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[69.109.179.158]) by smtp.gmail.com with ESMTPSA id cg9-20020a05690c0a0900b00545a08184b8sm2794019ywb.72.2023.04.03.15.20.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Apr 2023 15:20:58 -0700 (PDT) Date: Mon, 3 Apr 2023 18:20:56 -0400 From: William Breathitt Gray To: Mark Brown Cc: Andy Shevchenko , Linus Walleij , Bartosz Golaszewski , linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, techsupport@winsystems.com, Paul Demetrotion , Michael Walle Subject: Re: [PATCH v5 3/3] gpio: ws16c48: Migrate to the regmap API Message-ID: References: <58531b1b2428e4d5d2ea79e721f7ef6450665280.1679845842.git.william.gray@linaro.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="50JiiM9KWQUDRx4Z" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org --50JiiM9KWQUDRx4Z Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 03, 2023 at 10:12:44PM +0100, Mark Brown wrote: > On Sun, Apr 02, 2023 at 10:39:02AM -0400, William Breathitt Gray wrote: > > On Mon, Mar 27, 2023 at 02:26:37PM +0300, Andy Shevchenko wrote: > > > On Sun, Mar 26, 2023 at 12:25:59PM -0400, William Breathitt Gray wrot= e: >=20 > > > > +static const struct regmap_config ws16c48_regmap_config =3D { > > > > + .reg_bits =3D 8, > > > > + .reg_stride =3D 1, > > > > + .val_bits =3D 8, > > > > + .io_port =3D true, > > > > + .max_register =3D 0xA, > > > > + .wr_table =3D &ws16c48_wr_table, > > > > + .rd_table =3D &ws16c48_rd_table, > > > > + .volatile_table =3D &ws16c48_volatile_table, > > > > + .cache_type =3D REGCACHE_FLAT, > > > > +}; >=20 > > > Do we need regmap lock? >=20 > > We make regmap calls within an interrupt context in this driver so I > > think we need to disable the default regmap mutex locking behavior; I > > believe the current raw_spin_lock locking in this driver is enough to > > protect access. >=20 > The above doesn't configure the regmap locking so you'll have a spinlock > by default (MMIO being a fast bus). You're right, it'll be a spinlock in this case and not mutex. Unfortunately, we'll still need to change that to avoid deadlocks on -rt kernels [0]. William Breathitt Gray [0] https://lore.kernel.org/all/1466065537-82027-1-git-send-email-mika.west= erberg@linux.intel.com/ --50JiiM9KWQUDRx4Z Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQSNN83d4NIlKPjon7a1SFbKvhIjKwUCZCtRSAAKCRC1SFbKvhIj Ky0DAP9IpyENdB034mfM5YZYx5/meDB6ZINnU28U/PqlovWaAAD9Hf4p7mhg2j/v Wxu906U2SCA8gH1bxrcyur4P5T0EHgY= =fMtc -----END PGP SIGNATURE----- --50JiiM9KWQUDRx4Z--