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From:   Krishna Yarlagadda <kyarlagadda@nvidia.com>
To:     Mark Brown <broonie@kernel.org>
CC:     "thierry.reding@gmail.com" <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        "linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
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        "p.zabel@pengutronix.de" <p.zabel@pengutronix.de>
Subject: RE: [PATCH v2 4/5] spi: tegra210-quad: add acpi support
Thread-Topic: [PATCH v2 4/5] spi: tegra210-quad: add acpi support
Thread-Index: AQHYKBWa+O2JqvcM5kOPguoIZ3KOyqyf5iWAgADIESCAAliAAIAApvfQ
Date:   Fri, 25 Feb 2022 04:19:49 +0000
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> -----Original Message-----
> From: Mark Brown <broonie@kernel.org>
> Sent: 24 February 2022 23:52
> To: Krishna Yarlagadda <kyarlagadda@nvidia.com>
> Cc: thierry.reding@gmail.com; Jonathan Hunter <jonathanh@nvidia.com>; lin=
ux-spi@vger.kernel.org; linux-tegra@vger.kernel.org;
> Sowjanya Komatineni <skomatineni@nvidia.com>; Laxman Dewangan <ldewangan@=
nvidia.com>; robh+dt@kernel.org;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; p.zabel@pengutr=
onix.de
> Subject: Re: [PATCH v2 4/5] spi: tegra210-quad: add acpi support
>=20
> On Wed, Feb 23, 2022 at 06:32:56AM +0000, Krishna Yarlagadda wrote:
>=20
> > > > +	if (has_acpi_companion(tqspi->dev))
> > > > +		return 0;
> > > >  	/* flush all write which are in PPSB queue by reading back */
> > > >  	tegra_qspi_readl(tqspi, QSPI_COMMAND1);
>=20
> > > As well as clock stuff this is also skipping flushing of pending writ=
es
> > > - is that intentional?  It's not called out in the changelog and seem=
s like
> > > something that could cause issues if someone runs on a system where
> > > the firmware does implement runtime suspend.
>=20
> > Runtime suspend is not enabled with ACPI firmware. Converted compiler f=
lag in v1 to runtime check.
> > We must add more changes like setting DPM flags for runtime pm support =
with ACPI.
> > Can take this as part of a different series.
>=20
> It at least needs to be clearer what's going on here, the changelog
> doesn't match the code and it's not obvious from the code that ACPI
> won't kick in and power manage the device as things stand.
Understood Mark. I will add comments to make it clear.
Also update change log indicating runtime suspend does not work
with ACPI.