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    SubjectRe: [rtc-linux] [PATCH 8/8] ARM: vt8500: gpio: Devicetree support for arch-vt8500
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    On Wednesday 08 August 2012, Linus Walleij wrote:
    > On Wed, Aug 8, 2012 at 3:39 AM, Tony Prisk <linux@prisktech.co.nz> wrote:
    >
    > > Converted the existing arch-vt8500 gpio to a platform_device.
    > > Added support for WM8505 and WM8650 GPIO controllers.
    > (...)
    > > +++ b/drivers/gpio/gpio-vt8500.c
    >
    > This driver looks very one-bit-per-gpio typed. Are you sure you cannot
    > just reuse drivers/gpio/gpio-generic.c? Make a compelling case please...
    >
    > > +struct vt8500_gpio_bank_regs {
    > > + int en;
    > > + int dir;
    > > + int data_out;
    > > + int data_in;
    >
    > Why are all these members int? They should be u8 from reading your code.
    >
    > > + int ngpio;
    > > +};

    Not necessarily 8 bit, but definitely unsigned.

    > > +static struct vt8500_gpio_data vt8500_data = {
    > > + .num_banks = 7,
    > > + .banks = {
    > > + VT8500_BANK(0x00, 0x20, 0x40, 0x60, 26),
    > > + VT8500_BANK(0x04, 0x24, 0x44, 0x64, 28),
    > > + VT8500_BANK(0x08, 0x28, 0x48, 0x68, 31),
    > > + VT8500_BANK(0x0C, 0x2C, 0x4C, 0x6C, 19),
    > > + VT8500_BANK(0x10, 0x30, 0x50, 0x70, 19),
    > > + VT8500_BANK(0x14, 0x34, 0x54, 0x74, 23),
    > > + VT8500_BANK(-1, 0x3C, 0x5C, 0x7C, 9), /* external gpio */
    >
    > What on earth are all those magic numbers?
    >
    > I *guess* they're enabling some default GPIO settings etc.

    No, they are the register offsets you quoted above, per bank. There
    is no easy way to abstract these, and I suggested putting the
    values into the source code rather than describing each bank
    separately in the .dtsi file.

    My feeling however is that the "vt8500_chip->regoff" is wrong, which
    would mean only the first bank works. The code adds the same offsets
    per bank once more that it sets in this bank table.

    Arnd


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