From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v1 2/3] clk: tegra: ignore unused vfir clock shared with uartb Date: Wed, 28 Nov 2018 10:24:04 +0100 Message-ID: <20181128092404.GF17419@ulmo> References: <20181101015230.27310-1-marcel@ziswiler.com> <20181101015230.27310-3-marcel@ziswiler.com> <20181101084152.GS7636@tbergstrom-lnx.Nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="924gEkU1VlJlwnwX" Return-path: Content-Disposition: inline In-Reply-To: <20181101084152.GS7636@tbergstrom-lnx.Nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Peter De Schrijver Cc: Marcel Ziswiler , linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, Marcel Ziswiler , Stephen Boyd , Prashant Gaikwad , Jonathan Hunter , Michael Turquette , linux-clk@vger.kernel.org List-Id: linux-tegra@vger.kernel.org --924gEkU1VlJlwnwX Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 01, 2018 at 10:41:52AM +0200, Peter De Schrijver wrote: > On Thu, Nov 01, 2018 at 02:52:29AM +0100, Marcel Ziswiler wrote: > > From: Marcel Ziswiler > >=20 > > As UARTB and VFIR share their clock enable bit it is rather unwise for > > the kernel to turn off the VFIR one should that be unused (and > > potentially vice versa but so far there anyway is no VFIR driver). > >=20 > > Without this patch trying to use UARTB with the regular 8250 driver > > will freeze as soon as ttyS1 is accessed after boot. Luckily, using the > > high-speed Tegra serial driver won't exhibit the issue as clocks are > > dynamically enabled/disabled on every access. > >=20 > > This has been reproduced both on Apalis T30 as well as Apalis TK1 but > > may be an issue on all Tegra UARTB's which share the clock enable with > > VFIR. > >=20 >=20 > Ah.. the correct fix for this is to initialize the enable_refcnt based on= the > hw state. This is done in 9619dba8325fce098bbc9ee2911d1b0150fec0c9 for > periph gate clocks, but obviously also applies to normal periph clocks. Hi Marcel, were you going to send a new version with the alternative fix as suggested by Peter? Thierry --924gEkU1VlJlwnwX Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAlv+XrMACgkQ3SOs138+ s6GXtg/+IuuqToPbfBDICYwJJQ8uXHPGJXDS+Z7bthtYwuqo5M2r3s5Bvnxek+Sn hGHjVuPBc5vcM/JoD2UrSO086bREgody0yDunjDQdQDCkw1sJ/JM3YUz7amHabkg mWrEKDaf7k9Xs4KKBHyq67mpgn/WA2+Zyjtp7LX6sYGFaKTe2Qa8NHUtVdh0YKTL Mie6WfoFjpSkx/YghDIV8WorY8SLa9mN698H2f75HTAWRF2UaVj+VtbGrYWlUWzy NP14u8Gp4yYqQ/Xv3Lq0rtEDUA8u7QedSh8ICYAPyEUljbi1tVuyeHSjktLHFUrF bCeqyLgePdq5icyF2ipPmW4kx6Nsy6iMwlbQeDWwg8Dw4WNo6qZPhWwsG/LVCQiq L30BlkmKG75J4urufG8uRvIKzRNhd9t4ABWVOrbM+XyPB8gE/I3u3WrSvygIyGXl PL+QWQzUMJMW+PLnGa7ZVEZJn6CwB/fHpxq/HHiNZhPK+v1K1ww54cwRue2+RjXm A8A4bwXD5A+qU0EWUZZo0mk7TsUgAaeLY5sFI0fEKMNXtL6m2ceOGhipQjA8cVOr 2V2bFCetZJGtPezJVUuhzGEZRd+R46FvhNDkGPA2xQ80Fbenja2DBZs+e78XTrXu bLnF79vVm+dzUoeV1D/XLaBBzkHJ1mKW/ZFBtQiCJm7G/AT3Zo0= =cuvx -----END PGP SIGNATURE----- --924gEkU1VlJlwnwX--