[Qemu-devel] [PATCH] esp: Do not overwrite ESP_TCHI after reset

[Qemu-devel] [PATCH] esp: Do not overwrite ESP_TCHI after reset

[Hannes Reinecke]

After a reset ESP_TCHI should contain the unique ID
of the chip. This value will be overwritten with the
current tranfer count if the transfer count has
previously been set.
The code never checks if the transfer count has
been set, so the unique ID will always be overwritten
if the driver sends a DMA NOP after reset.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 hw/scsi/esp.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 5ab44d8..9798180 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -454,7 +454,9 @@ void esp_reg_write(ESPState *s, uint32_t saddr, uint64_t val)
             /* Reload DMA counter.  */
             s->rregs[ESP_TCLO] = s->wregs[ESP_TCLO];
             s->rregs[ESP_TCMID] = s->wregs[ESP_TCMID];
-            s->rregs[ESP_TCHI] = s->wregs[ESP_TCHI];
+            if (s->wregs[ESP_TCHI]) {
+                    s->rregs[ESP_TCHI] = s->wregs[ESP_TCHI];
+            }
         } else {
             s->dma = 0;
         }
-- 
1.7.12.4

Re: [Qemu-devel] [PATCH] esp: Do not overwrite ESP_TCHI after reset

[Hannes Reinecke]

On 11/10/2014 04:37 PM, Hannes Reinecke wrote:
> After a reset ESP_TCHI should contain the unique ID
> of the chip. This value will be overwritten with the
> current tranfer count if the transfer count has
> previously been set.
> The code never checks if the transfer count has
> been set, so the unique ID will always be overwritten
> if the driver sends a DMA NOP after reset.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  hw/scsi/esp.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
> index 5ab44d8..9798180 100644
> --- a/hw/scsi/esp.c
> +++ b/hw/scsi/esp.c
> @@ -454,7 +454,9 @@ void esp_reg_write(ESPState *s, uint32_t saddr, uint64_t val)
>              /* Reload DMA counter.  */
>              s->rregs[ESP_TCLO] = s->wregs[ESP_TCLO];
>              s->rregs[ESP_TCMID] = s->wregs[ESP_TCMID];
> -            s->rregs[ESP_TCHI] = s->wregs[ESP_TCHI];
> +            if (s->wregs[ESP_TCHI]) {
> +                    s->rregs[ESP_TCHI] = s->wregs[ESP_TCHI];
> +            }
>          } else {
>              s->dma = 0;
>          }
> 
Hmm.
This is actually not quite correct.
I'll be sending an updated patch.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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