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Subject: Re: [PATCH 4/5] clk: qcom: Add camera clock controller driver for SM8150
From: Stephen Boyd <sboyd@kernel.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>, linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Ajit Pandey <quic_ajipan@quicinc.com>, Imran Shaik <quic_imrashai@quicinc.com>, Taniya Das <quic_tdas@quicinc.com>, Jagadeesh Kona <quic_jkona@quicinc.com>
To: Abhishek Sahu <absahu@codeaurora.org>, Bjorn Andersson <andersson@kernel.org>, Bryan O'Donoghue <bryan.odonoghue@linaro.org>, Conor Dooley <conor+dt@kernel.org>, Konrad Dybcio <konrad.dybcio@linaro.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Michael Turquette <mturquette@baylibre.com>, Rob Herring <robh@kernel.org>, Satya Priya Kakitapalli (Temp) <quic_skakitap@quicinc.com>
Date: Fri, 05 Apr 2024 14:32:10 -0700
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Quoting Satya Priya Kakitapalli (Temp) (2024-04-04 23:27:29)
>=20
> On 3/2/2024 9:43 PM, Bryan O'Donoghue wrote:
> >
> > Alternatively switch on the always-on clocks before the really_probe() =

> > but then roll back in a probe_err: goto
> >
> > probe_err:
> > =C2=A0=C2=A0=C2=A0=C2=A0remap_bits_update(regmap, 0xc1e4, BIT(0), 0);
> > =C2=A0=C2=A0=C2=A0=C2=A0pm_runtime_put_sync(&pdev->dev);
> >
> > There may be corner cases where always-on has to happen before=20
> > really_probe() I suppose but as a general pattern the above should be=20
> > how we go.
> >
>=20
> I have rechecked this and see that this clock is PoR ON (i.e BIT(0) is=20
> set upon power ON) and it should be kept always ON as per HW=20
> recommendation. So even if the probe fails we shouldn't be clearing it=20
> against the hw recommendation. We are setting the bit here again to make =

> sure it is set when the driver probes.
>=20

Yes, always on clks should always be on. We don't turn them off if the
driver fails to probe. We should probably print a warning or something
if the register write fails, but since this is mmio it won't fail, so
just make sure they're on and move on.