Re: [PATCH 1/2 v3] i2c: exynos5: add support for HSI2C on Exynos5260SoC

[Tomasz Figa]

Also, please use correct addresses of DT ML and Wolfram's e-mail (fixed 
in this message).

Best regards,
Tomasz

On 06.02.2014 14:31, Tomasz Figa wrote:
> Hi Naveen,
>
> On 06.02.2014 13:06, Naveen Krishna Chatradhi wrote:
> > This patch implements a variant struct to handle the differences
> > (like fifo_depths) in the HSI2C modules across SoCs.
> >
> > Adds a new compatible to support HSI2C module on Exynos5260.
> > Also resets the module as an init sequence (Needed by Exynos5260).
> >
> > Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@xxxxxxxxxxx>
> > ---
> > Changes since v2:
> > 1. Used variant struct as suggested by Tomasz Figa.
> > 2. Change compatible strings from samsung,exynos5-hsi2c to
> >     samsung,exynos5250-hsi2c based on the first SoC to see the feature.
> > 3. Using reset as init sequences.
> > 4. Merged the 2 patches into one.
> >
> >   .../devicetree/bindings/i2c/i2c-exynos5.txt        |    8 ++-
> >   drivers/i2c/busses/i2c-exynos5.c                   |   64
> > ++++++++++++++++----
> >   2 files changed, 58 insertions(+), 14 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> > b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> > index 056732c..5bc4998 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> > @@ -5,7 +5,11 @@ at various speeds ranging from 100khz to 3.4Mhz.
> >
> >   Required properties:
> >     - compatible: value should be.
> > -      -> "samsung,exynos5-hsi2c", for i2c compatible with exynos5 hsi2c.
>
> Device tree bindings need to be backwards compatible, so you need to
> keep this compatible string supported, just marked as (DEPRECATED).
>
> Driver-wise, it will use the same driver data / variant struct as
> "samsung,exynos5250-hsi2c", just one more entry in OF match table is
> needed.
>
> > +    -> "samsung,exynos5250-hsi2c", for i2c compatible with HSI2C
> > available
> > +                on Exynos5250 and Exynos5420 SoCs.
> > +    -> "samsung,exynos5260-hsi2c", for i2c compatible with HSI2C
> > available
> > +                on Exynos5260 SoCs.
> > +
> >     - reg: physical base address of the controller and length of
> > memory mapped
> >       region.
> >     - interrupts: interrupt number to the cpu.
> > @@ -26,7 +30,7 @@ Optional properties:
> >   Example:
> >
> >   hsi2c@12ca0000 {
> > -    compatible = "samsung,exynos5-hsi2c";
> > +    compatible = "samsung,exynos5250-hsi2c";
> >       reg = <0x12ca0000 0x100>;
> >       interrupts = <56>;
> >       clock-frequency = <100000>;
>
> [snip]
>
> > @@ -483,6 +514,7 @@ static void exynos5_i2c_message_start(struct
> > exynos5_i2c *i2c, int stop)
> >       u32 i2c_auto_conf = 0;
> >       u32 fifo_ctl;
> >       unsigned long flags;
> > +    unsigned short trig_lvl;
> >
> >       i2c_ctl = readl(i2c->regs + HSI2C_CTL);
> >       i2c_ctl &= ~(HSI2C_TXCHON | HSI2C_RXCHON);
> > @@ -493,13 +525,19 @@ static void exynos5_i2c_message_start(struct
> > exynos5_i2c *i2c, int stop)
> >
> >           i2c_auto_conf = HSI2C_READ_WRITE;
> >
> > -        fifo_ctl |= HSI2C_RXFIFO_TRIGGER_LEVEL(HSI2C_DEF_TXFIFO_LVL);
> > +        trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
> > +            (i2c->variant->fifo_depth * 3/4) : i2c->msg->len;
> > +        fifo_ctl |= HSI2C_RXFIFO_TRIGGER_LEVEL(trig_lvl);
> > +
>
> This is a rather serious semantic change, that doesn't look to belong to
> this patch. If this is needed, it should be done in a separate patch.
>
> >           int_en |= (HSI2C_INT_RX_ALMOSTFULL_EN |
> >               HSI2C_INT_TRAILING_EN);
> >       } else {
> >           i2c_ctl |= HSI2C_TXCHON;
> >
> > -        fifo_ctl |= HSI2C_TXFIFO_TRIGGER_LEVEL(HSI2C_DEF_RXFIFO_LVL);
> > +        trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
> > +            (i2c->variant->fifo_depth * 1/4) : i2c->msg->len;
> > +        fifo_ctl |= HSI2C_TXFIFO_TRIGGER_LEVEL(trig_lvl);
> > +
>
> Ditto.
>
> Best regards,
> Tomasz
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