On Thursday, January 15, 2015 01:10:44 PM Andy Shevchenko wrote:
> We can't rely on the first enumerated device since it might be not probed yet
> when DMA driver wants to resume the device. This patch changes the place where
> we assign the 'proxy' device. From now on the first resumed device will be
> recognized as a 'proxy' because it is probed.
I was about to apply this, but I realized that we couldn't do it this way. ->
> Reported-by: Jerome Blin <jerome.blin@xxxxxxxxx>
> Fixes: 6c17ee44d524 (ACPI / LPSS: introduce a 'proxy' device to power on LPSS for DMA)
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> drivers/acpi/acpi_lpss.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
> index 4f3febf..d851290 100644
> --- a/drivers/acpi/acpi_lpss.c
> +++ b/drivers/acpi/acpi_lpss.c
> @@ -374,8 +374,6 @@ static int acpi_lpss_create_device(struct acpi_device *adev,
> adev->driver_data = pdata;
> pdev = acpi_create_platform_device(adev);
> if (!IS_ERR_OR_NULL(pdev)) {
> - if (!proxy_device && dev_desc->flags & LPSS_DEV_PROXY)
> - proxy_device = &pdev->dev;
> return 1;
> }
>
> @@ -615,10 +613,17 @@ static int acpi_lpss_runtime_resume(struct device *dev)
> struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
> int ret;
>
> - if (pdata->dev_desc->flags & LPSS_PROXY_REQ && proxy_device) {
> - ret = pm_runtime_get_sync(proxy_device);
> - if (ret)
> - return ret;
> + if (!proxy_device && pdata->dev_desc->flags & LPSS_DEV_PROXY)
> + proxy_device = dev;
-> OK, so what if the driver of proxy_device is removed later?
> +
> + if (pdata->dev_desc->flags & LPSS_PROXY_REQ) {
> + if (proxy_device) {
> + ret = pm_runtime_get_sync(proxy_device);
> + if (ret)
> + return ret;
> + } else {
> + return -EPROBE_DEFER;
The error code returned here will disable runtime PM for dev forever,
even if proxy_device becomes available at one point. You could return
-EBUSY instead, but why don't we add BUS_NOTIFY_BOUND_DRIVER and
BUS_NOTIFY_UNBIND_DRIVER handling to acpi_lpss_platform_notify() and
set/unset proxy_device from there?
> + }
> }
>
> ret = acpi_dev_runtime_resume(dev);
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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