Re: [PATCH] i2c: exynos5: Preserve high speed master code
From: Krzysztof Kozlowski <krzk@kernel.org>
Date: 2021-02-16 07:53:00
Also in:
linux-i2c, linux-samsung-soc, lkml
On Mon, Feb 15, 2021 at 08:03:21PM +0100, Mårten Lindahl wrote:
From: Mårten Lindahl <redacted> When the controller starts to send a message with the MASTER_ID field set (high speed), the whole I2C_ADDR register is overwritten including MASTER_ID as the SLV_ADDR_MAS field is set.
Are you here describing bug in driver or hardware (the controller?)? Looking at the code, I think the driver, but description got me confused.
quoted hunk ↗ jump to hunk
This patch preserves already written fields in I2C_ADDR when writing SLV_ADDR_MAS. Signed-off-by: Mårten Lindahl <redacted> --- drivers/i2c/busses/i2c-exynos5.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c index 20a9881a0d6c..f2d04c241299 100644 --- a/drivers/i2c/busses/i2c-exynos5.c +++ b/drivers/i2c/busses/i2c-exynos5.c@@ -606,6 +606,7 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop) u32 i2c_ctl; u32 int_en = 0; u32 i2c_auto_conf = 0; + u32 i2c_addr = 0; u32 fifo_ctl; unsigned long flags; unsigned short trig_lvl;@@ -640,7 +641,12 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop) int_en |= HSI2C_INT_TX_ALMOSTEMPTY_EN; } - writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR); + i2c_addr = HSI2C_SLV_ADDR_MAS(i2c->msg->addr); + + if (i2c->op_clock >= I2C_MAX_FAST_MODE_PLUS_FREQ) + i2c_addr |= readl(i2c->regs + HSI2C_ADDR);
Any reason why not "|= MASTER_ID(i2c->adap.nr)" here instead of more expensive IO read? It's quite important because your current code will bitwise-or old I2C slave address with a new one... This should break during tests with multiple I2C slave devices, shouldn't it? On which HW did you test it? Best regards, Krzysztof
+ + writel(i2c_addr, i2c->regs + HSI2C_ADDR);
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