Thread (102 messages) 102 messages, 22 authors, 2015-10-27

Re: [GIT PULL] On-demand device probing

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: 2015-10-21 08:55:28
Also in: dri-devel, linux-clk, linux-fbdev, linux-gpio, linux-i2c, linux-pm, linux-pwm, linux-tegra, lkml

Hi Rafael,

On Wed, Oct 21, 2015 at 1:34 AM, Rafael J. Wysocki [off-list ref] wrote:
On Tuesday, October 20, 2015 09:15:01 AM Rob Herring wrote:
quoted
On Tue, Oct 20, 2015 at 2:56 AM, Rafael J. Wysocki [off-list ref] wrote:
quoted
ACPI uses platform devices too.  In fact, ACPI device objects are enumerated as
platform devices by default now.
Okay, I should have grepped for that:
drivers/base/platform.c:                ACPI_COMPANION_SET(&pdev->dev, NULL);
drivers/base/platform.c:        len = acpi_device_modalias(dev, buf,
PAGE_SIZE -1);
drivers/base/platform.c:        rc = acpi_device_uevent_modalias(dev, env);
drivers/base/platform.c:        /* Then try ACPI style match */
drivers/base/platform.c:        if (acpi_driver_match_device(dev, drv))

These are all cases which have DT version as well, so we're not really
all that different here. There's a few more for DT, but that probably
means you have just not hit the problems we have yet. For example,
what happens if you have an interrupt line in which the controller is
probed after the device connected to the interrupt line? That required
resolving irqs in platform_get_irq rather than using static resources
to support deferred probe.
We don't have this particular problem, because the IRQ controllers are
enumerated in a special way.
What does "in a special way" mean? Can you please be more specific?

Can you have interrupt controllers that depend on clocks, pin controllers,
and PM domains?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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