From 2b110445b1dfdef34ea7c42c27ddc2ba1bee5753 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Beno=C3=AEt=20Monin?= Date: Wed, 26 Nov 2025 11:46:25 +0100 Subject: [PATCH] i2c: designware: Optimize flag reading in i2c_dw_read() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Optimize the i2c_dw_read() function by reading the message flags only once per message, rather than for every byte. The message flags are accessed both in the outer loop and the inner loop, so move the declaration of the local flags variable to the outer loop. The message index is only modified by the outer loop, so reading the flags in the inner loop was always getting the same value. Reviewed-by: Andy Shevchenko Signed-off-by: Benoît Monin Acked-by: Mika Westerberg Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20251126-i2c-dw-v4-2-b0654598e7c5@bootlin.com --- drivers/i2c/busses/i2c-designware-master.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index 45bfca05bb30..4493568e2fa3 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -593,11 +593,12 @@ i2c_dw_read(struct dw_i2c_dev *dev) unsigned int rx_valid; for (; dev->msg_read_idx < dev->msgs_num; dev->msg_read_idx++) { + u32 flags = msgs[dev->msg_read_idx].flags; unsigned int tmp; u32 len; u8 *buf; - if (!(msgs[dev->msg_read_idx].flags & I2C_M_RD)) + if (!(flags & I2C_M_RD)) continue; if (!(dev->status & STATUS_READ_IN_PROGRESS)) { @@ -611,8 +612,6 @@ i2c_dw_read(struct dw_i2c_dev *dev) regmap_read(dev->map, DW_IC_RXFLR, &rx_valid); for (; len > 0 && rx_valid > 0; len--, rx_valid--) { - u32 flags = msgs[dev->msg_read_idx].flags; - regmap_read(dev->map, DW_IC_DATA_CMD, &tmp); tmp &= DW_IC_DATA_CMD_DAT; /* Ensure length byte is a valid value */ -- 2.47.3