Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 21 Jun 2022 14:37:35 +0100
From:   John Keeping <john@metanate.com>
To:     LABBE Corentin <clabbe@baylibre.com>
Cc:     heiko@sntech.de, ardb@kernel.org, herbert@gondor.apana.org.au,
        krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v7 14/33] crypto: rockchip: handle reset also in PM
Message-ID: <YrHJn6Pl5B/1pj9L@donbot>
References: <20220508185957.3629088-1-clabbe@baylibre.com>
 <20220508185957.3629088-15-clabbe@baylibre.com>
 <YrBUODGF51oUsF1f@donbot>
 <YrF74tmA9qc+I3JF@Red>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <YrF74tmA9qc+I3JF@Red>
Precedence: bulk

On Tue, Jun 21, 2022 at 10:05:54AM +0200, LABBE Corentin wrote:
> Le Mon, Jun 20, 2022 at 12:04:24PM +0100, John Keeping a ?crit :
> > On Sun, May 08, 2022 at 06:59:38PM +0000, Corentin Labbe wrote:
> > > reset could be handled by PM functions.
> > 
> > Is there any further rationale for this?
> > 
> > After this change there is no longer a guaranteed reset pulse on probe
> > since the reset control may already be de-asserted.  This is normally
> > the most important case for a reset as it's the only time when the state
> > of the hardware is unknown.
> > 
> > The original use of devm_add_action_or_reset() seems a bit weird already
> > since there doesn't seem to be any need to assert reset when the driver
> > is unloaded.
> > 
> 
> I am not an hw engineer, so my knowledge on reset is low.
> So why not having a reset pulse on probe is a problem ?

The point of the reset is to bring the hardware back to a known state.
Since we don't know what state the hardware will be in following the
bootloader or previous OS, I think the reset in probe is the only place
that it is important.

If this patch isn't fixing anything, I suggest just dropping it.