Re: [PULL V2 01/23] dp8393x: Mask EOL bit from descriptor addresses

[Finn Thain]

Hi Jason,

The patch in this pull request (since merged) differs from the patch that 
I sent. In particular, the change below is missing from commit 88f632fbb1 
("dp8393x: Mask EOL bit from descriptor addresses") in mainline.

--- a/hw/net/dp8393x.c
+++ b/hw/net/dp8393x.c
@@ -525,8 +525,8 @@ static void dp8393x_do_transmit_packets(dp8393xState *s)
                                  * (4 + 3 * s->regs[SONIC_TFC]),
                                MEMTXATTRS_UNSPECIFIED, s->data,
                                size);
-            s->regs[SONIC_CTDA] = dp8393x_get(s, width, 0) & ~0x1;
-            if (dp8393x_get(s, width, 0) & SONIC_DESC_EOL) {
+            s->regs[SONIC_CTDA] = dp8393x_get(s, width, 0);
+            if (s->regs[SONIC_CTDA] & SONIC_DESC_EOL) {
                 /* EOL detected */
                 break;
             }

Please compare with "[PATCH v4 01/14] dp8393x: Mask EOL bit from 
descriptor addresses" in the mailing list archives: 
https://lore.kernel.org/qemu-devel/address@hidden/

It appears that this portion of my patch went missing when merge conflicts 
were resolved. The conflicts were apparently caused by commit 19f7034773 
("Avoid address_space_rw() with a constant is_write argument").

Regards,
Finn

On Tue, 3 Mar 2020, Jason Wang wrote:

> From: Finn Thain <address@hidden>
> 
> The Least Significant bit of a descriptor address register is used as
> an EOL flag. It has to be masked when the register value is to be used
> as an actual address for copying memory around. But when the registers
> are to be updated the EOL bit should not be masked.
> 
> Signed-off-by: Finn Thain <address@hidden>
> Tested-by: Laurent Vivier <address@hidden>
> Signed-off-by: Jason Wang <address@hidden>
> ---
>  hw/net/dp8393x.c | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
> index 7045193..216d44b 100644
> --- a/hw/net/dp8393x.c
> +++ b/hw/net/dp8393x.c
> @@ -145,6 +145,9 @@ do { printf("sonic ERROR: %s: " fmt, __func__ , ## 
> __VA_ARGS__); } while (0)
>  #define SONIC_ISR_PINT   0x0800
>  #define SONIC_ISR_LCD    0x1000
>  
> +#define SONIC_DESC_EOL   0x0001
> +#define SONIC_DESC_ADDR  0xFFFE
> +
>  #define TYPE_DP8393X "dp8393x"
>  #define DP8393X(obj) OBJECT_CHECK(dp8393xState, (obj), TYPE_DP8393X)
>  
> @@ -197,7 +200,8 @@ static uint32_t dp8393x_crba(dp8393xState *s)
>  
>  static uint32_t dp8393x_crda(dp8393xState *s)
>  {
> -    return (s->regs[SONIC_URDA] << 16) | s->regs[SONIC_CRDA];
> +    return (s->regs[SONIC_URDA] << 16) |
> +           (s->regs[SONIC_CRDA] & SONIC_DESC_ADDR);
>  }
>  
>  static uint32_t dp8393x_rbwc(dp8393xState *s)
> @@ -217,7 +221,8 @@ static uint32_t dp8393x_tsa(dp8393xState *s)
>  
>  static uint32_t dp8393x_ttda(dp8393xState *s)
>  {
> -    return (s->regs[SONIC_UTDA] << 16) | s->regs[SONIC_TTDA];
> +    return (s->regs[SONIC_UTDA] << 16) |
> +           (s->regs[SONIC_TTDA] & SONIC_DESC_ADDR);
>  }
>  
>  static uint32_t dp8393x_wt(dp8393xState *s)
> @@ -509,7 +514,7 @@ static void dp8393x_do_transmit_packets(dp8393xState *s)
>                                 MEMTXATTRS_UNSPECIFIED, s->data,
>                                 size);
>              s->regs[SONIC_CTDA] = dp8393x_get(s, width, 0) & ~0x1;
> -            if (dp8393x_get(s, width, 0) & 0x1) {
> +            if (dp8393x_get(s, width, 0) & SONIC_DESC_EOL) {
>                  /* EOL detected */
>                  break;
>              }
> @@ -765,13 +770,13 @@ static ssize_t dp8393x_receive(NetClientState *nc, 
> const uint8_t * buf,
>      /* XXX: Check byte ordering */
>  
>      /* Check for EOL */
> -    if (s->regs[SONIC_LLFA] & 0x1) {
> +    if (s->regs[SONIC_LLFA] & SONIC_DESC_EOL) {
>          /* Are we still in resource exhaustion? */
>          size = sizeof(uint16_t) * 1 * width;
>          address = dp8393x_crda(s) + sizeof(uint16_t) * 5 * width;
>          address_space_read(&s->as, address, MEMTXATTRS_UNSPECIFIED,
>                             s->data, size);
> -        if (dp8393x_get(s, width, 0) & 0x1) {
> +        if (dp8393x_get(s, width, 0) & SONIC_DESC_EOL) {
>              /* Still EOL ; stop reception */
>              return -1;
>          } else {
> @@ -831,7 +836,7 @@ static ssize_t dp8393x_receive(NetClientState *nc, const 
> uint8_t * buf,
>                         dp8393x_crda(s) + sizeof(uint16_t) * 5 * width,
>                         MEMTXATTRS_UNSPECIFIED, s->data, size);
>      s->regs[SONIC_LLFA] = dp8393x_get(s, width, 0);
> -    if (s->regs[SONIC_LLFA] & 0x1) {
> +    if (s->regs[SONIC_LLFA] & SONIC_DESC_EOL) {
>          /* EOL detected */
>          s->regs[SONIC_ISR] |= SONIC_ISR_RDE;
>      } else {
>