From 0e59378bc05b084939af54d2066552ac42fa0fee Mon Sep 17 00:00:00 2001 From: Sifan Naeem Date: Thu, 10 Sep 2015 15:50:01 +0100 Subject: [PATCH] i2c: img-scb: enable fencing for all versions of the ip The code to read from the master read fifo, and write to the master write fifo, checks a bit in an SCB register before every byte to ensure that the fifo is not full (write fifo) or empty (read fifo). Due to clock domain crossing inside the SCB block the updated value of this bit is only visible after 2 cycles. The scb_wr_rd_fence() function does 2 dummy writes (to the read-only revision register), and it's called before reading from or writing to the fifos to ensure that subsequent reads of the fifo status bits do not read stale values. As the 2 dummy writes are required in all versions of the ip, the version check is dropped. Fixes: commit 27bce457d588 ("i2c: img-scb: Add Imagination Technologies I2C SCB driver") Signed-off-by: Sifan Naeem Acked-by: James Hogan Reviewed-by: James Hartley Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-img-scb.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c index 00ffd6613680..5c3c61586d4a 100644 --- a/drivers/i2c/busses/i2c-img-scb.c +++ b/drivers/i2c/busses/i2c-img-scb.c @@ -278,8 +278,6 @@ #define ISR_COMPLETE(err) (ISR_COMPLETE_M | (ISR_STATUS_M & (err))) #define ISR_FATAL(err) (ISR_COMPLETE(err) | ISR_FATAL_M) -#define REL_SOC_IP_SCB_2_2_1 0x00020201 - enum img_i2c_mode { MODE_INACTIVE, MODE_RAW, @@ -1120,10 +1118,8 @@ static int img_i2c_init(struct img_i2c *i2c) return -EINVAL; } - if (rev == REL_SOC_IP_SCB_2_2_1) { - i2c->need_wr_rd_fence = true; - dev_info(i2c->adap.dev.parent, "fence quirk enabled"); - } + /* Fencing enabled by default. */ + i2c->need_wr_rd_fence = true; bitrate_khz = i2c->bitrate / 1000; clk_khz = clk_get_rate(i2c->scb_clk) / 1000; -- 2.20.1