[PATCH 0/9] ARM: sa1100: Rework IRQ handling
Dmitry Eremin-Solenikov
dbaryshkov at gmail.com
Tue Nov 19 10:17:46 EST 2013
On 11/19/2013 05:00 PM, Linus Walleij wrote:
> On Fri, Nov 15, 2013 at 9:47 AM, Dmitry Eremin-Solenikov
> <dbaryshkov at gmail.com> wrote:
>
>> 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
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