Received-SPF: pass (google.com: domain of linux-kernel+bounces-80300-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Sun, 25 Feb 2024 22:10:30 +0100
From: Sebastian Reichel <sebastian.reichel@collabora.com>
To: Hermes Zhang <chenhuiz@axis.com>
Cc: Hermes Zhang <Hermes.Zhang@axis.com>, kernel@axis.com, 
	Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] power: supply: bq27xxx: Introduce parameter to config
 cache regs
Message-ID: <op5ovg3cv4raqy4zmol7wfy7hm72ptgxleh2ykoyg5qvnbhfcl@pxfzkij5xkkw>
References: <20240219100541.48453-1-Hermes.Zhang@axis.com>
 <eh34cvorgnrw4v5a6emzjk2p6om2ybkn627bpmh775z4ubw63h@nbxgpm767u4x>
 <1fe2c4b3-9dd2-a961-4198-45aca3449c36@axis.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="aqiglmpeyh36bxal"
Content-Disposition: inline
In-Reply-To: <1fe2c4b3-9dd2-a961-4198-45aca3449c36@axis.com>


--aqiglmpeyh36bxal
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

Hi,

On Fri, Feb 23, 2024 at 04:40:18PM +0800, Hermes Zhang wrote:
> On 2024/2/22 7:03, Sebastian Reichel wrote:
> > On Mon, Feb 19, 2024 at 06:05:40PM +0800, Hermes Zhang wrote:
> > > Since all of the regs in the bq27xxx_reg_cache are now cached, a simp=
le
> > > property read (such as temperature) will need nine I2C transmissions.
> > > Introduce a new module parameter to enable the reg cache to be config=
ured,
> > > which decrease the amount of unnecessary I2C transmission and prevent=
ing
> > > the error -16 (EBUSY) happen when working on an I2C bus that is share=
d by
> > > many devices.
> > So the problem is not the caching, but the grouping. So instead
> > of adding this hack, please change the code to do the caching
> > per register. That way you can just keep the caching enabled and
> > don't need any custom module parameters.
>=20
> Thanks for the reply. Yes, the key is the grouping. So do you suggest to
> drop the bq27xxx_reg_cache struct totally and handle the cache for each
> register in e.g. bq27xxx_battery_get_property()? Then it will require an
> extra time info for each register, will that be a big cost? Or am I
> misunderstanding?

Yes, this requires time info for each cached register. I don't think
the added memory is a big deal. There usually is only a single
battery and we are caching 10 timestamps. So that's 80 bytes.

-- Sebastian

--aqiglmpeyh36bxal
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=e0sY
-----END PGP SIGNATURE-----

--aqiglmpeyh36bxal--