From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753946AbeDRMu0 (ORCPT ); Wed, 18 Apr 2018 08:50:26 -0400 Received: from mail.sysgo.com ([176.9.12.79]:50860 "EHLO mail.sysgo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753902AbeDRMuY (ORCPT ); Wed, 18 Apr 2018 08:50:24 -0400 From: David Engraf To: ludovic.desroches@microchip.com, nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, David Engraf Subject: [PATCH] i2c: at91: Read all available bytes at once Date: Wed, 18 Apr 2018 14:40:55 +0200 Message-Id: <20180418124055.21333-1-david.engraf@sysgo.com> X-Mailer: git-send-email 2.14.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: David Engraf --- drivers/i2c/busses/i2c-at91.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index bfd1fdff64a9..d01c2b2384bd 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -518,8 +518,12 @@ 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 when FIFO is used */ + 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