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esp.c: consolidate async_len and TC == 0 checks in do_dma_pdma_cb() and esp_do_dma()

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Ensure that the async_len checks for requesting data from the SCSI layer and
the TC == 0 checks to detect the end of the DMA transfer are consistent in both
do_dma_pdma_cb() and esp_do_dma(). In particular this involves adding the check
to see if the FIFO is at its low threshold since PDMA and mixed DMA and non-DMA
requests can leave data remaining in the FIFO.

At the same time update all the comments so that they are also consistent between
all similar code paths.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Helge Deller <deller@gmx.de>
Tested-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20240112125420.514425-29-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
This commit is contained in:
Mark Cave-Ayland 2024-01-12 12:53:20 +00:00
parent a79e767ab1
commit e4e166c8ef
1 changed files with 31 additions and 13 deletions
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44
hw/scsi/esp.c
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@ -604,12 +604,13 @@ static void do_dma_pdma_cb(ESPState *s)
s->async_len -= n;
s->ti_size += n;
if (s->async_len == 0) {
if (s->async_len == 0 && fifo8_num_used(&s->fifo) < 2) {
/* Defer until the scsi layer has completed */
scsi_req_continue(s->current_req);
return;
}
if (esp_get_tc(s) == 0) {
if (esp_get_tc(s) == 0 && fifo8_num_used(&s->fifo) < 2) {
esp_lower_drq(s);
esp_dma_done(s);
}
@ -706,24 +707,30 @@ static void esp_do_dma(ESPState *s)
s->async_len -= len;
s->ti_size += len;
if (s->async_len == 0) {
if (s->async_len == 0 && fifo8_num_used(&s->fifo) < 2) {
/* Defer until the scsi layer has completed */
scsi_req_continue(s->current_req);
/*
* If there is still data to be read from the device then
* complete the DMA operation immediately. Otherwise defer
* until the scsi layer has completed.
*/
return;
}
if (esp_get_tc(s) == 0) {
/* Partially filled a scsi buffer. Complete immediately. */
if (esp_get_tc(s) == 0 && fifo8_num_used(&s->fifo) < 2) {
esp_dma_done(s);
esp_lower_drq(s);
}
} else {
esp_set_pdma_cb(s, DO_DMA_PDMA_CB);
esp_raise_drq(s);
if (s->async_len == 0 && fifo8_num_used(&s->fifo) < 2) {
/* Defer until the scsi layer has completed */
scsi_req_continue(s->current_req);
return;
}
if (esp_get_tc(s) == 0 && fifo8_num_used(&s->fifo) < 2) {
esp_dma_done(s);
esp_lower_drq(s);
}
}
} else {
if (s->dma_memory_write) {
@ -734,13 +741,13 @@ static void esp_do_dma(ESPState *s)
s->async_len -= len;
s->ti_size -= len;
if (s->async_len == 0) {
if (s->async_len == 0 && fifo8_num_used(&s->fifo) < 2) {
/* Defer until the scsi layer has completed */
scsi_req_continue(s->current_req);
return;
}
if (esp_get_tc(s) == 0) {
/* Partially filled a scsi buffer. Complete immediately. */
if (esp_get_tc(s) == 0 && fifo8_num_used(&s->fifo) < 2) {
esp_dma_done(s);
esp_lower_drq(s);
}
@ -754,6 +761,17 @@ static void esp_do_dma(ESPState *s)
esp_set_tc(s, esp_get_tc(s) - len);
esp_set_pdma_cb(s, DO_DMA_PDMA_CB);
esp_raise_drq(s);
if (s->async_len == 0 && fifo8_num_used(&s->fifo) < 2) {
/* Defer until the scsi layer has completed */
scsi_req_continue(s->current_req);
return;
}
if (esp_get_tc(s) == 0 && fifo8_num_used(&s->fifo) < 2) {
esp_lower_drq(s);
esp_dma_done(s);
}
}
}
}