From: Marten Lindahl <martenli@axis.com>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: linux-samsung-soc@vger.kernel.org, kernel@axis.com,
linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i2c: exynos5: Preserve high speed master code
Date: Tue, 16 Feb 2021 23:09:33 +0100 [thread overview]
Message-ID: <20210216220933.2wzmft72bhjptzl3@axis.com> (raw)
In-Reply-To: <20210216075141.o4wjnwmmjze2p3cn@kozik-lap>
Hi Krzysztof!
Thank you for your comments! Please see my reply below.
I will send v2 in a moment.
On Tue, Feb 16, 2021 at 08:51:41AM +0100, Krzysztof Kozlowski wrote:
> 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.
>
Yes, it is the driver. I will change.
> >
> > 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?
>
You are correct. It is better to use the macro instead, and yes,
safer too. I only have one device that supports high speed i2c, but
I get your point. It could potentially break.
> On which HW did you test it?
I used an Artpec development board as master and INA230EVM board
as slave.
>
> Best regards,
> Krzysztof
>
Best regards
Mårten
>
> > +
> > + writel(i2c_addr, i2c->regs + HSI2C_ADDR);
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next prev parent reply other threads:[~2021-02-16 22:10 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
2021-02-16 22:09 ` Marten Lindahl [this message]
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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