From: Ursula Maplehurst <urs...@kangatronix.co.uk> Reduce the number of separate SPI core requests when setting the UINC bit in the RX FIFO, and instead batch them up into a single SPI core request.
Link: https://github.com/marckleinebudde/linux/issues/4 Link: https://lore.kernel.org/r/20201126132144.351154-3-...@pengutronix.de Tested-by: Thomas Kopp <thomas.k...@microchip.com> Signed-off-by: Ursula Maplehurst <urs...@kangatronix.co.uk> Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de> --- .../net/can/spi/mcp251xfd/mcp251xfd-core.c | 51 ++++++++++++++++--- drivers/net/can/spi/mcp251xfd/mcp251xfd.h | 2 + 2 files changed, 45 insertions(+), 8 deletions(-) diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c index 476a2e4a1de8..c770733ecbcc 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c @@ -332,7 +332,7 @@ static void mcp251xfd_ring_init(struct mcp251xfd_priv *priv) u32 val; u16 addr; u8 len; - int i; + int i, j; /* TEF */ priv->tef.head = 0; @@ -370,6 +370,23 @@ static void mcp251xfd_ring_init(struct mcp251xfd_priv *priv) prev_rx_ring->obj_num; prev_rx_ring = rx_ring; + + /* FIFO increment RX tail pointer */ + addr = MCP251XFD_REG_FIFOCON(rx_ring->fifo_nr); + val = MCP251XFD_REG_FIFOCON_UINC; + len = mcp251xfd_cmd_prepare_write_reg(priv, &rx_ring->uinc_buf, + addr, val, val); + + for (j = 0; j < ARRAY_SIZE(rx_ring->uinc_xfer); j++) { + struct spi_transfer *xfer; + + xfer = &rx_ring->uinc_xfer[j]; + xfer->tx_buf = &rx_ring->uinc_buf; + xfer->len = len; + xfer->cs_change = 1; + xfer->cs_change_delay.value = 0; + xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS; + } } } @@ -1440,13 +1457,7 @@ mcp251xfd_handle_rxif_one(struct mcp251xfd_priv *priv, if (err) stats->rx_fifo_errors++; - ring->tail++; - - /* finally increment the RX pointer */ - return regmap_update_bits(priv->map_reg, - MCP251XFD_REG_FIFOCON(ring->fifo_nr), - GENMASK(15, 8), - MCP251XFD_REG_FIFOCON_UINC); + return 0; } static inline int @@ -1478,6 +1489,8 @@ mcp251xfd_handle_rxif_ring(struct mcp251xfd_priv *priv, return err; while ((len = mcp251xfd_get_rx_linear_len(ring))) { + struct spi_transfer *last_xfer; + rx_tail = mcp251xfd_get_rx_tail(ring); err = mcp251xfd_rx_obj_read(priv, ring, hw_rx_obj, @@ -1492,6 +1505,28 @@ mcp251xfd_handle_rxif_ring(struct mcp251xfd_priv *priv, if (err) return err; } + + /* Increment the RX FIFO tail pointer 'len' times in a + * single SPI message. + */ + ring->tail += len; + + /* Note: + * + * "cs_change == 1" on the last transfer results in an + * active chip select after the complete SPI + * message. This causes the controller to interpret + * the next register access as data. Temporary set + * "cs_change" of the last transfer to "0" to properly + * deactivate the chip select at the end of the + * message. + */ + last_xfer = &ring->uinc_xfer[len - 1]; + last_xfer->cs_change = 0; + err = spi_sync_transfer(priv->spi, ring->uinc_xfer, len); + last_xfer->cs_change = 1; + if (err) + return err; } return 0; diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h index c20c97d01072..97dc182e2b42 100644 --- a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h +++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h @@ -528,6 +528,8 @@ struct mcp251xfd_rx_ring { u8 obj_num; u8 obj_size; + union mcp251xfd_write_reg_buf uinc_buf; + struct spi_transfer uinc_xfer[MCP251XFD_RX_OBJ_NUM_MAX]; struct mcp251xfd_hw_rx_obj_canfd obj[]; }; -- 2.29.2
