plat-orion multi purpose pins problem for mv78200

[saeed.bishara@gmail.com (saeed bishara)]

On Wed, Jul 6, 2011 at 9:49 PM, Joey Oravec <joravec@drewtech.com> wrote:
> On 7/6/2011 12:18 PM, Simon Guinot wrote:
>>>
>>> Note that orion_gpio_set_valid() and orion_gpio_is_valid() would
>>> both need rework. The functions need to handle that a GPIO can be
>>> mux'ed onto any MPP pin. I described this problem in another email
>>> on the thread.
>>
>> I don't understand what's wrong with the GPIO array.
>
> I tried to describe the case in my reply:
> http://lists.arm.linux.org.uk/lurker/message/20110701.215657.7efe0a42.en.html
>
> Assume that we've solved the mpp_to_gpio mapping. Then imagine you pass a
> large array to mv78xx0_mpp_conf() that includes:
>
> MPP16_GPIO (this mpp corresponds to GPIO16)
> MPP47_UNUSED (this mpp corresponds to GPIO16)
>
> The code today processes the array in-order. When it processes MPP16_GPIO it
> will mark the GPIO16 valid. When it processes MPP47_UNUSED it would
> currently mark GPIO16 invalid. This is a problem because it still assumes a
> 1:1 relationship.
I agree, this is why we need some method to make the orion_mpp_conf()
know which mpps are gpios, when that done, then the gpio of MPP47 in
your case will not be set as invalid.
one option to do that is to assume that mpp with _in == out_ == 0 is
not a gpio. so the orion_mpp_conf() will look like this:
--- a/arch/arm/plat-orion/mpp.c
+++ b/arch/arm/plat-orion/mpp.c
@@ -41,6 +41,7 @@ void __init orion_mpp_conf(unsigned int *mpp_list,
unsigned int variant_mask,
        for ( ; *mpp_list; mpp_list++) {
                unsigned int num = MPP_NUM(*mpp_list);
                unsigned int sel = MPP_SEL(*mpp_list);
+               unsigned int gpio_num = MPP_GPIO(*mpp_list);
                int shift, gpio_mode;

                if (num > mpp_max) {
@@ -64,9 +65,8 @@ void __init orion_mpp_conf(unsigned int *mpp_list,
unsigned int variant_mask,
                        gpio_mode |= GPIO_INPUT_OK;
                if (*mpp_list & MPP_OUTPUT_MASK)
                        gpio_mode |= GPIO_OUTPUT_OK;
-               if (sel != 0)
-                       gpio_mode = 0;
-               orion_gpio_set_valid(num, gpio_mode);
+               if (gpio_mode != 0)
+                       orion_gpio_set_valid(gpio_num, gpio_mode);
        }


and of course this will require that any non gpio mpp will have to
have the _in and _out set to 0.
saeed