sfc: Correct interrupt timer quantum for Siena (normal and turbo mode)
We currently assume that the timer quantum for Siena is 5 us, the same
as for Falcon. This is not correct; timer ticks are generated on a
rota which takes a minimum of 768 cycles (each event delivery or other
timer change will delay it by 3 cycles). The timer quantum should be
6.144 or 3.072 us depending on whether turbo mode is active.
Replace EFX_IRQ_MOD_RESOLUTION with a timer_quantum_ns field in struct
efx_nic, initialised by the efx_nic_type::probe function.
While we're at it, replace EFX_IRQ_MOD_MAX with a timer_period_max
field in struct efx_nic_type.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index de16247..9d4ab5e 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1513,13 +1513,13 @@
*
**************************************************************************/
-static unsigned int irq_mod_ticks(unsigned int usecs, unsigned int resolution)
+static unsigned int irq_mod_ticks(unsigned int usecs, unsigned int quantum_ns)
{
if (usecs == 0)
return 0;
- if (usecs < resolution)
+ if (usecs * 1000 < quantum_ns)
return 1; /* never round down to 0 */
- return usecs / resolution;
+ return usecs * 1000 / quantum_ns;
}
/* Set interrupt moderation parameters */
@@ -1528,14 +1528,20 @@
bool rx_may_override_tx)
{
struct efx_channel *channel;
- unsigned tx_ticks = irq_mod_ticks(tx_usecs, EFX_IRQ_MOD_RESOLUTION);
- unsigned rx_ticks = irq_mod_ticks(rx_usecs, EFX_IRQ_MOD_RESOLUTION);
+ unsigned int irq_mod_max = DIV_ROUND_UP(efx->type->timer_period_max *
+ efx->timer_quantum_ns,
+ 1000);
+ unsigned int tx_ticks;
+ unsigned int rx_ticks;
EFX_ASSERT_RESET_SERIALISED(efx);
- if (tx_ticks > EFX_IRQ_MOD_MAX || rx_ticks > EFX_IRQ_MOD_MAX)
+ if (tx_usecs > irq_mod_max || rx_usecs > irq_mod_max)
return -EINVAL;
+ tx_ticks = irq_mod_ticks(tx_usecs, efx->timer_quantum_ns);
+ rx_ticks = irq_mod_ticks(rx_usecs, efx->timer_quantum_ns);
+
if (tx_ticks != rx_ticks && efx->tx_channel_offset == 0 &&
!rx_may_override_tx) {
netif_err(efx, drv, efx->net_dev, "Channels are shared. "
@@ -1558,8 +1564,14 @@
void efx_get_irq_moderation(struct efx_nic *efx, unsigned int *tx_usecs,
unsigned int *rx_usecs, bool *rx_adaptive)
{
+ /* We must round up when converting ticks to microseconds
+ * because we round down when converting the other way.
+ */
+
*rx_adaptive = efx->irq_rx_adaptive;
- *rx_usecs = efx->irq_rx_moderation * EFX_IRQ_MOD_RESOLUTION;
+ *rx_usecs = DIV_ROUND_UP(efx->irq_rx_moderation *
+ efx->timer_quantum_ns,
+ 1000);
/* If channels are shared between RX and TX, so is IRQ
* moderation. Otherwise, IRQ moderation is the same for all
@@ -1568,9 +1580,10 @@
if (efx->tx_channel_offset == 0)
*tx_usecs = *rx_usecs;
else
- *tx_usecs =
+ *tx_usecs = DIV_ROUND_UP(
efx->channel[efx->tx_channel_offset]->irq_moderation *
- EFX_IRQ_MOD_RESOLUTION;
+ efx->timer_quantum_ns,
+ 1000);
}
/**************************************************************************