[PATCH 0/9] ARM: sa1100: Rework IRQ handling

On 11/19/2013 05:00 PM, Linus Walleij wrote:

On Fri, Nov 15, 2013 at 9:47 AM, Dmitry Eremin-Solenikov
[off-list ref] wrote:

quoted

This is a considerable rework of my previous attempt to update sa1100 irq
handling. IRQ code is updated to support MULTI_IRQ_HANDLER and is mostly
prepared to be converted to irqchip driver (if the need arises in future).
I have integrated idea of Linus Waleij to use irq domains. GPIO irq handling
is split to gpio driver, which also undergo an update/rewrite.

Overall this is looking very nice. However when I apply this on top
of (a working and booting) mainline HEAD, I get this:

[skipped]

This is caused by the patch:
"ARM: sa1100: convert gpio driver to be a proper platform driver"

The reason: UARTs are initialized *very* early and the UART quirk used on the
h3600 is using GPIOs through the .set_mctrl hooks back into
arch/arm/mach-sa1100/h3xxx.c functions
h3xxx_uart_set_mctrl()
h3xxx_uart_get_mctrl()

And that happens before the GPIO driver gets registered -> crash.

That is not the issue. The real issue is h3xxx using those gpio's 
without previously calling gpio_request. Unfortunately sa1100 driver 
doesn't have a good place to request gpios. When faced this problem 
during locomo refactoring, I ended up with the following piece of code:

========== Cut here ============
static struct gpio collie_uart_gpio[] = {
         { COLLIE_GPIO_CTS, GPIOF_IN, "CTS" },
         { COLLIE_GPIO_RTS, GPIOF_OUT_INIT_LOW, "RTS" },
         { COLLIE_GPIO_DTR, GPIOF_OUT_INIT_LOW, "DTR" },
         { COLLIE_GPIO_DSR, GPIOF_IN, "DSR" },
};

static bool collie_uart_gpio_ok;

static void collie_uart_set_mctrl(struct uart_port *port, u_int mctrl)
{
         if (!collie_uart_gpio_ok) {
                 int rc = gpio_request_array(collie_uart_gpio,
                                 ARRAY_SIZE(collie_uart_gpio));
                 if (rc)
                         printk("collie_uart_set_mctrl: gpio request 
%d\n", rc);
                 else
                         collie_uart_gpio_ok = true;
         }

         if (collie_uart_gpio_ok) {
                 gpio_set_value(COLLIE_GPIO_RTS, !(mctrl & TIOCM_RTS));
                 gpio_set_value(COLLIE_GPIO_DTR, !(mctrl & TIOCM_DTR));
         }
}
=========== Cut here ===============

Same goes for get_mctr().

Russell, Linus, what do you think about the previous solution?


Another solution would be to make sa1100 distinguish between console 
output (where it doesn't have to control rts/dtr) and normal uart work 
(where 'modem' lines should be used).

I have the feeling that sa11x0-serial driver would need to be somewhat 
modified at least. I understand the conception behind unified 
"port_fns", but I think that those should be split to a per-port 
platform data.

This is why the device is registered from the machine in the first place
I think.

I don't know what the proper solution is, but I think you can keep most
of the platform device conversion if you also keep the special initialization
call.

That would be possible solution if we can't come up with usefull way to 
handle h3xxx (and collie) gpios.

-- 
With best wishes
Dmitry