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List:       linux-tegra
Subject:    Re: [PATCH V2 01/11] soc/tegra: pmc: Initialise resets associated with a power partition
From:       Thierry Reding <thierry.reding () gmail ! com>
Date:       2016-06-30 9:49:02
Message-ID: 20160630094902.GD1776 () ulmo ! ba ! sec
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On Wed, Jun 29, 2016 at 10:17:47AM +0100, Jon Hunter wrote:
> When registering the Tegra power partitions with the generic PM domain
> framework, the current state of the each partition is checked and used
> as the default state for the partition. However, the state of each reset
> associated with the partition is not initialised and so it is possible
> that the state of the resets are not in the expected state. For example,
> if a partition is on, then the resets should be de-asserted and if the
> partition is off, the resets should be asserted.
> 
> There have been cases where the bootloader has powered on a partition
> and only de-asserted some of the resets to some of the devices in the
> partition. This can cause accesses to these devices to hang the system
> when the kernel boots and attempts to probe these devices.
> 
> Ideally, the driver for the device should ensure the reset has been
> de-asserted when probing, but the resets cannot be shared between the
> PMC driver (that needs to de-assert/assert the reset when turning the
> partition on or off) and another driver because we cannot ensure the
> reset is in the correct state.
> 
> To ensure the resets are in the correct state, when using the generic
> PM domain framework, put each reset associated with the partition in
> the correct state (based upon the partition's current state) when
> obtaining the resets for a partition.
> 
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
> ---
>  drivers/soc/tegra/pmc.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)

Applied to for-4.8/soc, thanks.

Thierry

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