> >  	} while (--i);
> > 
> >  	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
> > @@ -2804,7 +2804,7 @@ static inline int esp_wait_for_intr(struct esp *esp)
> >  		if (esp->sreg & ESP_STAT_INTR)
> >  			return 0;
> > 
> > -		udelay(2);
> > +		udelay(1);
> >  	} while (--i);
> > 
> >  	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
> > @@ -2831,7 +2831,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32
> > esp_count,
> >  			if (!esp_wait_for_fifo(esp))
> >  				break;
> > 
> > -			*dst++ = esp_read8(ESP_FDATA);
> > +			*dst++ = readb(esp->fifo_reg);
> >  			--esp_count;
> > 
> >  			if (!esp_count)
> > @@ -2852,15 +2852,15 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32
> > esp_count,
> >  			}
> > 
> >  			if (phase == ESP_MIP)
> > -				scsi_esp_cmd(esp, ESP_CMD_MOK);
> > +				esp_write8(ESP_CMD_MOK, ESP_CMD);
> 
> You're no longer logging this command with this patch. (That'll be the reason
> for the speedup you saw ...)
> 
> > 
> > -			scsi_esp_cmd(esp, ESP_CMD_TI);
> > +			esp_write8(ESP_CMD_TI, ESP_CMD);
> 
> Same here..
> 
> >  		}
> >  	} else {
> >  		unsigned int n = ESP_FIFO_SIZE;
> >  		u8 *src = (u8 *)addr;
> > 
> > -		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
> > +		esp_write8(ESP_CMD_FLUSH, ESP_CMD);
> 
> here..
> 
> > 
> >  		if (n > esp_count)
> >  			n = esp_count;
> > @@ -2894,7 +2894,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32
> > esp_count,
> >  			src += n;
> >  			esp_count -= n;
> > 
> > -			scsi_esp_cmd(esp, ESP_CMD_TI);
> > +			esp_write8(ESP_CMD_TI, ESP_CMD);
> 
> and here.
> 

Yes, it's deliberate.

> The burst of ESP_CMD_TI's in the log was quite useful to spot what went 
> wrong during PIO.

I don't think it's as useful as you seem to think. Compare 
mac_esp_send_pdma_cmd().

> Maybe mention in the changelog that commands during PIO are no longer 
> logged? Or introduce a new ESP_EVENT_PIO and log that at the start of 
> PIO?
> 

Yes, and I did leave a scsi_esp_cmd(esp, cmd) call at the start of PIO. 

That should be sufficient, right?

-- 

> Cheers,
> 
> 	Michael
> 
> 
> 
> >  		}
> >  	}
> > 
> > 
> 

Re: [PATCH 6/6] esp_scsi: Optimize PIO loops

[Michael Schmitz]

Hi Finn,

Am 13.10.2018 um 17:09 schrieb Finn Thain:
> On Sat, 13 Oct 2018, Michael Schmitz wrote:
>
>> Hi Finn,
>>
>> Am 13.10.2018 um 13:51 schrieb Finn Thain:
>>> Avoid function calls in the inner PIO loops. On a Centris 660av this
>>> improves throughput for sequential read transfers by about 40% and
>>> sequential write by about 10%.
>>>
>>> Unfortunately it is not possible to have method calls like esp_write8()
>>> placed inline so this is always going to be slow (even with LTO).
>>>
>>> Tested-by: Stan Johnson <userm57@yahoo.com>
>>> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
>>> ---
>>>  drivers/scsi/esp_scsi.c | 14 +++++++-------
>>>  1 file changed, 7 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
>>> index 646701fc22a4..9f0e68cd0e99 100644
>>> --- a/drivers/scsi/esp_scsi.c
>>> +++ b/drivers/scsi/esp_scsi.c
>>> @@ -2788,7 +2788,7 @@ static inline unsigned int esp_wait_for_fifo(struct
>>> esp *esp)
>>>  		if (fbytes)
>>>  			return fbytes;
>>>
>>> -		udelay(2);
>>> +		udelay(1);
>>>  	} while (--i);
>>>
>>>  	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
>>> @@ -2804,7 +2804,7 @@ static inline int esp_wait_for_intr(struct esp *esp)
>>>  		if (esp->sreg & ESP_STAT_INTR)
>>>  			return 0;
>>>
>>> -		udelay(2);
>>> +		udelay(1);
>>>  	} while (--i);
>>>
>>>  	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
>>> @@ -2831,7 +2831,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32
>>> esp_count,
>>>  			if (!esp_wait_for_fifo(esp))
>>>  				break;
>>>
>>> -			*dst++ = esp_read8(ESP_FDATA);
>>> +			*dst++ = readb(esp->fifo_reg);
>>>  			--esp_count;
>>>
>>>  			if (!esp_count)
>>> @@ -2852,15 +2852,15 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32
>>> esp_count,
>>>  			}
>>>
>>>  			if (phase == ESP_MIP)
>>> -				scsi_esp_cmd(esp, ESP_CMD_MOK);
>>> +				esp_write8(ESP_CMD_MOK, ESP_CMD);
>>
>> You're no longer logging this command with this patch. (That'll be the reason
>> for the speedup you saw ...)
>>
>>>
>>> -			scsi_esp_cmd(esp, ESP_CMD_TI);
>>> +			esp_write8(ESP_CMD_TI, ESP_CMD);
>>
>> Same here..
>>
>>>  		}
>>>  	} else {
>>>  		unsigned int n = ESP_FIFO_SIZE;
>>>  		u8 *src = (u8 *)addr;
>>>
>>> -		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
>>> +		esp_write8(ESP_CMD_FLUSH, ESP_CMD);
>>
>> here..
>>
>>>
>>>  		if (n > esp_count)
>>>  			n = esp_count;
>>> @@ -2894,7 +2894,7 @@ void esp_send_pio_cmd(struct esp *esp, u32 addr, u32
>>> esp_count,
>>>  			src += n;
>>>  			esp_count -= n;
>>>
>>> -			scsi_esp_cmd(esp, ESP_CMD_TI);
>>> +			esp_write8(ESP_CMD_TI, ESP_CMD);
>>
>> and here.
>>
>
> Yes, it's deliberate.

I'm sure it was... and I wasn't objecting to that.

>> The burst of ESP_CMD_TI's in the log was quite useful to spot what went
>> wrong during PIO.
>
> I don't think it's as useful as you seem to think. Compare
> mac_esp_send_pdma_cmd().
>
>> Maybe mention in the changelog that commands during PIO are no longer
>> logged? Or introduce a new ESP_EVENT_PIO and log that at the start of
>> PIO?
>>
>
> Yes, and I did leave a scsi_esp_cmd(esp, cmd) call at the start of PIO.

Which I missed from just looking at the patch, sorry.

> That should be sufficient, right?

It would indeed. Thanks for clarifying.

Cheers,

	Michael

Re: [PATCH 5/6] esp_scsi: De-duplicate PIO routines

[Christoph Hellwig]

> +#if IS_ENABLED(CONFIG_SCSI_MAC_ESP) || IS_ENABLED(CONFIG_SCSI_ZORRO_ESP)

Please add a new CONFIG_SCSI_ESP_PIO symbol that is selected by
the mac and zorro drivers instead.

> +	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));

This should probably use dev_err (at least with my series).

Re: [PATCH 5/6] esp_scsi: De-duplicate PIO routines

[Finn Thain]

On Sat, 13 Oct 2018, Christoph Hellwig wrote:

> > +#if IS_ENABLED(CONFIG_SCSI_MAC_ESP) || IS_ENABLED(CONFIG_SCSI_ZORRO_ESP)
> 
> Please add a new CONFIG_SCSI_ESP_PIO symbol that is selected by
> the mac and zorro drivers instead.
> 

OK.

> > +	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
> 
> This should probably use dev_err (at least with my series).
> 

How about shost_printk()? That would be consistent with the rest of 
esp_scsi.c. It also means my series need not depend on yours which would 
complicate things.

-- 

Re: [PATCH 5/6] esp_scsi: De-duplicate PIO routines

[Christoph Hellwig]

On Sat, Oct 13, 2018 at 06:22:18PM +1100, Finn Thain wrote:
> > > +	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
> > 
> > This should probably use dev_err (at least with my series).
> > 
> 
> How about shost_printk()? That would be consistent with the rest of 
> esp_scsi.c. It also means my series need not depend on yours which would 
> complicate things.

Yes, that sounds even better.

Re: [PATCH 0/6] mac_esp, zorro_esp, esp_scsi: Various improvements

[Michael Schmitz]

Hi Finn,

Am 13.10.2018 um 13:51 schrieb Finn Thain:
> This series has fixes and cleanup for mac_esp, zorro_esp and the
> core esp_scsi driver.
>
> The improvements include elimination of duplicated code temporarily
> introduced for zorro_esp.
>
> Michael, would you please regression test this series on elgar,
> if convenient? So far, only mac_esp has been tested with this code.
>
>
> Finn Thain (6):
>   zorro_esp: Limit DMA transfers to 65535 bytes
>   esp_scsi: Track residual for PIO transfers
>   esp_scsi: Grant disconnect privilege for untagged commands
>   esp_scsi: Eliminate ESP_FLAG_DOING_SLOWCMD
>   esp_scsi: De-duplicate PIO routines
>   esp_scsi: Optimize PIO loops
>
>  drivers/scsi/esp_scsi.c  | 192 +++++++++++++++++++++++++++++--------
>  drivers/scsi/esp_scsi.h  |  10 +-
>  drivers/scsi/mac_esp.c   | 171 ++-------------------------------
>  drivers/scsi/zorro_esp.c | 240 +++++++----------------------------------------
>  4 files changed, 201 insertions(+), 412 deletions(-)
>

For Amiga zorro-esp:

Tested-by: Michael Schmitz <schmitzmic@gmail.com>

Re: [PATCH 5/6] esp_scsi: De-duplicate PIO routines

[Hannes Reinecke]

On 10/13/18 2:51 AM, Finn Thain wrote:
> As a temporary measure, the code to implement PIO transfers was
> duplicated in zorro_esp and mac_esp. Now that this code has stabilized,
> move it into the core driver to eliminate the duplication.
> 
> This replaces the inline assembler with more portable writesb() calls.
> Optimizing the m68k writesb() implementation is a separate patch.
> 
> Tested-by: Stan Johnson <userm57@yahoo.com>
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> ---
>   drivers/scsi/esp_scsi.c  | 126 +++++++++++++++++++++++++
>   drivers/scsi/esp_scsi.h  |   5 +
>   drivers/scsi/mac_esp.c   | 173 ++---------------------------------
>   drivers/scsi/zorro_esp.c | 232 +++++++----------------------------------------
>   4 files changed, 171 insertions(+), 365 deletions(-)
> 
> diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
> index 6ccaf818357e..646701fc22a4 100644
> --- a/drivers/scsi/esp_scsi.c
> +++ b/drivers/scsi/esp_scsi.c
> @@ -2776,3 +2776,129 @@ MODULE_PARM_DESC(esp_debug,
>   
>   module_init(esp_init);
>   module_exit(esp_exit);
> +
> +#if IS_ENABLED(CONFIG_SCSI_MAC_ESP) || IS_ENABLED(CONFIG_SCSI_ZORRO_ESP)
> +static inline unsigned int esp_wait_for_fifo(struct esp *esp)
> +{
> +	int i = 500000;
> +
> +	do {
> +		unsigned int fbytes = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;
> +
> +		if (fbytes)
> +			return fbytes;
> +
> +		udelay(2);
> +	} while (--i);
> +
> +	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
> +	return 0;
> +}
> +
> +static inline int esp_wait_for_intr(struct esp *esp)
> +{
> +	int i = 500000;
> +
> +	do {
> +		esp->sreg = esp_read8(ESP_STATUS);
> +		if (esp->sreg & ESP_STAT_INTR)
> +			return 0;
> +
> +		udelay(2);
> +	} while (--i);
> +
> +	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
> +	return 1;
> +}
> +
> +#define ESP_FIFO_SIZE 16
> +
> +void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
> +		      u32 dma_count, int write, u8 cmd)
> +{
> +	u8 phase = esp->sreg & ESP_STAT_PMASK;
> +
> +	cmd &= ~ESP_CMD_DMA;
> +	esp->send_cmd_error = 0;
> +
> +	if (write) {
> +		u8 *dst = (u8 *)addr;
> +		u8 mask = ~(phase == ESP_MIP ? ESP_INTR_FDONE : ESP_INTR_BSERV);
> +
> +		scsi_esp_cmd(esp, cmd);
> +
> +		while (1) {
> +			if (!esp_wait_for_fifo(esp))
> +				break;
> +
> +			*dst++ = esp_read8(ESP_FDATA);
> +			--esp_count;
> +
> +			if (!esp_count)
> +				break;
> +
> +			if (esp_wait_for_intr(esp)) {
> +				esp->send_cmd_error = 1;
> +				break;
> +			}
> +
> +			if ((esp->sreg & ESP_STAT_PMASK) != phase)
> +				break;
> +
> +			esp->ireg = esp_read8(ESP_INTRPT);
> +			if (esp->ireg & mask) {
> +				esp->send_cmd_error = 1;
> +				break;
> +			}
> +
> +			if (phase == ESP_MIP)
> +				scsi_esp_cmd(esp, ESP_CMD_MOK);
> +
> +			scsi_esp_cmd(esp, ESP_CMD_TI);
> +		}
> +	} else {
> +		unsigned int n = ESP_FIFO_SIZE;
> +		u8 *src = (u8 *)addr;
> +
> +		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
> +
> +		if (n > esp_count)
> +			n = esp_count;
> +		writesb(esp->fifo_reg, src, n);
> +		src += n;
> +		esp_count -= n;
> +
> +		scsi_esp_cmd(esp, cmd);
> +
> +		while (esp_count) {
> +			if (esp_wait_for_intr(esp)) {
> +				esp->send_cmd_error = 1;
> +				break;
> +			}
> +
> +			if ((esp->sreg & ESP_STAT_PMASK) != phase)
> +				break;
> +
> +			esp->ireg = esp_read8(ESP_INTRPT);
> +			if (esp->ireg & ~ESP_INTR_BSERV) {
> +				esp->send_cmd_error = 1;
> +				break;
> +			}
> +
> +			n = ESP_FIFO_SIZE -
> +			    (esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES);
> +
> +			if (n > esp_count)
> +				n = esp_count;
> +			writesb(esp->fifo_reg, src, n);
> +			src += n;
> +			esp_count -= n;
> +
> +			scsi_esp_cmd(esp, ESP_CMD_TI);
> +		}
> +	}
> +
> +	esp->send_cmd_residual = esp_count;
> +}
> +EXPORT_SYMBOL(esp_send_pio_cmd);
> +#endif

These function are conditional, but

> diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
> index d0c032803749..2590e5eda595 100644
> --- a/drivers/scsi/esp_scsi.h
> +++ b/drivers/scsi/esp_scsi.h
> @@ -431,6 +431,7 @@ struct esp_driver_ops {
>   struct esp {
>   	void __iomem		*regs;
>   	void __iomem		*dma_regs;
> +	u8 __iomem		*fifo_reg;
>   
>   	const struct esp_driver_ops *ops;
>   
> @@ -540,6 +541,7 @@ struct esp {
>   	void			*dma;
>   	int			dmarev;
>   
> +	int			send_cmd_error;
>   	int			send_cmd_residual;
>   };
>   
> @@ -581,4 +583,7 @@ extern void scsi_esp_unregister(struct esp *);
>   extern irqreturn_t scsi_esp_intr(int, void *);
>   extern void scsi_esp_cmd(struct esp *, u8);
>   
> +extern void esp_send_pio_cmd(struct esp *esp, u32 dma_addr, u32 esp_count,
> +			     u32 dma_count, int write, u8 cmd);
> +
>   #endif /* !(_ESP_SCSI_H) */
These are not.

Which will result in building errors when the said configuration is not 
enabled.
Please fix by either making everything conditional or remove the 
conditional completely.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

Re: [PATCH 5/6] esp_scsi: De-duplicate PIO routines

[Finn Thain]

On Mon, 15 Oct 2018, Hannes Reinecke wrote:

> On 10/13/18 2:51 AM, Finn Thain wrote:
> > As a temporary measure, the code to implement PIO transfers was
> > duplicated in zorro_esp and mac_esp. Now that this code has stabilized,
> > move it into the core driver to eliminate the duplication.
> > 
> > This replaces the inline assembler with more portable writesb() calls.
> > Optimizing the m68k writesb() implementation is a separate patch.
> > 
> > Tested-by: Stan Johnson <userm57@yahoo.com>
> > Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> > ---
> >   drivers/scsi/esp_scsi.c  | 126 +++++++++++++++++++++++++
> >   drivers/scsi/esp_scsi.h  |   5 +
> >   drivers/scsi/mac_esp.c   | 173 ++---------------------------------
> >   drivers/scsi/zorro_esp.c | 232 +++++++----------------------------------------
> >   4 files changed, 171 insertions(+), 365 deletions(-)
> > 
> > diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
> > index 6ccaf818357e..646701fc22a4 100644
> > --- a/drivers/scsi/esp_scsi.c
> > +++ b/drivers/scsi/esp_scsi.c
> > @@ -2776,3 +2776,129 @@ MODULE_PARM_DESC(esp_debug,
> >   
> >   module_init(esp_init);
> >   module_exit(esp_exit);
> > +
> > +#if IS_ENABLED(CONFIG_SCSI_MAC_ESP) || IS_ENABLED(CONFIG_SCSI_ZORRO_ESP)
> > +static inline unsigned int esp_wait_for_fifo(struct esp *esp)
> > +{
> > +	int i = 500000;
> > +
> > +	do {
> > +		unsigned int fbytes = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;
> > +
> > +		if (fbytes)
> > +			return fbytes;
> > +
> > +		udelay(2);
> > +	} while (--i);
> > +
> > +	pr_err("FIFO is empty (sreg %02x)\n", esp_read8(ESP_STATUS));
> > +	return 0;
> > +}
> > +
> > +static inline int esp_wait_for_intr(struct esp *esp)
> > +{
> > +	int i = 500000;
> > +
> > +	do {
> > +		esp->sreg = esp_read8(ESP_STATUS);
> > +		if (esp->sreg & ESP_STAT_INTR)
> > +			return 0;
> > +
> > +		udelay(2);
> > +	} while (--i);
> > +
> > +	pr_err("IRQ timeout (sreg %02x)\n", esp->sreg);
> > +	return 1;
> > +}
> > +
> > +#define ESP_FIFO_SIZE 16
> > +
> > +void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
> > +		      u32 dma_count, int write, u8 cmd)
> > +{
> > +	u8 phase = esp->sreg & ESP_STAT_PMASK;
> > +
> > +	cmd &= ~ESP_CMD_DMA;
> > +	esp->send_cmd_error = 0;
> > +
> > +	if (write) {
> > +		u8 *dst = (u8 *)addr;
> > +		u8 mask = ~(phase == ESP_MIP ? ESP_INTR_FDONE : ESP_INTR_BSERV);
> > +
> > +		scsi_esp_cmd(esp, cmd);
> > +
> > +		while (1) {
> > +			if (!esp_wait_for_fifo(esp))
> > +				break;
> > +
> > +			*dst++ = esp_read8(ESP_FDATA);
> > +			--esp_count;
> > +
> > +			if (!esp_count)
> > +				break;
> > +
> > +			if (esp_wait_for_intr(esp)) {
> > +				esp->send_cmd_error = 1;
> > +				break;
> > +			}
> > +
> > +			if ((esp->sreg & ESP_STAT_PMASK) != phase)
> > +				break;
> > +
> > +			esp->ireg = esp_read8(ESP_INTRPT);
> > +			if (esp->ireg & mask) {
> > +				esp->send_cmd_error = 1;
> > +				break;
> > +			}
> > +
> > +			if (phase == ESP_MIP)
> > +				scsi_esp_cmd(esp, ESP_CMD_MOK);
> > +
> > +			scsi_esp_cmd(esp, ESP_CMD_TI);
> > +		}
> > +	} else {
> > +		unsigned int n = ESP_FIFO_SIZE;
> > +		u8 *src = (u8 *)addr;
> > +
> > +		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
> > +
> > +		if (n > esp_count)
> > +			n = esp_count;
> > +		writesb(esp->fifo_reg, src, n);
> > +		src += n;
> > +		esp_count -= n;
> > +
> > +		scsi_esp_cmd(esp, cmd);
> > +
> > +		while (esp_count) {
> > +			if (esp_wait_for_intr(esp)) {
> > +				esp->send_cmd_error = 1;
> > +				break;
> > +			}
> > +
> > +			if ((esp->sreg & ESP_STAT_PMASK) != phase)
> > +				break;
> > +
> > +			esp->ireg = esp_read8(ESP_INTRPT);
> > +			if (esp->ireg & ~ESP_INTR_BSERV) {
> > +				esp->send_cmd_error = 1;
> > +				break;
> > +			}
> > +
> > +			n = ESP_FIFO_SIZE -
> > +			    (esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES);
> > +
> > +			if (n > esp_count)
> > +				n = esp_count;
> > +			writesb(esp->fifo_reg, src, n);
> > +			src += n;
> > +			esp_count -= n;
> > +
> > +			scsi_esp_cmd(esp, ESP_CMD_TI);
> > +		}
> > +	}
> > +
> > +	esp->send_cmd_residual = esp_count;
> > +}
> > +EXPORT_SYMBOL(esp_send_pio_cmd);
> > +#endif
> 
> These function are conditional, but
> 
> > diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
> > index d0c032803749..2590e5eda595 100644
> > --- a/drivers/scsi/esp_scsi.h
> > +++ b/drivers/scsi/esp_scsi.h
> > @@ -431,6 +431,7 @@ struct esp_driver_ops {
> >   struct esp {
> >   	void __iomem		*regs;
> >   	void __iomem		*dma_regs;
> > +	u8 __iomem		*fifo_reg;
> >   
> >   	const struct esp_driver_ops *ops;
> >   
> > @@ -540,6 +541,7 @@ struct esp {
> >   	void			*dma;
> >   	int			dmarev;
> >   
> > +	int			send_cmd_error;
> >   	int			send_cmd_residual;
> >   };
> >   
> > @@ -581,4 +583,7 @@ extern void scsi_esp_unregister(struct esp *);
> >   extern irqreturn_t scsi_esp_intr(int, void *);
> >   extern void scsi_esp_cmd(struct esp *, u8);
> >   
> > +extern void esp_send_pio_cmd(struct esp *esp, u32 dma_addr, u32 esp_count,
> > +			     u32 dma_count, int write, u8 cmd);
> > +
> >   #endif /* !(_ESP_SCSI_H) */
> These are not.
> 
> Which will result in building errors when the said configuration is not 
> enabled.

I didn't see errors or new warnings when build-testing with 
CONFIG_SCSI_AM53C974=y with gcc-5.4 or gcc-7.3, nor when build-testing 
CONFIG_SUN3X_ESP=y with gcc-4.4.

Are you perhaps thinking of "declared static but never defined"? That 
doesn't apply here because esp_send_pio_cmd() isn't static. Likewise 
"static declaration of 'foo' follows non-static declaration"...

-- 

> Cheers,
> 
> Hannes
> -- 
> Dr. Hannes Reinecke		   Teamlead Storage & Networking
> hare@suse.de			               +49 911 74053 688
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg
> GF: F. Imend?rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
> HRB 21284 (AG N?rnberg)
>