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linux/drivers/scsi/mac_scsi.c
Finn Thain 7398cee4c3 scsi: mac_scsi: Increase PIO/PDMA transfer length threshold 
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: 3a0f64bfa9 ("mac_scsi: Fix pseudo DMA implementation")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-20 15:37:03 -04:00

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/*
* Generic Macintosh NCR5380 driver
*
* Copyright 1998, Michael Schmitz <mschmitz@lbl.gov>
*
* derived in part from:
*/
/*
* Generic Generic NCR5380 driver
*
* Copyright 1995, Russell King
*/
#include <linux/types.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <asm/hwtest.h>
#include <asm/io.h>
#include <asm/macints.h>
#include <asm/setup.h>
#include <scsi/scsi_host.h>
/* Definitions for the core NCR5380 driver. */
#define NCR5380_implementation_fields int pdma_residual
#define NCR5380_read(reg) in_8(hostdata->io + ((reg) << 4))
#define NCR5380_write(reg, value) out_8(hostdata->io + ((reg) << 4), value)
#define NCR5380_dma_xfer_len macscsi_dma_xfer_len
#define NCR5380_dma_recv_setup macscsi_pread
#define NCR5380_dma_send_setup macscsi_pwrite
#define NCR5380_dma_residual macscsi_dma_residual
#define NCR5380_intr macscsi_intr
#define NCR5380_queue_command macscsi_queue_command
#define NCR5380_abort macscsi_abort
#define NCR5380_host_reset macscsi_host_reset
#define NCR5380_info macscsi_info
#include "NCR5380.h"
static int setup_can_queue = -1;
module_param(setup_can_queue, int, 0);
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 = 512;
module_param(setup_use_pdma, int, 0);
static int setup_hostid = -1;
module_param(setup_hostid, int, 0);
static int setup_toshiba_delay = -1;
module_param(setup_toshiba_delay, int, 0);
#ifndef MODULE
static int __init mac_scsi_setup(char *str)
{
int ints[8];
(void)get_options(str, ARRAY_SIZE(ints), ints);
if (ints[0] < 1) {
pr_err("Usage: mac5380=<can_queue>[,<cmd_per_lun>[,<sg_tablesize>[,<hostid>[,<use_tags>[,<use_pdma>[,<toshiba_delay>]]]]]]\n");
return 0;
}
if (ints[0] >= 1)
setup_can_queue = ints[1];
if (ints[0] >= 2)
setup_cmd_per_lun = ints[2];
if (ints[0] >= 3)
setup_sg_tablesize = ints[3];
if (ints[0] >= 4)
setup_hostid = ints[4];
/* ints[5] (use_tagged_queuing) is ignored */
if (ints[0] >= 6)
setup_use_pdma = ints[6];
if (ints[0] >= 7)
setup_toshiba_delay = ints[7];
return 1;
}
__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")
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;
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);
transferred = d - dst - n;
hostdata->pdma_residual = len - transferred;
/* No bus error. */
if (n == 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,
"%s: !REQ and !ACK\n", __func__);
if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
return 0;
dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
"%s: bus error (%d/%d)\n", __func__, transferred, len);
NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
d = dst + transferred;
n = len - transferred;
}
scmd_printk(KERN_ERR, hostdata->connected,
"%s: phase mismatch or !DRQ\n", __func__);
NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
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;
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);
transferred = s - src - n;
hostdata->pdma_residual = len - transferred;
/* 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;
/* No bus error. */
if (n == 0) {
if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
TCR_LAST_BYTE_SENT,
TCR_LAST_BYTE_SENT, HZ / 64) < 0)
scmd_printk(KERN_ERR, hostdata->connected,
"%s: Last Byte Sent timeout\n", __func__);
return 0;
}
dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
"%s: bus error (%d/%d)\n", __func__, transferred, len);
NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
s = src + transferred;
n = len - transferred;
}
scmd_printk(KERN_ERR, hostdata->connected,
"%s: phase mismatch or !DRQ\n", __func__);
NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
return -1;
}
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 < setup_use_pdma)
return 0;
return cmd->SCp.this_residual;
}
static int macscsi_dma_residual(struct NCR5380_hostdata *hostdata)
{
return hostdata->pdma_residual;
}
#include "NCR5380.c"
#define DRV_MODULE_NAME "mac_scsi"
#define PFX DRV_MODULE_NAME ": "
static struct scsi_host_template mac_scsi_template = {
.module = THIS_MODULE,
.proc_name = DRV_MODULE_NAME,
.name = "Macintosh NCR5380 SCSI",
.info = macscsi_info,
.queuecommand = macscsi_queue_command,
.eh_abort_handler = macscsi_abort,
.eh_host_reset_handler = macscsi_host_reset,
.can_queue = 16,
.this_id = 7,
.sg_tablesize = 1,
.cmd_per_lun = 2,
.dma_boundary = PAGE_SIZE - 1,
.cmd_size = NCR5380_CMD_SIZE,
.max_sectors = 128,
};
static int __init mac_scsi_probe(struct platform_device *pdev)
{
struct Scsi_Host *instance;
struct NCR5380_hostdata *hostdata;
int error;
int host_flags = 0;
struct resource *irq, *pio_mem, *pdma_mem = NULL;
pio_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!pio_mem)
return -ENODEV;
pdma_mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (!hwreg_present((unsigned char *)pio_mem->start +
(STATUS_REG << 4))) {
pr_info(PFX "no device detected at %pap\n", &pio_mem->start);
return -ENODEV;
}
if (setup_can_queue > 0)
mac_scsi_template.can_queue = setup_can_queue;
if (setup_cmd_per_lun > 0)
mac_scsi_template.cmd_per_lun = setup_cmd_per_lun;
if (setup_sg_tablesize >= 0)
mac_scsi_template.sg_tablesize = setup_sg_tablesize;
if (setup_hostid >= 0)
mac_scsi_template.this_id = setup_hostid & 7;
instance = scsi_host_alloc(&mac_scsi_template,
sizeof(struct NCR5380_hostdata));
if (!instance)
return -ENOMEM;
if (irq)
instance->irq = irq->start;
else
instance->irq = NO_IRQ;
hostdata = shost_priv(instance);
hostdata->base = pio_mem->start;
hostdata->io = (u8 __iomem *)pio_mem->start;
if (pdma_mem && setup_use_pdma)
hostdata->pdma_io = (u8 __iomem *)pdma_mem->start;
else
host_flags |= FLAG_NO_PSEUDO_DMA;
host_flags |= setup_toshiba_delay > 0 ? FLAG_TOSHIBA_DELAY : 0;
error = NCR5380_init(instance, host_flags | FLAG_LATE_DMA_SETUP);
if (error)
goto fail_init;
if (instance->irq != NO_IRQ) {
error = request_irq(instance->irq, macscsi_intr, IRQF_SHARED,
"NCR5380", instance);
if (error)
goto fail_irq;
}
NCR5380_maybe_reset_bus(instance);
error = scsi_add_host(instance, NULL);
if (error)
goto fail_host;
platform_set_drvdata(pdev, instance);
scsi_scan_host(instance);
return 0;
fail_host:
if (instance->irq != NO_IRQ)
free_irq(instance->irq, instance);
fail_irq:
NCR5380_exit(instance);
fail_init:
scsi_host_put(instance);
return error;
}
static int __exit mac_scsi_remove(struct platform_device *pdev)
{
struct Scsi_Host *instance = platform_get_drvdata(pdev);
scsi_remove_host(instance);
if (instance->irq != NO_IRQ)
free_irq(instance->irq, instance);
NCR5380_exit(instance);
scsi_host_put(instance);
return 0;
}
static struct platform_driver mac_scsi_driver = {
.remove = __exit_p(mac_scsi_remove),
.driver = {
.name = DRV_MODULE_NAME,
},
};
module_platform_driver_probe(mac_scsi_driver, mac_scsi_probe);
MODULE_ALIAS("platform:" DRV_MODULE_NAME);
MODULE_LICENSE("GPL");
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