From: Stephen Boyd <sboyd@kernel.org>
To: Amit Nischal <anischal@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Michael Turquette <mturquette@baylibre.com>,
Taniya Das <tdas@codeaurora.org>
Cc: dmitry.baryshkov@linaro.org, linux-arm-msm@vger.kernel.org,
linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] clk: qcom: rcg2: Cache CFG register updates for parked RCGs
Date: Mon, 04 Apr 2022 13:16:49 -0700 [thread overview]
Message-ID: <20220404201651.0B3A2C2BBE4@smtp.kernel.org> (raw)
In-Reply-To: <20220308040348.1340405-1-bjorn.andersson@linaro.org>
Quoting Bjorn Andersson (2022-03-07 20:03:48)
> As GDSCs are turned on and off some associated clocks are momentarily
> enabled for house keeping purposes. For this, and similar, purposes the
> "shared RCGs" will park the RCG on a source clock which is known to be
> available.
> When the RCG is parked, a safe clock source will be selected and
> committed, then the original source would be written back and upon enable
> the change back to the unparked source would be committed.
>
> But starting with SM8350 this fails, as the value in CFG is committed by
> the GDSC handshake and without a valid parent the GDSC enablement will
> fail.
>
> To avoid this problem, the software needs to cache the CFG register
> content while the shared RCG is parked.
>
> Writes to M, N and D registers are committed as they are requested. New
> helpers for get_parent() and recalc_rate() are extracted from their
> previous implementations and __clk_rcg2_configure() is modified to allow
> it to operate on the cached value.
>
> Fixes: 7ef6f11887bd ("clk: qcom: Configure the RCGs to a safe source as needed")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
Sorry I've been delaying reviewing this patch. I'll review it in the
next couple days.
next prev parent reply other threads:[~2022-04-04 21:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-08 4:03 [PATCH v2] clk: qcom: rcg2: Cache CFG register updates for parked RCGs Bjorn Andersson
2022-04-04 20:16 ` Stephen Boyd [this message]
2022-04-12 18:56 ` Stephen Boyd
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