[PATCH V7 06/10] can: mcp25xxfd: optimize TEF read avoiding unnecessary SPI transfers
From: <hidden>
Date: 2019-02-21 21:07:32
Subsystem:
can network drivers, the rest · Maintainers:
Marc Kleine-Budde, Vincent Mailhol, Linus Torvalds
From: Martin Sperl <redacted> We have already enough information to know how many tx-messages have been terminated so that we do not have to query TEF every time if there is anything pending but we can read the tefs blindly. This avoids 1 SPI transfer per TEF read. Signed-off-by: Martin Sperl <redacted> --- drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.c | 33 ++++++++++++++++++++++++ 1 file changed, 33 insertions(+)
diff --git a/drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.c b/drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.c
index 04c32b91cee1..0d08bc9768d9 100644
--- a/drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.c
+++ b/drivers/net/can/spi/mcp25xxfd/mcp25xxfd_can_tx.c@@ -274,6 +274,13 @@ int mcp25xxfd_can_tx_handle_int_tefif_fifo(struct mcp25xxfd_can_priv *cpriv) MCP25XXFD_CAN_TEFCON_UINC); } +/* reading TEF entries can be made even more efficient by reading + * multiple TEF entries in one go. + * Under the assumption that we have count(TEF) >= count(TX_FIFO) + * we can even release TEFs early (before we read them) + * (and potentially restarting the transmit-queue early aswell) + */ + static int mcp25xxfd_can_tx_handle_int_tefif_conservative(struct mcp25xxfd_can_priv *cpriv) {
@@ -304,6 +311,25 @@ mcp25xxfd_can_tx_handle_int_tefif_conservative(struct mcp25xxfd_can_priv *cpriv) return 0; } +static int +mcp25xxfd_can_tx_handle_int_tefif_optimized(struct mcp25xxfd_can_priv *cpriv, + u32 finished) +{ + int i, fifo, ret; + + /* now iterate those */ + for (i = 0, fifo = cpriv->fifos.tx.start; i < cpriv->fifos.tx.count; + i++, fifo++) { + if (finished & BIT(fifo)) { + ret = mcp25xxfd_can_tx_handle_int_tefif_fifo(cpriv); + if (ret) + return ret; + } + } + + return 0; +} + int mcp25xxfd_can_tx_handle_int_tefif(struct mcp25xxfd_can_priv *cpriv) { unsigned long flags;
@@ -323,6 +349,13 @@ int mcp25xxfd_can_tx_handle_int_tefif(struct mcp25xxfd_can_priv *cpriv) spin_unlock_irqrestore(&cpriv->fifos.tx_queue->lock, flags); + /* run in optimized mode if possible */ + if (finished) + return mcp25xxfd_can_tx_handle_int_tefif_optimized(cpriv, + finished); + /* otherwise play it safe */ + netdev_warn(cpriv->can.dev, + "Something is wrong - we got a TEF interrupt but we were not able to detect a finished fifo\n"); return mcp25xxfd_can_tx_handle_int_tefif_conservative(cpriv); } --
2.11.0