From: David Engraf <david.engraf@sysgo.com> To: ludovic.desroches@microchip.com Cc: nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com, linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, David Engraf <david.engraf@sysgo.com> Subject: [PATCH v2] i2c: at91: Read all available bytes at once Date: Thu, 26 Apr 2018 11:53:14 +0200 [thread overview] Message-ID: <20180426095314.12758-1-david.engraf@sysgo.com> (raw) In-Reply-To: <20180426082558.GX13305@rfolt0960.corp.atmel.com> With FIFO enabled it is possible to read multiple bytes at once in the interrupt handler as long as RXRDY is set. This may also reduce the number of interrupts. This patch polls RXRDY and reads all available bytes at once. Signed-off-by: David Engraf <david.engraf@sysgo.com> --- drivers/i2c/busses/i2c-at91.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index bfd1fdff64a9..9caee5b79eac 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -518,8 +518,16 @@ static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id) * the RXRDY interrupt first in order to not keep garbage data in the * Receive Holding Register for the next transfer. */ - if (irqstatus & AT91_TWI_RXRDY) - at91_twi_read_next_byte(dev); + if (irqstatus & AT91_TWI_RXRDY) { + /* + * Read all available bytes at once by polling RXRDY usable w/ and w/o + * FIFO. With FIFO enabled we could also read RXFL and avoid polling + * RXRDY. + */ + do { + at91_twi_read_next_byte(dev); + } while (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY); + } /* * When a NACK condition is detected, the I2C controller sets the NACK, -- 2.14.1
WARNING: multiple messages have this Message-ID (diff)
From: david.engraf@sysgo.com (David Engraf) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2] i2c: at91: Read all available bytes at once Date: Thu, 26 Apr 2018 11:53:14 +0200 [thread overview] Message-ID: <20180426095314.12758-1-david.engraf@sysgo.com> (raw) In-Reply-To: <20180426082558.GX13305@rfolt0960.corp.atmel.com> With FIFO enabled it is possible to read multiple bytes at once in the interrupt handler as long as RXRDY is set. This may also reduce the number of interrupts. This patch polls RXRDY and reads all available bytes at once. Signed-off-by: David Engraf <david.engraf@sysgo.com> --- drivers/i2c/busses/i2c-at91.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index bfd1fdff64a9..9caee5b79eac 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -518,8 +518,16 @@ static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id) * the RXRDY interrupt first in order to not keep garbage data in the * Receive Holding Register for the next transfer. */ - if (irqstatus & AT91_TWI_RXRDY) - at91_twi_read_next_byte(dev); + if (irqstatus & AT91_TWI_RXRDY) { + /* + * Read all available bytes at once by polling RXRDY usable w/ and w/o + * FIFO. With FIFO enabled we could also read RXFL and avoid polling + * RXRDY. + */ + do { + at91_twi_read_next_byte(dev); + } while (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY); + } /* * When a NACK condition is detected, the I2C controller sets the NACK, -- 2.14.1
next prev parent reply other threads:[~2018-04-26 9:54 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-18 12:40 [PATCH] i2c: at91: Read all available bytes at once David Engraf 2018-04-18 12:40 ` David Engraf 2018-04-25 15:08 ` Ludovic Desroches 2018-04-25 15:08 ` Ludovic Desroches 2018-04-25 15:08 ` Ludovic Desroches 2018-04-25 15:43 ` David Engraf 2018-04-25 15:43 ` David Engraf 2018-04-26 8:25 ` Ludovic Desroches 2018-04-26 8:25 ` Ludovic Desroches 2018-04-26 8:25 ` Ludovic Desroches 2018-04-26 9:53 ` David Engraf [this message] 2018-04-26 9:53 ` [PATCH v2] " David Engraf 2018-04-26 12:30 ` Ludovic Desroches 2018-04-26 12:30 ` Ludovic Desroches 2018-04-26 12:30 ` Ludovic Desroches 2018-04-28 12:38 ` Wolfram Sang 2018-04-28 12:38 ` Wolfram Sang 2018-04-30 6:11 ` David Engraf 2018-04-30 6:11 ` David Engraf 2018-04-26 5:52 ` [PATCH] " David Engraf 2018-04-26 5:52 ` David Engraf
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