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esp_scsi: use FIFO for command submission 

Using DMA for command submission has the drawback that it might
generate additional DMA completion interrupts after the command
has been submitted to the device.
Additionally the am53c974 has a design flaw causing it
to generate spurious interrupts even though DMA completion
interrupts are not enabled.
This can be avoided by using the FIFO for command submission.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Hannes Reinecke 2014-11-24 15:37:24 +01:00 committed by Christoph Hellwig
parent 9535fff3c5
commit 3170866f88
2 changed files with 30 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
drivers/scsi/esp_scsi.c
View File

@ -143,6 +143,24 @@ void scsi_esp_cmd(struct esp *esp, u8 val)
}
EXPORT_SYMBOL(scsi_esp_cmd);
static void esp_send_dma_cmd(struct esp *esp, int len, int max_len, int cmd)
{
if (esp->flags & ESP_FLAG_USE_FIFO) {
int i;
scsi_esp_cmd(esp, ESP_CMD_FLUSH);
for (i = 0; i < len; i++)
esp_write8(esp->command_block[i], ESP_FDATA);
scsi_esp_cmd(esp, cmd);
} else {
if (esp->rev == FASHME)
scsi_esp_cmd(esp, ESP_CMD_FLUSH);
cmd |= ESP_CMD_DMA;
esp->ops->send_dma_cmd(esp, esp->command_block_dma,
len, max_len, 0, cmd);
}
}
static void esp_event(struct esp *esp, u8 val)
{
struct esp_event_ent *p;
@ -650,10 +668,7 @@ static void esp_autosense(struct esp *esp, struct esp_cmd_entry *ent)
val = (p - esp->command_block);
if (esp->rev == FASHME)
scsi_esp_cmd(esp, ESP_CMD_FLUSH);
esp->ops->send_dma_cmd(esp, esp->command_block_dma,
val, 16, 0, ESP_CMD_DMA | ESP_CMD_SELA);
esp_send_dma_cmd(esp, val, 16, ESP_CMD_SELA);
}
static struct esp_cmd_entry *find_and_prep_issuable_command(struct esp *esp)
@ -789,12 +804,12 @@ build_identify:
}
if (!(esp->flags & ESP_FLAG_DOING_SLOWCMD)) {
start_cmd = ESP_CMD_DMA | ESP_CMD_SELA;
start_cmd = ESP_CMD_SELA;
if (ent->tag[0]) {
*p++ = ent->tag[0];
*p++ = ent->tag[1];
start_cmd = ESP_CMD_DMA | ESP_CMD_SA3;
start_cmd = ESP_CMD_SA3;
}
for (i = 0; i < cmd->cmd_len; i++)
@ -814,7 +829,7 @@ build_identify:
esp->msg_out_len += 2;
}
start_cmd = ESP_CMD_DMA | ESP_CMD_SELAS;
start_cmd = ESP_CMD_SELAS;
esp->select_state = ESP_SELECT_MSGOUT;
}
val = tgt;
@ -834,10 +849,7 @@ build_identify:
printk("]\n");
}
if (esp->rev == FASHME)
scsi_esp_cmd(esp, ESP_CMD_FLUSH);
esp->ops->send_dma_cmd(esp, esp->command_block_dma,
val, 16, 0, start_cmd);
esp_send_dma_cmd(esp, val, 16, start_cmd);
}
static struct esp_cmd_entry *esp_get_ent(struct esp *esp)
@ -1646,7 +1658,7 @@ static int esp_msgin_process(struct esp *esp)
static int esp_process_event(struct esp *esp)
{
int write;
int write, i;
again:
write = 0;
@ -1872,6 +1884,10 @@ again:
if (esp->msg_out_len == 1) {
esp_write8(esp->msg_out[0], ESP_FDATA);
scsi_esp_cmd(esp, ESP_CMD_TI);
} else if (esp->flags & ESP_FLAG_USE_FIFO) {
for (i = 0; i < esp->msg_out_len; i++)
esp_write8(esp->msg_out[i], ESP_FDATA);
scsi_esp_cmd(esp, ESP_CMD_TI);
} else {
/* Use DMA. */
memcpy(esp->command_block,
@ -1949,11 +1965,7 @@ again:
case ESP_EVENT_CMD_START:
memcpy(esp->command_block, esp->cmd_bytes_ptr,
esp->cmd_bytes_left);
if (esp->rev == FASHME)
scsi_esp_cmd(esp, ESP_CMD_FLUSH);
esp->ops->send_dma_cmd(esp, esp->command_block_dma,
esp->cmd_bytes_left, 16, 0,
ESP_CMD_DMA | ESP_CMD_TI);
esp_send_dma_cmd(esp, esp->cmd_bytes_left, 16, ESP_CMD_TI);
esp_event(esp, ESP_EVENT_CMD_DONE);
esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
break;

1
drivers/scsi/esp_scsi.h
View File

@ -478,6 +478,7 @@ struct esp {
#define ESP_FLAG_WIDE_CAPABLE 0x00000008
#define ESP_FLAG_QUICKIRQ_CHECK 0x00000010
#define ESP_FLAG_DISABLE_SYNC 0x00000020
#define ESP_FLAG_USE_FIFO 0x00000040
u8 select_state;
#define ESP_SELECT_NONE 0x00 /* Not selecting */