Messages in this thread | | | Subject | Re: [PATCH] ACPI / LPSS: Do not instiate a platform_dev for devs without a mmio resource | From | Hans de Goede <> | Date | Mon, 15 Jan 2018 09:42:48 +0100 |
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Hi,
On 15-01-18 00:36, Rafael J. Wysocki wrote: > On Sun, Jan 14, 2018 at 9:01 PM, Hans de Goede <hdegoede@redhat.com> wrote: >> acpi_lpss_create_device() skips handling LPSS devices which do not have >> a mmio resources in their resource list (typically these devices are >> disabled by the firmware). But since the LPSS code does not bind to the >> device, acpi_bus_attach() ends up still creating a platform device for >> it and the regular platform_driver for the ACPI HID still tries to bind >> to it. >> >> This happens e.g. on some boards which do not use the pwm-controller >> and have an empty or invalid resource-table for it. Currently this causes >> these error messages to get logged: >> [ 3.281966] pwm-lpss 80862288:00: invalid resource >> [ 3.287098] pwm-lpss: probe of 80862288:00 failed with error -22 >> >> This commit stops the undesirable creation of a platform_device for >> disabled LPSS devices by setting pnp.type.platform_id to 0. Note that >> acpi_scan_attach_handler() also sets pnp.type.platform_id to 0 when there >> is a matching handler for the device and that handler has no attach >> callback, so we simply behave as a handler without an attach function >> in this case. >> >> Signed-off-by: Hans de Goede <hdegoede@redhat.com> > > Does this fix new behavior or is it an old issue?
The problem this addresses is likely caused by the acpi_always_present entry for the CHT 80862288 PWM devices in drivers/acpi/x86/utils.c.
The problem is that under Windows the Intel GPU driver has hardcoded addresses for the PWM LPSS bits (or so I believe), rather then having it as a separate device with a separate driver, so the CHT LPSS PWM device's _STA returns 0 on all x86 devices which ship with Windows.
On most CHT laptops / tablets it is used to control the backlight brightness so we do need the device under Linux, where we've a separate PWM driver and we don't want to be hardcoding stuff like this.
So we really cannot do without the acpi_always_present entry, and thus need this extra check for devices where the pwm is actually unused and disabled by the firmware.
Regards,
Hans
>> --- >> drivers/acpi/acpi_lpss.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c >> index 9cfe6b71078b..166a8e582d96 100644 >> --- a/drivers/acpi/acpi_lpss.c >> +++ b/drivers/acpi/acpi_lpss.c >> @@ -610,6 +610,8 @@ static int acpi_lpss_create_device(struct acpi_device *adev, >> acpi_dev_free_resource_list(&resource_list); >> >> if (!pdata->mmio_base) { >> + /* Avoid acpi_bus_attach() instantiating a pdev for this dev. */ >> + adev->pnp.type.platform_id = 0; >> /* Skip the device, but continue the namespace scan. */ >> ret = 0; >> goto err_out; >> -- >> 2.14.3 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html
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