diff options
Diffstat (limited to 'target/linux/brcm2708/patches-3.18/0020-Perform-I2C-combined-transactions-when-possible.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-3.18/0020-Perform-I2C-combined-transactions-when-possible.patch | 72 |
1 files changed, 0 insertions, 72 deletions
diff --git a/target/linux/brcm2708/patches-3.18/0020-Perform-I2C-combined-transactions-when-possible.patch b/target/linux/brcm2708/patches-3.18/0020-Perform-I2C-combined-transactions-when-possible.patch deleted file mode 100644 index c31848d..0000000 --- a/target/linux/brcm2708/patches-3.18/0020-Perform-I2C-combined-transactions-when-possible.patch +++ /dev/null @@ -1,72 +0,0 @@ -From 0262abfaac71799e3688285f1f30bead42b8ff7e Mon Sep 17 00:00:00 2001 -From: cbeytas <cbeytas@shaw.ca> -Date: Mon, 24 Jun 2013 00:05:40 -0400 -Subject: [PATCH 020/114] Perform I2C combined transactions when possible - -Perform I2C combined transactions whenever possible, within the -restrictions of the Broadcomm Serial Controller. - -Disable DONE interrupt during TA poll - -Prevent interrupt from being triggered if poll is missed and transfer -starts and finishes. - -i2c: Make combined transactions optional and disabled by default ---- - drivers/i2c/busses/i2c-bcm2708.c | 31 ++++++++++++++++++++++++++++++- - 1 file changed, 30 insertions(+), 1 deletion(-) - ---- a/drivers/i2c/busses/i2c-bcm2708.c -+++ b/drivers/i2c/busses/i2c-bcm2708.c -@@ -74,6 +74,9 @@ static unsigned int baudrate = CONFIG_I2 - module_param(baudrate, uint, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); - MODULE_PARM_DESC(baudrate, "The I2C baudrate"); - -+static bool combined = false; -+module_param(combined, bool, 0644); -+MODULE_PARM_DESC(combined, "Use combined transactions"); - - struct bcm2708_i2c { - struct i2c_adapter adapter; -@@ -150,7 +153,7 @@ static inline void bcm2708_bsc_fifo_fill - static inline void bcm2708_bsc_setup(struct bcm2708_i2c *bi) - { - unsigned long bus_hz; -- u32 cdiv; -+ u32 cdiv, s; - u32 c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_ST | BSC_C_CLEAR_1; - - bus_hz = clk_get_rate(bi->clk); -@@ -166,6 +169,32 @@ static inline void bcm2708_bsc_setup(str - bcm2708_wr(bi, BSC_DIV, cdiv); - bcm2708_wr(bi, BSC_A, bi->msg->addr); - bcm2708_wr(bi, BSC_DLEN, bi->msg->len); -+ if (combined) -+ { -+ /* Do the next two messages meet combined transaction criteria? -+ - Current message is a write, next message is a read -+ - Both messages to same slave address -+ - Write message can fit inside FIFO (16 bytes or less) */ -+ if ( (bi->nmsgs > 1) && -+ !(bi->msg[0].flags & I2C_M_RD) && (bi->msg[1].flags & I2C_M_RD) && -+ (bi->msg[0].addr == bi->msg[1].addr) && (bi->msg[0].len <= 16)) { -+ /* Fill FIFO with entire write message (16 byte FIFO) */ -+ while (bi->pos < bi->msg->len) -+ bcm2708_wr(bi, BSC_FIFO, bi->msg->buf[bi->pos++]); -+ /* Start write transfer (no interrupts, don't clear FIFO) */ -+ bcm2708_wr(bi, BSC_C, BSC_C_I2CEN | BSC_C_ST); -+ /* poll for transfer start bit (should only take 1-20 polls) */ -+ do { -+ s = bcm2708_rd(bi, BSC_S); -+ } while (!(s & (BSC_S_TA | BSC_S_ERR | BSC_S_CLKT | BSC_S_DONE))); -+ /* Send next read message before the write transfer finishes. */ -+ bi->nmsgs--; -+ bi->msg++; -+ bi->pos = 0; -+ bcm2708_wr(bi, BSC_DLEN, bi->msg->len); -+ c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_INTR | BSC_C_ST | BSC_C_READ; -+ } -+ } - bcm2708_wr(bi, BSC_C, c); - } - |