From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Hans Verkuil <hverkuil@xs4all.nl>,
linux-media@vger.kernel.org, linux-tegra@vger.kernel.org,
devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] media: staging: tegra-vde: Power-cycle hardware on probe
Date: Fri, 26 Jun 2020 16:42:35 +0300 [thread overview]
Message-ID: <1c306d0a-571b-dc7c-3a61-0149dfb0e2be@gmail.com> (raw)
In-Reply-To: <20200626074818.GD3109062@ulmo>
26.06.2020 10:48, Thierry Reding пишет:
> On Wed, Jun 24, 2020 at 06:08:47PM +0300, Dmitry Osipenko wrote:
>> VDE partition is left turned ON after bootloader on most devices, hence
>> let's ensure that it's turned OFF in order to lower power leakage while
>> hardware is idling by turning it ON and OFF during of the driver's probe.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>> drivers/staging/media/tegra-vde/vde.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/staging/media/tegra-vde/vde.c b/drivers/staging/media/tegra-vde/vde.c
>> index b64e35b86fb4..3be96c36bf43 100644
>> --- a/drivers/staging/media/tegra-vde/vde.c
>> +++ b/drivers/staging/media/tegra-vde/vde.c
>> @@ -1068,6 +1068,14 @@ static int tegra_vde_probe(struct platform_device *pdev)
>> pm_runtime_use_autosuspend(dev);
>> pm_runtime_set_autosuspend_delay(dev, 300);
>>
>> + /*
>> + * VDE partition may be left ON after bootloader, hence let's
>> + * power-cycle it in order to put hardware into a predictable lower
>> + * power state.
>> + */
>> + pm_runtime_get_sync(dev);
>> + pm_runtime_put(dev);
>> +
>> return 0;
>>
>> err_deinit_iommu:
>
> Shouldn't this happen automatically? My understanding is that power
> domains are turned on automatically before ->probe() and then unless a
> runtime PM reference is taken during ->probe() it will get turned off
> again after ->probe()?
Older Tegra SoCs haven't been converted to use the generic power-domain
API and today's VDE driver supports only T20 and T30 SoCs.
> Is that not happening? Is auto-suspend perhaps getting in the way
> somehow?
We're manually toggling the PD using legacy Tegra-PD API in the driver's
RPM callbacks, that's why the RPM needs to be toggled manually as well.
Perhaps this hunk could be removed if older Tergas would get a genpd
support. I guess it shouldn't be difficult to implement the genpd
support, but then there will be a compatibility trouble with older DTs,
so perhaps it's not really worth the effort.
next prev parent reply other threads:[~2020-06-26 13:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 15:08 [PATCH v2 0/4] Tegra Video Decoder driver power management corrections Dmitry Osipenko
2020-06-24 15:08 ` [PATCH v2 1/4] media: staging: tegra-vde: Balance runtime PM use-count on resume failure Dmitry Osipenko
2020-06-24 15:08 ` [PATCH v2 2/4] media: staging: tegra-vde: Runtime PM is always available on Tegra Dmitry Osipenko
2020-06-26 7:44 ` Thierry Reding
2020-06-24 15:08 ` [PATCH v2 3/4] media: staging: tegra-vde: Turn ON power domain on shutdown Dmitry Osipenko
2020-06-26 7:43 ` Thierry Reding
2020-06-24 15:08 ` [PATCH v2 4/4] media: staging: tegra-vde: Power-cycle hardware on probe Dmitry Osipenko
2020-06-26 7:48 ` Thierry Reding
2020-06-26 13:42 ` Dmitry Osipenko [this message]
2020-06-24 15:16 ` [PATCH v2 0/4] Tegra Video Decoder driver power management corrections Hans Verkuil
2020-06-24 15:23 ` Dmitry Osipenko
2020-06-26 0:17 ` Dmitry Osipenko
2020-06-26 6:58 ` Hans Verkuil
2020-06-26 13:23 ` Dmitry Osipenko
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