From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH] clk: tegra: Fix bypassing of PLLs Date: Wed, 25 Nov 2015 16:11:00 +0100 Message-ID: <20151125151100.GA31492@ulmo.nvidia.com> References: <1448032264-29622-1-git-send-email-jonathanh@nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="J/dobhs11T7y2rNN" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Tyler Baker Cc: Jon Hunter , Peter De Schrijver , Prashant Gaikwad , Michael Turquette , Stephen Boyd , Stephen Warren , Alexandre Courbot , linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, "linux-kernel@vger.kernel.org" , Rhyland Klein , Kevin's boot bot List-Id: linux-tegra@vger.kernel.org --J/dobhs11T7y2rNN Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 23, 2015 at 03:18:59PM -0800, Tyler Baker wrote: > Hi Jon, >=20 > On 20 November 2015 at 07:11, Jon Hunter wrote: > > The _clk_disable_pll() function will attempt to place a PLL into bypass > > if the TEGRA_PLL_BYPASS is specified for the PLL and then disable the P= LL > > by clearing the enable bit. To place the PLL into bypass, the bypass bit > > needs to be set and not cleared. Fix this by setting the bypass bit and > > not clearing it. > > > > Signed-off-by: Jon Hunter >=20 > The kernelci.org bot recently detected a jetson-tk1 boot failure[1][2] > in the tegra tree. This boot failure has only been observed when > booting with a multi_v7_defconfig kernel variant. The bot bisected[3] > this boot failure to this commit, and I confirmed reverting it on top > of the tegra for-next branch resolves the issue. The ramdisk[4] used > for booting is loaded with the modules from the build. It appears to > me that as the modules are being loaded in userspace by eudev the > jetson-tk1 locks up. I've sifted through the console logs a bit, and > found this splat to be most interesting[5]. Can you confirm this > issue on your end? Just to close the loop on this: we've discussed this on IRC and came to the conclusion that not using the bypass mode is safer (switching into and out of bypass can glitch). I've dropped this patch for now and Jon will be looking into a second revision of the patch which, in addition to fixing bypass (the fix is legit, it just happens to break because of the glitch, most likely), will also remove the BYPASS flag setting so that bypass will not be used. Thierry --J/dobhs11T7y2rNN Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJWVc+EAAoJEN0jrNd/PrOhkWUP/AmnuVSCyL5xK0fb5lqCYVAb /iG/OpI1hGBhzHQFvFTSP/7cL/fmkWfJ5Huq/PYlVviO8NCx7E0S1MbhYGV+asbq XJ5zDSf1f3cYVN58wqtx7MqPT+bxAbTxr4kbqvgHzSK8XVXIRgS7E7qu6YZHylbj TPSKrny40KeYRCg4f6lZHO0LrekC5dq2lzbL7gleWt3cs7FYdKH9m75Ph38ajbgW SpXFhqETrvoym4zaNdOMdHDwa8HFDDMtxaTLWSVwbTYguhDRWrDwiR19RRZwjhn/ K0HlEGD+2sf6Ve8UN1EK+M52GKwPLeeFF5n+vsOWTtGA7gw29mIFXDyi8W/8tmXy ULwD7S/rn4wizHqwfEPzTmiAPBlUf38hIL5b2QXlkLxfbrYnasFkcpOSJQ5kGZOy Do0nlHB+NdtvDoYkWMw1c9c5bEt4XyOX/5QLhWW7WecD+kpUv5OhoDsDR+f/aHZU /ppFDVkxXoZePGREGx8rJtktBX6oU/x4ABipjdpFhITPJOGLLnI3rXhRgoxFnq6Y o2+Hx0vxVAh9AidZZEohd3lPqV3ubqhL2wk4dyXCnN0UbUmkR0/3rGkT9peHOooN ylD7RMLQcCX68LojOW7MHqIqjT/9bum1JJkXv4V/E8KNRpo/NqX4FaTXIbz6tB2L aYtVCuaujLi7cA56gsjL =iJcY -----END PGP SIGNATURE----- --J/dobhs11T7y2rNN--