[U-Boot] [PATCH] arch-mx6: fix MX6_PAD_DECLARE macro to work with MX6 duallite

[Stefano Babic <sbabic@denx.de>]

Hi Hannes,

On 21/07/2016 08:10, Hannes Schmelzer wrote:

> Just looked around a bit more about this.
> Root cause for failing this patch is, that many boards do not use the
> 'IOMUX_PADS' macro, instead they just directly use the definition out of
> "mx6dl_pins.h" for example.

Both are allowed. IOMUX_PADS *must* be used in case the board supports
multiple variant of the processor (DL, Quad,..). If the board has just
one variant, the MX6 defines from the corresponding header can be used.

> So we get in trouble there if we change the MX6_PAD_DECLARE macro for
> having MX6DL pads instead MX6 pads.

I am not getting where is the trouble, because there are already a lot
of boards using it. Let's see....

> 
> At one point of view it would make sense to me changing all boards to
> use the IOMUX_PADS macro for accessing pads register, because afterwards
> the real accessed register would be fully in dependence of CONFIG_MX6nn.
> On the other hand i cannot fully predict every case could happen if we
> simply change that with search/replace.
> 
> So it would be OK for me to drop this patch and i will use on my board:
> 
> MX6DL_PAD_ENET_TX_EN__I2C4_SCL
> MX6DL_PAD_ENET_TXD1__I2C4_SDA
> 

Now I get the point - and yes, there is an exception for I2C in the
pinmux. This was discussed at the beginning when IOMUX_PADS was
introduced and how to support the different layout of the SOC variants.

We agreed to tread differently I2C. This means that a i2c_pads_info
structure must be set for each variant of the SOC that board supports.
With help of the is_cpu_type() macro (or one of this family), the
correct structure is selected and the pinmux can be set.

The right way to do is:


static struct i2c_pads_info i2c_pad = {
        .scl = {
                .i2c_mode = MX6DL_PAD_ENET_TX_EN__I2C4_SCL | <pull up>,
                .gpio_mode = MX6DL_PAD_ENET_TX_EN__GPIO1_IO28 | <..>,
                .gp = IMX_GPIO_NR(1, 28)
        },
        .sda = {
                .i2c_mode = MX6DL_PAD_ENET_TXD1__I2C4_SDA | <pull >,
                .gpio_mode = MX6DL_PAD_ENET_TXD1__GPIO1_IO29 | <pull>,
                .gp = IMX_GPIO_NR(1, 29)
        }
};


and then you call setup_i2c() with the structure.

Best regards,
Stefano Babic

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