On 01/02/2024 11:36, Paolo Bonzini wrote:
Il gio 1 feb 2024, 12:25 Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk
<mailto:mark.cave-ayl...@ilande.co.uk>> ha scritto:
On 01/02/2024 10:46, Paolo Bonzini wrote:
> On Fri, Jan 12, 2024 at 1:55 PM Mark Cave-Ayland
> <mark.cave-ayl...@ilande.co.uk <mailto:mark.cave-ayl...@ilande.co.uk>>
wrote:
>>
>> Invert the logic so that the end of DMA transfer check becomes one that
checks
>> for TC == 0 in the from device path in do_dma_pdma_cb().
>>
>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk
<mailto:mark.cave-ayl...@ilande.co.uk>>
>> ---
>> hw/scsi/esp.c | 24 +++++++++++-------------
>> 1 file changed, 11 insertions(+), 13 deletions(-)
>>
>> diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
>> index fecfef7c89..63c828c1b2 100644
>> --- a/hw/scsi/esp.c
>> +++ b/hw/scsi/esp.c
>> @@ -602,21 +602,19 @@ static void do_dma_pdma_cb(ESPState *s)
>> return;
>> }
>>
>> - if (esp_get_tc(s) != 0) {
>> - /* Copy device data to FIFO */
>> - len = MIN(s->async_len, esp_get_tc(s));
>> - len = MIN(len, fifo8_num_free(&s->fifo));
>> - fifo8_push_all(&s->fifo, s->async_buf, len);
>> - s->async_buf += len;
>> - s->async_len -= len;
>> - s->ti_size -= len;
>> - esp_set_tc(s, esp_get_tc(s) - len);
>> - return;
>> + if (esp_get_tc(s) == 0) {
>> + esp_lower_drq(s);
>> + esp_dma_done(s);
>> }
>
> I'm only doing a cursory review, but shouldn't there be a return here?
>
> Paolo
(goes and looks)
Possibly there should, but my guess is that adding the return at that
particular
point in time at the series broke one of my reference images. In particular
MacOS is
notorious for requesting data transfers of X len, and setting the TC either
too high
or too low and let the in-built OS recovery logic handle these cases.
Absolutely, just noticing that there is a functional change but the commit message
showed it as a refactoring only.
Would you like me to come up with a reworded commit message here?
The fact that this is bisectable is quite insane, and I am not asking for any code
changes. TBH I wouldn't have blamed you if you just sent a patch to create esp2.c and
a patch to delete esp.c...
Heh... spending a chunk of time rewriting the emulation of a 30 year-old SCSI
controller is probably an odd choice, but the result is something that is
considerably more maintainable than the current implementation. Definitely having a
bisectible history helps in the case of finding a regression, but so far I'd say the
result is a huge improvement on what is already there.
Anything else that you'd like me to change before the series can be considered
for merge?
ATB,
Mark.
