[PATCH v2 1/7] Revert "scsi: ncr5380: Increase register polling limit"

[PATCH v2 1/7] Revert "scsi: ncr5380: Increase register polling limit"

[Finn Thain]

This reverts commit 4822827a69d7cd3bc5a07b7637484ebd2cf88db6.

The purpose of that commit was to suppress a timeout warning message
which appeared to be caused by target latency. But suppressing the warning
is undesirable as the warning may indicate a messed up transfer count.

Another problem with that commit is that 15 ms is too long to keep
interrupts disabled as interrupt latency can cause system clock drift
and other problems.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 4822827a69d7 ("scsi: ncr5380: Increase register polling limit")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/NCR5380.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
index efca509b92b0..5935fd6d1a05 100644
--- a/drivers/scsi/NCR5380.h
+++ b/drivers/scsi/NCR5380.h
@@ -235,7 +235,7 @@ struct NCR5380_cmd {
 #define NCR5380_PIO_CHUNK_SIZE		256
 
 /* Time limit (ms) to poll registers when IRQs are disabled, e.g. during PDMA */
-#define NCR5380_REG_POLL_TIME		15
+#define NCR5380_REG_POLL_TIME		10
 
 static inline struct scsi_cmnd *NCR5380_to_scmd(struct NCR5380_cmd *ncmd_ptr)
 {
-- 
2.21.0

[PATCH v2 3/7] scsi: NCR5380: Handle PDMA failure reliably

[Finn Thain]

A PDMA error is handled in the core driver by setting the device's
'borken' flag and aborting the command. Unfortunately, do_abort() is not
dependable. Perform a SCSI bus reset instead, to make sure that the
command fails and gets retried.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: stable@vger.kernel.org # v4.20+
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/NCR5380.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index 08e3ea8159b3..d9fa9cf2fd8b 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -1761,10 +1761,8 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 						scmd_printk(KERN_INFO, cmd,
 							"switching to slow handshake\n");
 						cmd->device->borken = 1;
-						sink = 1;
-						do_abort(instance);
-						cmd->result = DID_ERROR << 16;
-						/* XXX - need to source or sink data here, as appropriate */
+						do_reset(instance);
+						bus_reset_cleanup(instance);
 					}
 				} else {
 					/* Transfer a small chunk so that the
-- 
2.21.0

[PATCH v2 5/7] scsi: mac_scsi: Fix pseudo DMA implementation, take 2

[Finn Thain]

A system bus error during a PDMA transfer can mess up the calculation of
the transfer residual (the PDMA handshaking hardware lacks a byte
counter). This results in data corruption.

The algorithm in this patch anticipates a bus error by starting each
transfer with a MOVE.B instruction. If a bus error is caught the transfer
will be retried. If a bus error is caught later in the transfer (for a
MOVE.W instruction) the transfer gets failed and subsequent requests for
that target will use PIO instead of PDMA.

This avoids the "!REQ and !ACK" error so the severity level of that
message is reduced to KERN_DEBUG.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@vger.kernel.org # v4.14+
Fixes: 3a0f64bfa907 ("mac_scsi: Fix pseudo DMA implementation")
Reported-by: Chris Jones <chris@martin-jones.com>
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
Changed since v1:
 - Dropped new mac_pdma.h file.
---
 drivers/scsi/mac_scsi.c | 371 +++++++++++++++++++++++-----------------
 1 file changed, 218 insertions(+), 153 deletions(-)

diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index ba1afcaadae8..27364b71e833 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -3,6 +3,8 @@
  *
  * Copyright 1998, Michael Schmitz <mschmitz@lbl.gov>
  *
+ * Copyright 2019 Finn Thain
+ *
  * derived in part from:
  */
 /*
@@ -11,6 +13,7 @@
  * Copyright 1995, Russell King
  */
 
+#include <linux/delay.h>
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/ioport.h>
@@ -89,101 +92,217 @@ static int __init mac_scsi_setup(char *str)
 __setup("mac5380=", mac_scsi_setup);
 #endif /* !MODULE */
 
-/* Pseudo DMA asm originally by Ove Edlund */
-
-#define CP_IO_TO_MEM(s,d,n)				\
-__asm__ __volatile__					\
-    ("    cmp.w  #4,%2\n"				\
-     "    bls    8f\n"					\
-     "    move.w %1,%%d0\n"				\
-     "    neg.b  %%d0\n"				\
-     "    and.w  #3,%%d0\n"				\
-     "    sub.w  %%d0,%2\n"				\
-     "    bra    2f\n"					\
-     " 1: move.b (%0),(%1)+\n"				\
-     " 2: dbf    %%d0,1b\n"				\
-     "    move.w %2,%%d0\n"				\
-     "    lsr.w  #5,%%d0\n"				\
-     "    bra    4f\n"					\
-     " 3: move.l (%0),(%1)+\n"				\
-     "31: move.l (%0),(%1)+\n"				\
-     "32: move.l (%0),(%1)+\n"				\
-     "33: move.l (%0),(%1)+\n"				\
-     "34: move.l (%0),(%1)+\n"				\
-     "35: move.l (%0),(%1)+\n"				\
-     "36: move.l (%0),(%1)+\n"				\
-     "37: move.l (%0),(%1)+\n"				\
-     " 4: dbf    %%d0,3b\n"				\
-     "    move.w %2,%%d0\n"				\
-     "    lsr.w  #2,%%d0\n"				\
-     "    and.w  #7,%%d0\n"				\
-     "    bra    6f\n"					\
-     " 5: move.l (%0),(%1)+\n"				\
-     " 6: dbf    %%d0,5b\n"				\
-     "    and.w  #3,%2\n"				\
-     "    bra    8f\n"					\
-     " 7: move.b (%0),(%1)+\n"				\
-     " 8: dbf    %2,7b\n"				\
-     "    moveq.l #0, %2\n"				\
-     " 9: \n"						\
-     ".section .fixup,\"ax\"\n"				\
-     "    .even\n"					\
-     "91: moveq.l #1, %2\n"				\
-     "    jra 9b\n"					\
-     "94: moveq.l #4, %2\n"				\
-     "    jra 9b\n"					\
-     ".previous\n"					\
-     ".section __ex_table,\"a\"\n"			\
-     "   .align 4\n"					\
-     "   .long  1b,91b\n"				\
-     "   .long  3b,94b\n"				\
-     "   .long 31b,94b\n"				\
-     "   .long 32b,94b\n"				\
-     "   .long 33b,94b\n"				\
-     "   .long 34b,94b\n"				\
-     "   .long 35b,94b\n"				\
-     "   .long 36b,94b\n"				\
-     "   .long 37b,94b\n"				\
-     "   .long  5b,94b\n"				\
-     "   .long  7b,91b\n"				\
-     ".previous"					\
-     : "=a"(s), "=a"(d), "=d"(n)			\
-     : "0"(s), "1"(d), "2"(n)				\
-     : "d0")
+/*
+ * According to "Inside Macintosh: Devices", Mac OS requires disk drivers to
+ * specify the number of bytes between the delays expected from a SCSI target.
+ * This allows the operating system to "prevent bus errors when a target fails
+ * to deliver the next byte within the processor bus error timeout period."
+ * Linux SCSI drivers lack knowledge of the timing behaviour of SCSI targets
+ * so bus errors are unavoidable.
+ *
+ * If a MOVE.B instruction faults, we assume that zero bytes were transferred
+ * and simply retry. That assumption probably depends on target behaviour but
+ * seems to hold up okay. The NOP provides synchronization: without it the
+ * fault can sometimes occur after the program counter has moved past the
+ * offending instruction. Post-increment addressing can't be used.
+ */
+
+#define MOVE_BYTE(operands) \
+	asm volatile ( \
+		"1:     moveb " operands "     \n" \
+		"11:    nop                    \n" \
+		"       addq #1,%0             \n" \
+		"       subq #1,%1             \n" \
+		"40:                           \n" \
+		"                              \n" \
+		".section .fixup,\"ax\"        \n" \
+		".even                         \n" \
+		"90:    movel #1, %2           \n" \
+		"       jra 40b                \n" \
+		".previous                     \n" \
+		"                              \n" \
+		".section __ex_table,\"a\"     \n" \
+		".align  4                     \n" \
+		".long   1b,90b                \n" \
+		".long  11b,90b                \n" \
+		".previous                     \n" \
+		: "+a" (addr), "+r" (n), "+r" (result) : "a" (io))
+
+/*
+ * If a MOVE.W (or MOVE.L) instruction faults, it cannot be retried because
+ * the residual byte count would be uncertain. In that situation the MOVE_WORD
+ * macro clears n in the fixup section to abort the transfer.
+ */
+
+#define MOVE_WORD(operands) \
+	asm volatile ( \
+		"1:     movew " operands "     \n" \
+		"11:    nop                    \n" \
+		"       subq #2,%1             \n" \
+		"40:                           \n" \
+		"                              \n" \
+		".section .fixup,\"ax\"        \n" \
+		".even                         \n" \
+		"90:    movel #0, %1           \n" \
+		"       movel #2, %2           \n" \
+		"       jra 40b                \n" \
+		".previous                     \n" \
+		"                              \n" \
+		".section __ex_table,\"a\"     \n" \
+		".align  4                     \n" \
+		".long   1b,90b                \n" \
+		".long  11b,90b                \n" \
+		".previous                     \n" \
+		: "+a" (addr), "+r" (n), "+r" (result) : "a" (io))
+
+#define MOVE_16_WORDS(operands) \
+	asm volatile ( \
+		"1:     movew " operands "     \n" \
+		"2:     movew " operands "     \n" \
+		"3:     movew " operands "     \n" \
+		"4:     movew " operands "     \n" \
+		"5:     movew " operands "     \n" \
+		"6:     movew " operands "     \n" \
+		"7:     movew " operands "     \n" \
+		"8:     movew " operands "     \n" \
+		"9:     movew " operands "     \n" \
+		"10:    movew " operands "     \n" \
+		"11:    movew " operands "     \n" \
+		"12:    movew " operands "     \n" \
+		"13:    movew " operands "     \n" \
+		"14:    movew " operands "     \n" \
+		"15:    movew " operands "     \n" \
+		"16:    movew " operands "     \n" \
+		"17:    nop                    \n" \
+		"       subl  #32,%1           \n" \
+		"40:                           \n" \
+		"                              \n" \
+		".section .fixup,\"ax\"        \n" \
+		".even                         \n" \
+		"90:    movel #0, %1           \n" \
+		"       movel #2, %2           \n" \
+		"       jra 40b                \n" \
+		".previous                     \n" \
+		"                              \n" \
+		".section __ex_table,\"a\"     \n" \
+		".align  4                     \n" \
+		".long   1b,90b                \n" \
+		".long   2b,90b                \n" \
+		".long   3b,90b                \n" \
+		".long   4b,90b                \n" \
+		".long   5b,90b                \n" \
+		".long   6b,90b                \n" \
+		".long   7b,90b                \n" \
+		".long   8b,90b                \n" \
+		".long   9b,90b                \n" \
+		".long  10b,90b                \n" \
+		".long  11b,90b                \n" \
+		".long  12b,90b                \n" \
+		".long  13b,90b                \n" \
+		".long  14b,90b                \n" \
+		".long  15b,90b                \n" \
+		".long  16b,90b                \n" \
+		".long  17b,90b                \n" \
+		".previous                     \n" \
+		: "+a" (addr), "+r" (n), "+r" (result) : "a" (io))
+
+#define MAC_PDMA_DELAY		32
+
+static inline int mac_pdma_recv(void __iomem *io, unsigned char *start, int n)
+{
+	unsigned char *addr = start;
+	int result = 0;
+
+	if (n >= 1) {
+		MOVE_BYTE("%3@,%0@");
+		if (result)
+			goto out;
+	}
+	if (n >= 1 && ((unsigned long)addr & 1)) {
+		MOVE_BYTE("%3@,%0@");
+		if (result)
+			goto out;
+	}
+	while (n >= 32)
+		MOVE_16_WORDS("%3@,%0@+");
+	while (n >= 2)
+		MOVE_WORD("%3@,%0@+");
+	if (result)
+		return start - addr; /* Negated to indicate uncertain length */
+	if (n == 1)
+		MOVE_BYTE("%3@,%0@");
+out:
+	return addr - start;
+}
+
+static inline int mac_pdma_send(unsigned char *start, void __iomem *io, int n)
+{
+	unsigned char *addr = start;
+	int result = 0;
+
+	if (n >= 1) {
+		MOVE_BYTE("%0@,%3@");
+		if (result)
+			goto out;
+	}
+	if (n >= 1 && ((unsigned long)addr & 1)) {
+		MOVE_BYTE("%0@,%3@");
+		if (result)
+			goto out;
+	}
+	while (n >= 32)
+		MOVE_16_WORDS("%0@+,%3@");
+	while (n >= 2)
+		MOVE_WORD("%0@+,%3@");
+	if (result)
+		return start - addr; /* Negated to indicate uncertain length */
+	if (n == 1)
+		MOVE_BYTE("%0@,%3@");
+out:
+	return addr - start;
+}
 
 static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
                                 unsigned char *dst, int len)
 {
 	u8 __iomem *s = hostdata->pdma_io + (INPUT_DATA_REG << 4);
 	unsigned char *d = dst;
-	int n = len;
-	int transferred;
+
+	hostdata->pdma_residual = len;
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
 	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
-		CP_IO_TO_MEM(s, d, n);
+		int bytes;
 
-		transferred = d - dst - n;
-		hostdata->pdma_residual = len - transferred;
+		bytes = mac_pdma_recv(s, d, min(hostdata->pdma_residual, 512));
 
-		/* No bus error. */
-		if (n == 0)
+		if (bytes > 0) {
+			d += bytes;
+			hostdata->pdma_residual -= bytes;
+		}
+
+		if (hostdata->pdma_residual == 0)
 			return 0;
 
-		/* Target changed phase early? */
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
-		                           BUS_AND_STATUS_REG, BASR_ACK, BASR_ACK, HZ / 64) < 0)
-			scmd_printk(KERN_ERR, hostdata->connected,
+		                           BUS_AND_STATUS_REG, BASR_ACK,
+		                           BASR_ACK, HZ / 64) < 0)
+			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
 			return 0;
 
+		if (bytes == 0)
+			udelay(MAC_PDMA_DELAY);
+
+		if (bytes >= 0)
+			continue;
+
 		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
-		         "%s: bus error (%d/%d)\n", __func__, transferred, len);
+		         "%s: bus error (%d/%d)\n", __func__, d - dst, len);
 		NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
-		d = dst + transferred;
-		n = len - transferred;
+		return -1;
 	}
 
 	scmd_printk(KERN_ERR, hostdata->connected,
@@ -192,93 +311,27 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 	return -1;
 }
 
-
-#define CP_MEM_TO_IO(s,d,n)				\
-__asm__ __volatile__					\
-    ("    cmp.w  #4,%2\n"				\
-     "    bls    8f\n"					\
-     "    move.w %0,%%d0\n"				\
-     "    neg.b  %%d0\n"				\
-     "    and.w  #3,%%d0\n"				\
-     "    sub.w  %%d0,%2\n"				\
-     "    bra    2f\n"					\
-     " 1: move.b (%0)+,(%1)\n"				\
-     " 2: dbf    %%d0,1b\n"				\
-     "    move.w %2,%%d0\n"				\
-     "    lsr.w  #5,%%d0\n"				\
-     "    bra    4f\n"					\
-     " 3: move.l (%0)+,(%1)\n"				\
-     "31: move.l (%0)+,(%1)\n"				\
-     "32: move.l (%0)+,(%1)\n"				\
-     "33: move.l (%0)+,(%1)\n"				\
-     "34: move.l (%0)+,(%1)\n"				\
-     "35: move.l (%0)+,(%1)\n"				\
-     "36: move.l (%0)+,(%1)\n"				\
-     "37: move.l (%0)+,(%1)\n"				\
-     " 4: dbf    %%d0,3b\n"				\
-     "    move.w %2,%%d0\n"				\
-     "    lsr.w  #2,%%d0\n"				\
-     "    and.w  #7,%%d0\n"				\
-     "    bra    6f\n"					\
-     " 5: move.l (%0)+,(%1)\n"				\
-     " 6: dbf    %%d0,5b\n"				\
-     "    and.w  #3,%2\n"				\
-     "    bra    8f\n"					\
-     " 7: move.b (%0)+,(%1)\n"				\
-     " 8: dbf    %2,7b\n"				\
-     "    moveq.l #0, %2\n"				\
-     " 9: \n"						\
-     ".section .fixup,\"ax\"\n"				\
-     "    .even\n"					\
-     "91: moveq.l #1, %2\n"				\
-     "    jra 9b\n"					\
-     "94: moveq.l #4, %2\n"				\
-     "    jra 9b\n"					\
-     ".previous\n"					\
-     ".section __ex_table,\"a\"\n"			\
-     "   .align 4\n"					\
-     "   .long  1b,91b\n"				\
-     "   .long  3b,94b\n"				\
-     "   .long 31b,94b\n"				\
-     "   .long 32b,94b\n"				\
-     "   .long 33b,94b\n"				\
-     "   .long 34b,94b\n"				\
-     "   .long 35b,94b\n"				\
-     "   .long 36b,94b\n"				\
-     "   .long 37b,94b\n"				\
-     "   .long  5b,94b\n"				\
-     "   .long  7b,91b\n"				\
-     ".previous"					\
-     : "=a"(s), "=a"(d), "=d"(n)			\
-     : "0"(s), "1"(d), "2"(n)				\
-     : "d0")
-
 static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
                                  unsigned char *src, int len)
 {
 	unsigned char *s = src;
 	u8 __iomem *d = hostdata->pdma_io + (OUTPUT_DATA_REG << 4);
-	int n = len;
-	int transferred;
+
+	hostdata->pdma_residual = len;
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
 	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
-		CP_MEM_TO_IO(s, d, n);
+		int bytes;
 
-		transferred = s - src - n;
-		hostdata->pdma_residual = len - transferred;
+		bytes = mac_pdma_send(s, d, min(hostdata->pdma_residual, 512));
 
-		/* Target changed phase early? */
-		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
-		                           BUS_AND_STATUS_REG, BASR_ACK, BASR_ACK, HZ / 64) < 0)
-			scmd_printk(KERN_ERR, hostdata->connected,
-			            "%s: !REQ and !ACK\n", __func__);
-		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
-			return 0;
+		if (bytes > 0) {
+			s += bytes;
+			hostdata->pdma_residual -= bytes;
+		}
 
-		/* No bus error. */
-		if (n == 0) {
+		if (hostdata->pdma_residual == 0) {
 			if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 			                          TCR_LAST_BYTE_SENT,
 			                          TCR_LAST_BYTE_SENT, HZ / 64) < 0)
@@ -287,17 +340,29 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 			return 0;
 		}
 
+		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
+		                           BUS_AND_STATUS_REG, BASR_ACK,
+		                           BASR_ACK, HZ / 64) < 0)
+			scmd_printk(KERN_DEBUG, hostdata->connected,
+			            "%s: !REQ and !ACK\n", __func__);
+		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
+			return 0;
+
+		if (bytes == 0)
+			udelay(MAC_PDMA_DELAY);
+
+		if (bytes >= 0)
+			continue;
+
 		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
-		         "%s: bus error (%d/%d)\n", __func__, transferred, len);
+		         "%s: bus error (%d/%d)\n", __func__, s - src, len);
 		NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
-		s = src + transferred;
-		n = len - transferred;
+		return -1;
 	}
 
 	scmd_printk(KERN_ERR, hostdata->connected,
 	            "%s: phase mismatch or !DRQ\n", __func__);
 	NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
-
 	return -1;
 }
 
-- 
2.21.0

[PATCH v2 0/7] NCR5380 drivers: fixes and other improvements

[Finn Thain]

Among other improvements, this patch series fixes a data corruption bug
in the mac_scsi driver and a bug in the EH abort routine in the core
5380 driver.

For consistency I have ignored certain checkpatch.pl complaints about
the indentation in mac_scsi.c. The remaining complaints seem to be
false positives.

Some of these patches are not trivial to backport. Those patches have
been nominated for recent -stable branches only.

Changed since v1:
 - Added acked-by tag.
 - Dropped new mac_pdma.h file.


Finn Thain (7):
  Revert "scsi: ncr5380: Increase register polling limit"
  scsi: NCR5380: Always re-enable reselection interrupt
  scsi: NCR5380: Handle PDMA failure reliably
  scsi: mac_scsi: Increase PIO/PDMA transfer length threshold
  scsi: mac_scsi: Fix pseudo DMA implementation, take 2
  scsi: mac_scsi: Enable PDMA on Mac IIfx
  scsi: mac_scsi: Treat Last Byte Sent time-out as failure

 arch/m68k/mac/config.c  |  10 +-
 drivers/scsi/NCR5380.c  |  18 +-
 drivers/scsi/NCR5380.h  |   2 +-
 drivers/scsi/mac_scsi.c | 421 +++++++++++++++++++++++++---------------
 4 files changed, 273 insertions(+), 178 deletions(-)

-- 
2.21.0

[PATCH v2 4/7] scsi: mac_scsi: Increase PIO/PDMA transfer length threshold

[Finn Thain]

Some targets introduce delays when handshaking the response to certain
commands. For example, a disk may send a 96-byte response to an INQUIRY
command (or a 24-byte response to a MODE SENSE command) too slowly.

Apparently the first 12 or 14 bytes are handshaked okay but then the
system bus error timeout is reached while transferring the next word.

Since the scsi bus phase hasn't changed, the driver then sets the target
borken flag to prevent further PDMA transfers. The driver also logs the
warning, "switching to slow handshake".

Raise the PDMA threshold to 512 bytes so that PIO transfers will be used
for these commands. This default is sufficiently low that PDMA will still
be used for READ and WRITE commands.

The existing threshold (16 bytes) was chosen more or less at random.
However, best performance requires the threshold to be as low as possible.
Those systems that don't need the PIO workaround at all may benefit from
mac_scsi.setup_use_pdma=1

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: stable@vger.kernel.org # v4.14+
Fixes: 3a0f64bfa907 ("mac_scsi: Fix pseudo DMA implementation")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/mac_scsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index 8b4b5b1a13d7..ba1afcaadae8 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -52,7 +52,7 @@ static int setup_cmd_per_lun = -1;
 module_param(setup_cmd_per_lun, int, 0);
 static int setup_sg_tablesize = -1;
 module_param(setup_sg_tablesize, int, 0);
-static int setup_use_pdma = -1;
+static int setup_use_pdma = 512;
 module_param(setup_use_pdma, int, 0);
 static int setup_hostid = -1;
 module_param(setup_hostid, int, 0);
@@ -305,7 +305,7 @@ static int macscsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,
                                 struct scsi_cmnd *cmd)
 {
 	if (hostdata->flags & FLAG_NO_PSEUDO_DMA ||
-	    cmd->SCp.this_residual < 16)
+	    cmd->SCp.this_residual < setup_use_pdma)
 		return 0;
 
 	return cmd->SCp.this_residual;
-- 
2.21.0

[PATCH v2 2/7] scsi: NCR5380: Always re-enable reselection interrupt

[Finn Thain]

The reselection interrupt gets disabled during selection and must be
re-enabled when hostdata->connected becomes NULL. If it isn't re-enabled
a disconnected command may time-out or the target may wedge the bus while
trying to reselect the host. This can happen after a command is aborted.

Fix this by enabling the reselection interrupt in NCR5380_main() after
calls to NCR5380_select() and NCR5380_information_transfer() return.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: stable@vger.kernel.org # v4.9+
Fixes: 8b00c3d5d40d ("ncr5380: Implement new eh_abort_handler")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/NCR5380.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index fe0535affc14..08e3ea8159b3 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -709,6 +709,8 @@ static void NCR5380_main(struct work_struct *work)
 			NCR5380_information_transfer(instance);
 			done = 0;
 		}
+		if (!hostdata->connected)
+			NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
 		spin_unlock_irq(&hostdata->lock);
 		if (!done)
 			cond_resched();
@@ -1110,8 +1112,6 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 		spin_lock_irq(&hostdata->lock);
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 		NCR5380_reselect(instance);
-		if (!hostdata->connected)
-			NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
 		shost_printk(KERN_ERR, instance, "reselection after won arbitration?\n");
 		goto out;
 	}
@@ -1119,7 +1119,6 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 	if (err < 0) {
 		spin_lock_irq(&hostdata->lock);
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
-		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
 
 		/* Can't touch cmd if it has been reclaimed by the scsi ML */
 		if (!hostdata->selecting)
@@ -1157,7 +1156,6 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 	if (err < 0) {
 		shost_printk(KERN_ERR, instance, "select: REQ timeout\n");
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
-		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
 		goto out;
 	}
 	if (!hostdata->selecting) {
@@ -1826,9 +1824,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 					 */
 					NCR5380_write(TARGET_COMMAND_REG, 0);
 
-					/* Enable reselect interrupts */
-					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
-
 					maybe_release_dma_irq(instance);
 					return;
 				case MESSAGE_REJECT:
@@ -1860,8 +1855,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 					 */
 					NCR5380_write(TARGET_COMMAND_REG, 0);
 
-					/* Enable reselect interrupts */
-					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
 #ifdef SUN3_SCSI_VME
 					dregs->csr |= CSR_DMA_ENABLE;
 #endif
@@ -1964,7 +1957,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 					cmd->result = DID_ERROR << 16;
 					complete_cmd(instance, cmd);
 					maybe_release_dma_irq(instance);
-					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
 					return;
 				}
 				msgout = NOP;
-- 
2.21.0

Re: [PATCH v2 5/7] scsi: mac_scsi: Fix pseudo DMA implementation, take 2

[Finn Thain]

On Mon, 10 Jun 2019, Sasha Levin wrote:

> Hi,
> 
> [This is an automated email]
> 
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: 3a0f64bfa907 mac_scsi: Fix pseudo DMA implementation.
> 
> The bot has tested the following trees: v5.1.7, v4.19.48, v4.14.123, v4.9.180.
> 
> v5.1.7: Build OK!
> v4.19.48: Build OK!
> v4.14.123: Build OK!
> v4.9.180: Failed to apply! Possible dependencies:
>     25894d1f98ae ("scsi: ncr5380: Improve hostdata struct member alignment and cache-ability")
>     4a98f896bf2c ("scsi: ncr5380: Use correct types for DMA routines")
>     61e1ce588b10 ("scsi: ncr5380: Use correct types for device register accessors")
>     820682b1b34e ("scsi: ncr5380: Store IO ports and addresses in host private data")
>     abd12b09292c ("scsi: atari_scsi: Make device register accessors re-entrant")
>     b61bacbc2bf5 ("scsi: g_NCR5380: Merge g_NCR5380 and g_NCR5380_mmio drivers")
>     d4408dd7ecff ("scsi: ncr5380: Simplify register polling limit")
>     d5d37a0ab13b ("scsi: ncr5380: Pass hostdata pointer to register polling routines")
> 
> 
> How should we proceed with this patch?
> 


Please don't backport to v4.9.y.

I added a Cc header in the hope of avoiding this question (Cc: 
stable@vger.kernel.org # v4.14+) but it appears that this bot doesn't work 
that way.

For this particular platform, v4.9.y would need quite a few patches to 
bring it up to the same level of stability and functionality as v4.14.y or 
v4.19.y. I don't really want to pursue that so I drew the line at v4.14.y.

Thanks.

-- 

> --
> Thanks,
> Sasha
> 

Re: [PATCH v2 2/7] scsi: NCR5380: Always re-enable reselection interrupt

[Finn Thain]

On Mon, 10 Jun 2019, Sasha Levin wrote:

> Hi,
> 
> [This is an automated email]
> 
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: 8b00c3d5d40d ncr5380: Implement new eh_abort_handler.
> 
> The bot has tested the following trees: v5.1.7, v4.19.48, v4.14.123, v4.9.180.
> 
> v5.1.7: Build OK!
> v4.19.48: Failed to apply! Possible dependencies:
>     6a162836997c ("scsi: NCR5380: Reduce goto statements in NCR5380_select()")
> 
> v4.14.123: Failed to apply! Possible dependencies:
>     6a162836997c ("scsi: NCR5380: Reduce goto statements in NCR5380_select()")
> 
> v4.9.180: Failed to apply! Possible dependencies:
>     6a162836997c ("scsi: NCR5380: Reduce goto statements in NCR5380_select()")
> 
> 
> How should we proceed with this patch?
> 
> --
> Thanks,
> Sasha
> 

Please cherry-pick the dependency, 6a162836997c. It does not alter any 
functionality.

-- 

Re: [PATCH v2 2/7] scsi: NCR5380: Always re-enable reselection interrupt

[Michael Schmitz]

Hi Finn,

IIRC I'd tested that change as well - didn't change broken target 
behaviour but no regressions in other respects. Add my tested-by if needed.

Cheers,

	Michael


Am 09.06.2019 um 13:19 schrieb Finn Thain:
> The reselection interrupt gets disabled during selection and must be
> re-enabled when hostdata->connected becomes NULL. If it isn't re-enabled
> a disconnected command may time-out or the target may wedge the bus while
> trying to reselect the host. This can happen after a command is aborted.
>
> Fix this by enabling the reselection interrupt in NCR5380_main() after
> calls to NCR5380_select() and NCR5380_information_transfer() return.
>
> Cc: Michael Schmitz <schmitzmic@gmail.com>
> Cc: stable@vger.kernel.org # v4.9+
> Fixes: 8b00c3d5d40d ("ncr5380: Implement new eh_abort_handler")
> Tested-by: Stan Johnson <userm57@yahoo.com>
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> ---
>  drivers/scsi/NCR5380.c | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> index fe0535affc14..08e3ea8159b3 100644
> --- a/drivers/scsi/NCR5380.c
> +++ b/drivers/scsi/NCR5380.c
> @@ -709,6 +709,8 @@ static void NCR5380_main(struct work_struct *work)
>  			NCR5380_information_transfer(instance);
>  			done = 0;
>  		}
> +		if (!hostdata->connected)
> +			NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
>  		spin_unlock_irq(&hostdata->lock);
>  		if (!done)
>  			cond_resched();
> @@ -1110,8 +1112,6 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
>  		spin_lock_irq(&hostdata->lock);
>  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
>  		NCR5380_reselect(instance);
> -		if (!hostdata->connected)
> -			NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
>  		shost_printk(KERN_ERR, instance, "reselection after won arbitration?\n");
>  		goto out;
>  	}
> @@ -1119,7 +1119,6 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
>  	if (err < 0) {
>  		spin_lock_irq(&hostdata->lock);
>  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
> -		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
>
>  		/* Can't touch cmd if it has been reclaimed by the scsi ML */
>  		if (!hostdata->selecting)
> @@ -1157,7 +1156,6 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
>  	if (err < 0) {
>  		shost_printk(KERN_ERR, instance, "select: REQ timeout\n");
>  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
> -		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
>  		goto out;
>  	}
>  	if (!hostdata->selecting) {
> @@ -1826,9 +1824,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  					 */
>  					NCR5380_write(TARGET_COMMAND_REG, 0);
>
> -					/* Enable reselect interrupts */
> -					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
> -
>  					maybe_release_dma_irq(instance);
>  					return;
>  				case MESSAGE_REJECT:
> @@ -1860,8 +1855,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  					 */
>  					NCR5380_write(TARGET_COMMAND_REG, 0);
>
> -					/* Enable reselect interrupts */
> -					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
>  #ifdef SUN3_SCSI_VME
>  					dregs->csr |= CSR_DMA_ENABLE;
>  #endif
> @@ -1964,7 +1957,6 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  					cmd->result = DID_ERROR << 16;
>  					complete_cmd(instance, cmd);
>  					maybe_release_dma_irq(instance);
> -					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
>  					return;
>  				}
>  				msgout = NOP;
>

Re: [PATCH v2 2/7] scsi: NCR5380: Always re-enable reselection interrupt

[Finn Thain]

On Tue, 11 Jun 2019, Michael Schmitz wrote:

> Hi Finn,
> 
> IIRC I'd tested that change as well - didn't change broken target 
> behaviour but no regressions in other respects. Add my tested-by if 
> needed.
> 

Unfortunately I can't confirm that this is the same patch as the one you 
tested as I no longer have that commit. But Stan did test a wide variety 
of targets and I'm confident that the reselection code path was covered.

-- 

> Cheers,
> 
> 	Michael
> 
> 
> Am 09.06.2019 um 13:19 schrieb Finn Thain:
> > The reselection interrupt gets disabled during selection and must be
> > re-enabled when hostdata->connected becomes NULL. If it isn't re-enabled
> > a disconnected command may time-out or the target may wedge the bus while
> > trying to reselect the host. This can happen after a command is aborted.
> > 
> > Fix this by enabling the reselection interrupt in NCR5380_main() after
> > calls to NCR5380_select() and NCR5380_information_transfer() return.
> > 
> > Cc: Michael Schmitz <schmitzmic@gmail.com>
> > Cc: stable@vger.kernel.org # v4.9+
> > Fixes: 8b00c3d5d40d ("ncr5380: Implement new eh_abort_handler")
> > Tested-by: Stan Johnson <userm57@yahoo.com>
> > Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> > ---
> >  drivers/scsi/NCR5380.c | 12 ++----------
> >  1 file changed, 2 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> > index fe0535affc14..08e3ea8159b3 100644
> > --- a/drivers/scsi/NCR5380.c
> > +++ b/drivers/scsi/NCR5380.c
> > @@ -709,6 +709,8 @@ static void NCR5380_main(struct work_struct *work)
> >  			NCR5380_information_transfer(instance);
> >  			done = 0;
> >  		}
> > +		if (!hostdata->connected)
> > +			NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
> >  		spin_unlock_irq(&hostdata->lock);
> >  		if (!done)
> >  			cond_resched();
> > @@ -1110,8 +1112,6 @@ static bool NCR5380_select(struct Scsi_Host *instance,
> > struct scsi_cmnd *cmd)
> >  		spin_lock_irq(&hostdata->lock);
> >  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
> >  		NCR5380_reselect(instance);
> > -		if (!hostdata->connected)
> > -			NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
> >  		shost_printk(KERN_ERR, instance, "reselection after won
> > arbitration?\n");
> >  		goto out;
> >  	}
> > @@ -1119,7 +1119,6 @@ static bool NCR5380_select(struct Scsi_Host *instance,
> > struct scsi_cmnd *cmd)
> >  	if (err < 0) {
> >  		spin_lock_irq(&hostdata->lock);
> >  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
> > -		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
> > 
> >  		/* Can't touch cmd if it has been reclaimed by the scsi ML */
> >  		if (!hostdata->selecting)
> > @@ -1157,7 +1156,6 @@ static bool NCR5380_select(struct Scsi_Host *instance,
> > struct scsi_cmnd *cmd)
> >  	if (err < 0) {
> >  		shost_printk(KERN_ERR, instance, "select: REQ timeout\n");
> >  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
> > -		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
> >  		goto out;
> >  	}
> >  	if (!hostdata->selecting) {
> > @@ -1826,9 +1824,6 @@ static void NCR5380_information_transfer(struct
> > Scsi_Host *instance)
> >  					 */
> >  					NCR5380_write(TARGET_COMMAND_REG, 0);
> > 
> > -					/* Enable reselect interrupts */
> > -					NCR5380_write(SELECT_ENABLE_REG,
> > hostdata->id_mask);
> > -
> >  					maybe_release_dma_irq(instance);
> >  					return;
> >  				case MESSAGE_REJECT:
> > @@ -1860,8 +1855,6 @@ static void NCR5380_information_transfer(struct
> > Scsi_Host *instance)
> >  					 */
> >  					NCR5380_write(TARGET_COMMAND_REG, 0);
> > 
> > -					/* Enable reselect interrupts */
> > -					NCR5380_write(SELECT_ENABLE_REG,
> > hostdata->id_mask);
> >  #ifdef SUN3_SCSI_VME
> >  					dregs->csr |= CSR_DMA_ENABLE;
> >  #endif
> > @@ -1964,7 +1957,6 @@ static void NCR5380_information_transfer(struct
> > Scsi_Host *instance)
> >  					cmd->result = DID_ERROR << 16;
> >  					complete_cmd(instance, cmd);
> >  					maybe_release_dma_irq(instance);
> > -					NCR5380_write(SELECT_ENABLE_REG,
> > hostdata->id_mask);
> >  					return;
> >  				}
> >  				msgout = NOP;
> > 
> 

Re: [PATCH v2 2/7] scsi: NCR5380: Always re-enable reselection interrupt

[Michael Schmitz]

Hi Finn,

On 11/06/19 9:33 PM, Finn Thain wrote:
> On Tue, 11 Jun 2019, Michael Schmitz wrote:
>
>> Hi Finn,
>>
>> IIRC I'd tested that change as well - didn't change broken target
>> behaviour but no regressions in other respects. Add my tested-by if
>> needed.
>>
> Unfortunately I can't confirm that this is the same patch as the one you
> tested as I no longer have that commit. But Stan did test a wide variety
> of targets and I'm confident that the reselection code path was covered.
>
No matter - patch applied cleanly to what I'm running on my Falcon, and 
works just fine for now (stresstest will take a few hours to complete). 
And that'll thoroughly exercise the reselection code path, from what 
we've seen before.

Cheers,

     Michael

Re: [PATCH v2 2/7] scsi: NCR5380: Always re-enable reselection interrupt

[Martin K. Petersen]

Michael,

> No matter - patch applied cleanly to what I'm running on my Falcon,
> and works just fine for now (stresstest will take a few hours to
> complete). And that'll thoroughly exercise the reselection code path,
> from what we've seen before.

How did it go?

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH v2 2/7] scsi: NCR5380: Always re-enable reselection interrupt

[Michael Schmitz]

Martin,

On 19/06/19 12:47 PM, Martin K. Petersen wrote:
> Michael,
>
>> No matter - patch applied cleanly to what I'm running on my Falcon,
>> and works just fine for now (stresstest will take a few hours to
>> complete). And that'll thoroughly exercise the reselection code path,
>> from what we've seen before.
> How did it go?


Just fine - repeated with different settings for can_queue and 
cmd_per_lun, with not a single hitch. No regression at all.

Cheers,

     Michael



>

Re: [PATCH v2 0/7] NCR5380 drivers: fixes and other improvements

[Martin K. Petersen]

Finn,

> Among other improvements, this patch series fixes a data corruption bug
> in the mac_scsi driver and a bug in the EH abort routine in the core
> 5380 driver.
>
> For consistency I have ignored certain checkpatch.pl complaints about
> the indentation in mac_scsi.c. The remaining complaints seem to be
> false positives.
>
> Some of these patches are not trivial to backport. Those patches have
> been nominated for recent -stable branches only.

Applied to 5.3/scsi-queue, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering