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[Qemu-devel] [PULL 06/17] hw/net/stellaris_enet: Correctly implement the
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PULL 06/17] hw/net/stellaris_enet: Correctly implement the TR and THR registers |
Date: |
Tue, 13 May 2014 16:31:28 +0100 |
Packet transmission for the stellaris ethernet controller can be triggered
in one of two ways:
* by setting a threshold value in the THR register; when the FIFO
fill level reaches the threshold, the h/w starts transmitting.
Software has to finish filling the FIFO before the transmit
process completes to avoid a (silent) underrun
* by software writing to the TR register to explicitly trigger
transmission
Since QEMU transmits packets instantaneously (from the guest's
point of view), implement "transmit based on threshold" with
our existing mechanism of "transmit as soon as we have the whole
packet", with the additional wrinkle that we don't transmit if
the packet size is below the specified threshold, and implement
"transmit by specific request" properly.
Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
---
hw/net/stellaris_enet.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/hw/net/stellaris_enet.c b/hw/net/stellaris_enet.c
index b99f93e..2079fc6 100644
--- a/hw/net/stellaris_enet.c
+++ b/hw/net/stellaris_enet.c
@@ -109,6 +109,15 @@ static inline bool
stellaris_txpacket_complete(stellaris_enet_state *s)
return s->tx_fifo_len >= framelen;
}
+/* Return true if the TX FIFO threshold is enabled and the FIFO
+ * has filled enough to reach it.
+ */
+static inline bool stellaris_tx_thr_reached(stellaris_enet_state *s)
+{
+ return (s->thr < 0x3f &&
+ (s->tx_fifo_len >= 4 * (s->thr * 8 + 1)));
+}
+
/* Send the packet currently in the TX FIFO */
static void stellaris_enet_send(stellaris_enet_state *s)
{
@@ -309,7 +318,7 @@ static void stellaris_enet_write(void *opaque, hwaddr
offset,
s->tx_fifo[s->tx_fifo_len++] = value >> 24;
}
- if (stellaris_txpacket_complete(s)) {
+ if (stellaris_tx_thr_reached(s) && stellaris_txpacket_complete(s)) {
stellaris_enet_send(s);
}
break;
@@ -338,9 +347,13 @@ static void stellaris_enet_write(void *opaque, hwaddr
offset,
case 0x2c: /* MTXD */
s->mtxd = value & 0xff;
break;
+ case 0x38: /* TR */
+ if (value & 1) {
+ stellaris_enet_send(s);
+ }
+ break;
case 0x30: /* MRXD */
case 0x34: /* NP */
- case 0x38: /* TR */
/* Ignored. */
case 0x3c: /* Undocuented: Timestamp? */
/* Ignored. */
--
1.9.2
- [Qemu-devel] [PULL 17/17] hw/arm/omap_gpmc: Avoid buffer overrun filling prefetch FIFO, (continued)
- [Qemu-devel] [PULL 17/17] hw/arm/omap_gpmc: Avoid buffer overrun filling prefetch FIFO, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 12/17] hw/net/cadence_gem: Remove dead code, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 09/17] hw/net/stellaris_enet: Convert to vmstate, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 15/17] hw/timer/exynos4210_mct: Avoid overflow in exynos4210_ltick_recalc_count, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 03/17] hw/net/stellaris_enet: Restructure tx_fifo code to avoid buffer overrun, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 14/17] hw/dma/omap_dma: Add (uint32_t) casts when shifting uint16_t by 16, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 16/17] hw/arm/stellaris: Correct handling of GPTM TAR register, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 10/17] target-arm/helper.c: Don't flush the TLB if SCTLR is rewritten unchanged, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 13/17] hw/arm/omap1: Avoid unintended sign extension writing omap_rtc YEARS_REG, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 11/17] hw/intc/allwinner-a10-pic: Add missing 'break', Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 06/17] hw/net/stellaris_enet: Correctly implement the TR and THR registers,
Peter Maydell <=
- [Qemu-devel] [PULL 05/17] hw/net/stellaris_enet: Rewrite tx fifo handling code, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 08/17] hw/net/stellaris_enet: Get rid of rx_fifo pointer, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 04/17] hw/net/stellaris_enet: Correct handling of packet padding, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 07/17] hw/net/stellaris_enet: Fix debug format strings, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 01/17] disas/libvixl: Update to libvixl 1.4, Peter Maydell, 2014/05/13
- [Qemu-devel] [PULL 02/17] savevm: Remove all the unneeded version_minimum_id_old (arm), Peter Maydell, 2014/05/13
- Re: [Qemu-devel] [PULL 00/17] target-arm queue, Peter Maydell, 2014/05/15