From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH 2/2] pinctrl: sunxi: Fix and simplify pin bank regulator handling Date: Thu, 10 Jan 2019 16:28:51 +0100 Message-ID: <20190110152851.g33mgpfgzeatj332@flea> References: <20190110082633.6321-1-wens@csie.org> <20190110082633.6321-2-wens@csie.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2pnopejneh27lbcz" Return-path: Content-Disposition: inline In-Reply-To: <20190110082633.6321-2-wens@csie.org> Sender: linux-kernel-owner@vger.kernel.org To: Chen-Yu Tsai Cc: Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-gpio@vger.kernel.org --2pnopejneh27lbcz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 10, 2019 at 04:26:33PM +0800, Chen-Yu Tsai wrote: > The new per-pin-bank regulator handling code in the sunxi pinctrl driver > has mismatched conditions for enabling and disabling the regulator: it > is enabled each time a pin is requested, but only disabled when the > pin-bank's reference count reaches zero. >=20 > Since we are doing reference counting already, there's no need to enable > the regulator each time a pin is requested. Instead we can just do it > for the first requested pin of each pin-bank. Thus we can reverse the > test and bail out early if it's not the first occurrence. >=20 > Fixes: 9a2a566adb00 ("pinctrl: sunxi: Deal with per-bank regulators") > Signed-off-by: Chen-Yu Tsai Acked-by: Maxime Ripard > I'm getting the feeling that the current code is prone to race > conditions when pinctrl sets are actively switched during runtime, or > gpios are requested and freed from userspace. >=20 > Any ideas? IIRC, I've looked into it when writing that patch and there's an upper mutex that prevents request from being called multiple times at once. Linus might prove me wrong though. Maxime --=20 Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --2pnopejneh27lbcz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCXDdkswAKCRDj7w1vZxhR xT4RAQDm0VrViQOqnAb+y4lxm/C2Kk6e0f9nii3jW/wt7IavcgEA2l2fHktJKyQS bjMr8bur8Y3On3zKYvDRU+a+LHjdEAc= =+NHo -----END PGP SIGNATURE----- --2pnopejneh27lbcz--