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@xxxxxxxxxx>
Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
drivers/scsi/esp_scsi.c | 46 +++++++++++++++++++++++++++++-----------------
drivers/scsi/esp_scsi.h | 1 +
2 files changed, 30 insertions(+), 17 deletions(-)
diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 0ad0f08..2a3277d 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -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;
diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
index 975d293..27dcaf8 100644
--- a/drivers/scsi/esp_scsi.h
+++ b/drivers/scsi/esp_scsi.h
@@ -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 */
--
1.8.5.2
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