From: Krzysztof Kozlowski <krzk@kernel.org>
To: "Mårten Lindahl" <marten.lindahl@axis.com>
Cc: kernel@axis.com, "Mårten Lindahl" <martenli@axis.com>,
linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i2c: exynos5: Preserve high speed master code
Date: Tue, 16 Feb 2021 08:51:41 +0100 [thread overview]
Message-ID: <20210216075141.o4wjnwmmjze2p3cn@kozik-lap> (raw)
In-Reply-To: <20210215190322.22094-1-marten.lindahl@axis.com>
On Mon, Feb 15, 2021 at 08:03:21PM +0100, Mårten Lindahl wrote:
> From: Mårten Lindahl <martenli@axis.com>
>
> 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.
>
> This patch preserves already written fields in I2C_ADDR when writing
> SLV_ADDR_MAS.
>
> Signed-off-by: Mårten Lindahl <martenli@axis.com>
> ---
> 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);
next prev parent reply other threads:[~2021-02-16 7:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-15 19:03 [PATCH] i2c: exynos5: Preserve high speed master code Mårten Lindahl
2021-02-16 7:51 ` Krzysztof Kozlowski [this message]
2021-02-16 22:09 ` Marten Lindahl
2021-02-17 8:07 ` Krzysztof Kozlowski
2021-02-17 8:32 ` Jesper Nilsson
2021-02-17 8:43 ` Krzysztof Kozlowski
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