From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiner Kallweit Subject: [PATCH v2 06/09] spi: fsl-espi: make better use of the RX FIFO Date: Thu, 27 Oct 2016 21:27:56 +0200 Message-ID: <082fee3f-4623-2cca-803b-b0fdf7cc8ab1@gmail.com> References: <5b98be38-17a2-79a2-14da-fb2bb6f8820f@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: "linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" To: Mark Brown Return-path: In-Reply-To: <5b98be38-17a2-79a2-14da-fb2bb6f8820f-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: So far an interrupt is triggered whenever there's at least one byte in the RX FIFO. This results in a unnecessarily high number of interrupts. Change this to generate an interrupt if - RX FIFO is half full (except if all bytes to read fit into the RX FIFO anyway) - end of transfer has been reached This way the number of interrupts can be significantly reduced. Signed-off-by: Heiner Kallweit --- v2: - rebased --- drivers/spi/spi-fsl-espi.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c index ca14575..06fb185 100644 --- a/drivers/spi/spi-fsl-espi.c +++ b/drivers/spi/spi-fsl-espi.c @@ -55,9 +55,10 @@ #define CSMODE_CG(x) ((x) << 3) #define FSL_ESPI_FIFO_SIZE 32 +#define FSL_ESPI_RXTHR 15 /* Default mode/csmode for eSPI controller */ -#define SPMODE_INIT_VAL (SPMODE_TXTHR(4) | SPMODE_RXTHR(3)) +#define SPMODE_INIT_VAL (SPMODE_TXTHR(4) | SPMODE_RXTHR(FSL_ESPI_RXTHR)) #define CSMODE_INIT_VAL (CSMODE_POL_1 | CSMODE_BEF(0) \ | CSMODE_AFT(0) | CSMODE_CG(1)) @@ -281,6 +282,7 @@ static void fsl_espi_setup_transfer(struct spi_device *spi, static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t) { struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master); + u32 mask; int ret; mpc8xxx_spi->rx_len = t->len; @@ -295,8 +297,11 @@ static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t) fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPCOM, (SPCOM_CS(spi->chip_select) | SPCOM_TRANLEN(t->len - 1))); - /* enable rx ints */ - fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPIM, SPIM_RNE); + /* enable interrupts */ + mask = SPIM_DON; + if (mpc8xxx_spi->rx_len > FSL_ESPI_FIFO_SIZE) + mask |= SPIM_RXT; + fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPIM, mask); /* Prevent filling the fifo from getting interrupted */ spin_lock_irq(&mpc8xxx_spi->lock); -- 2.10.1 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html