Re: [PATCH v3 13/14] dp8393x: Don't reset Silicon Revision register

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 1/19/20 11:59 PM, Finn Thain wrote:
> The jazzsonic driver in Linux uses the Silicon Revision register value
> to probe the chip. The driver fails unless the SR register contains 4.
> Unfortunately, reading this register in QEMU usually returns 0 because
> the s->regs[] array gets wiped after a software reset.
> 
> Fixes: bd8f1ebce4 ("net/dp8393x: fix hardware reset")
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> ---
>   hw/net/dp8393x.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
> index 1b73a8703b..71af0fad51 100644
> --- a/hw/net/dp8393x.c
> +++ b/hw/net/dp8393x.c
> @@ -591,6 +591,10 @@ static uint64_t dp8393x_read(void *opaque, hwaddr addr, unsigned int size)
>                   val |= s->cam[s->regs[SONIC_CEP] & 0xf][2* (SONIC_CAP0 - reg)];
>               }
>               break;
> +        /* Read-only */
> +        case SONIC_SR:
> +            val = 4; /* only revision recognized by Linux/mips */
> +            break;
>           /* All other registers have no special contrainst */
>           default:
>               val = s->regs[reg];
> @@ -971,7 +975,6 @@ static void dp8393x_realize(DeviceState *dev, Error **errp)
>       qemu_format_nic_info_str(qemu_get_queue(s->nic), s->conf.macaddr.a);
>   
>       s->watchdog = timer_new_ns(QEMU_CLOCK_VIRTUAL, dp8393x_watchdog, s);
> -    s->regs[SONIC_SR] = 0x0004; /* only revision recognized by Linux */
>   
>       memory_region_init_ram(&s->prom, OBJECT(dev),
>                              "dp8393x-prom", SONIC_PROM_SIZE, &local_err);
> 

Please fix in dp8393x_reset() instead:

-- >8 --
diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
index cdc2631c0c..65eb9c23a7 100644
--- a/hw/net/dp8393x.c
+++ b/hw/net/dp8393x.c
@@ -862,6 +862,7 @@ static void dp8393x_reset(DeviceState *dev)
      timer_del(s->watchdog);

      memset(s->regs, 0, sizeof(s->regs));
+    s->regs[SONIC_SR] = 0x0004; /* only revision recognized by Linux */
      s->regs[SONIC_CR] = SONIC_CR_RST | SONIC_CR_STP | SONIC_CR_RXDIS;
      s->regs[SONIC_DCR] &= ~(SONIC_DCR_EXBUS | SONIC_DCR_LBR);
      s->regs[SONIC_RCR] &= ~(SONIC_RCR_LB0 | SONIC_RCR_LB1 | 
SONIC_RCR_BRD | SONIC_RCR_RNT);
@@ -914,7 +915,6 @@ static void dp8393x_realize(DeviceState *dev, Error 
**errp)
      qemu_format_nic_info_str(qemu_get_queue(s->nic), s->conf.macaddr.a);

      s->watchdog = timer_new_ns(QEMU_CLOCK_VIRTUAL, dp8393x_watchdog, s);
-    s->regs[SONIC_SR] = 0x0004; /* only revision recognized by Linux */

      memory_region_init_ram(&s->prom, OBJECT(dev),
                             "dp8393x-prom", SONIC_PROM_SIZE, &local_err);
---