linux/drivers/scsi/arm/oak.c
Finn Thain 0a4e361254 ncr5380: Fix soft lockups
Because of the rudimentary design of the chip, it is necessary to poll the
SCSI bus signals during PIO and this tends to hog the CPU. The driver will
accept new commands while others execute, and this causes a soft lockup
because the workqueue item will not terminate until the issue queue is
emptied.

When exercising dmx3191d using sequential IO from dd, the driver is sent
512 KiB WRITE commands and 128 KiB READs. For a PIO transfer, the rate is
is only about 300 KiB/s, so these are long-running commands. And although
PDMA may run at several MiB/s, interrupts are disabled for the duration
of the transfer.

Fix the unresponsiveness and soft lockup issues by calling cond_resched()
after each command is completed and by limiting max_sectors for drivers
that don't implement real DMA.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2016-01-06 21:43:09 -05:00

215 lines
4.2 KiB
C

/*
* Oak Generic NCR5380 driver
*
* Copyright 1995-2002, Russell King
*/
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/blkdev.h>
#include <linux/init.h>
#include <asm/ecard.h>
#include <asm/io.h>
#include <scsi/scsi_host.h>
/*#define PSEUDO_DMA*/
#define DONT_USE_INTR
#define priv(host) ((struct NCR5380_hostdata *)(host)->hostdata)
#define NCR5380_read(reg) \
readb(priv(instance)->base + ((reg) << 2))
#define NCR5380_write(reg, value) \
writeb(value, priv(instance)->base + ((reg) << 2))
#define NCR5380_dma_xfer_len(instance, cmd, phase) (cmd->transfersize)
#define NCR5380_queue_command oakscsi_queue_command
#define NCR5380_info oakscsi_info
#define NCR5380_implementation_fields \
void __iomem *base
#include "../NCR5380.h"
#undef START_DMA_INITIATOR_RECEIVE_REG
#define START_DMA_INITIATOR_RECEIVE_REG (128 + 7)
#define STAT ((128 + 16) << 2)
#define DATA ((128 + 8) << 2)
static inline int NCR5380_pwrite(struct Scsi_Host *instance, unsigned char *addr,
int len)
{
void __iomem *base = priv(instance)->base;
printk("writing %p len %d\n",addr, len);
if(!len) return -1;
while(1)
{
int status;
while (((status = readw(base + STAT)) & 0x100)==0);
}
}
static inline int NCR5380_pread(struct Scsi_Host *instance, unsigned char *addr,
int len)
{
void __iomem *base = priv(instance)->base;
printk("reading %p len %d\n", addr, len);
while(len > 0)
{
unsigned int status, timeout;
unsigned long b;
timeout = 0x01FFFFFF;
while (((status = readw(base + STAT)) & 0x100)==0)
{
timeout--;
if(status & 0x200 || !timeout)
{
printk("status = %08X\n", status);
return 1;
}
}
if(len >= 128)
{
readsw(base + DATA, addr, 128);
addr += 128;
len -= 128;
}
else
{
b = (unsigned long) readw(base + DATA);
*addr ++ = b;
len -= 1;
if(len)
*addr ++ = b>>8;
len -= 1;
}
}
return 0;
}
#undef STAT
#undef DATA
#include "../NCR5380.c"
static struct scsi_host_template oakscsi_template = {
.module = THIS_MODULE,
.name = "Oak 16-bit SCSI",
.info = oakscsi_info,
.queuecommand = oakscsi_queue_command,
.eh_abort_handler = NCR5380_abort,
.eh_bus_reset_handler = NCR5380_bus_reset,
.can_queue = 16,
.this_id = 7,
.sg_tablesize = SG_ALL,
.cmd_per_lun = 2,
.use_clustering = DISABLE_CLUSTERING,
.proc_name = "oakscsi",
.cmd_size = NCR5380_CMD_SIZE,
.max_sectors = 128,
};
static int oakscsi_probe(struct expansion_card *ec, const struct ecard_id *id)
{
struct Scsi_Host *host;
int ret = -ENOMEM;
ret = ecard_request_resources(ec);
if (ret)
goto out;
host = scsi_host_alloc(&oakscsi_template, sizeof(struct NCR5380_hostdata));
if (!host) {
ret = -ENOMEM;
goto release;
}
priv(host)->base = ioremap(ecard_resource_start(ec, ECARD_RES_MEMC),
ecard_resource_len(ec, ECARD_RES_MEMC));
if (!priv(host)->base) {
ret = -ENOMEM;
goto unreg;
}
host->irq = NO_IRQ;
host->n_io_port = 255;
ret = NCR5380_init(host, 0);
if (ret)
goto out_unmap;
NCR5380_maybe_reset_bus(host);
ret = scsi_add_host(host, &ec->dev);
if (ret)
goto out_exit;
scsi_scan_host(host);
goto out;
out_exit:
NCR5380_exit(host);
out_unmap:
iounmap(priv(host)->base);
unreg:
scsi_host_put(host);
release:
ecard_release_resources(ec);
out:
return ret;
}
static void oakscsi_remove(struct expansion_card *ec)
{
struct Scsi_Host *host = ecard_get_drvdata(ec);
ecard_set_drvdata(ec, NULL);
scsi_remove_host(host);
NCR5380_exit(host);
iounmap(priv(host)->base);
scsi_host_put(host);
ecard_release_resources(ec);
}
static const struct ecard_id oakscsi_cids[] = {
{ MANU_OAK, PROD_OAK_SCSI },
{ 0xffff, 0xffff }
};
static struct ecard_driver oakscsi_driver = {
.probe = oakscsi_probe,
.remove = oakscsi_remove,
.id_table = oakscsi_cids,
.drv = {
.name = "oakscsi",
},
};
static int __init oakscsi_init(void)
{
return ecard_register_driver(&oakscsi_driver);
}
static void __exit oakscsi_exit(void)
{
ecard_remove_driver(&oakscsi_driver);
}
module_init(oakscsi_init);
module_exit(oakscsi_exit);
MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("Oak SCSI driver");
MODULE_LICENSE("GPL");