From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dinh Nguyen Subject: Re: [PATCHv5] drivers/amba: add reset control to amba bus probe Date: Wed, 28 Aug 2019 08:34:20 -0500 Message-ID: <46bcf493-9dd6-bf5b-089a-be158739a13f@kernel.org> References: <20190826154252.22952-1-dinguyen@kernel.org> <30608.1566933924@turing-police> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <30608.1566933924@turing-police> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: =?UTF-8?Q?Valdis_Kl=c4=93tnieks?= Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, robh@kernel.org, linux@armlinux.org.uk, frowand.list@gmail.com, keescook@chromium.org, anton@enomsg.org, ccross@android.com, tony.luck@intel.com, daniel.thompson@linaro.org, linus.walleij@linaro.org, manivannan.sadhasivam@linaro.org, linux-arm-kernel@lists.infradead.org, p.zabel@pengutronix.de List-Id: devicetree@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 8/27/19 2:25 PM, Valdis Kl?tnieks wrote: > On Mon, 26 Aug 2019 10:42:52 -0500, Dinh Nguyen said: >> The primecell controller on some SoCs, i.e. SoCFPGA, is held in >> reset by default. Until recently, the DMA controller was brought >> out of reset by the bootloader(i.e. U-Boot). But a recent change >> in U-Boot, the peripherals that are not used are held in reset >> and are left to Linux to bring them out of reset. >> >> Add a mechanism for getting the reset property and de-assert the >> primecell module from reset if found. This is a not a hard fail >> if the reset properti is not present in the device tree node, so >> the driver will continue to probe. > > Does this DTRT for both old and new U-Boots? My naive reading of > this patch What is a DTRT? > says on an old U-Boot, we end up attempting to bring it out of > reset even though they had already been brought out. > If the peripheral is already out of reset, de-asserting the reset has no affect. Dinh -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEoHhMeiyk5VmwVMwNGZQEC4GjKPQFAl1mgtYACgkQGZQEC4Gj KPRKMRAArFO9bQ7FCE4oiVgO/sOLm2M/ngGD3Czi6Y8TcAbIk4EylBGVw634Gs4Z v5vuyxShlfApBb0PqfhLOo5cXrTyMdpWOq9AQ4vEcEU2MPKN8QcyLczvEagyYcwA ianhTLR21v1Gdfm5MHqpKrNxSrb6Nt6cWmYCXjpabLYZg0gKJnsYl2XheHIdUJ02 kD2P6sQC3mf3OC5Gou4JXZGvDMgEwLG9lHsb7YoFq6tzZW3YQvAi3HcxIZZh4J8b jFcPR3RxxQgGwESEGDWQu2EzY/d9qStEQ9VYHl/v6QIL77S1oXUAXLbh3e6ZoSgt M93eK2G9wGCL5JlUbHXQ402OfewHchgQW1bDpjkaZLL+d9jUiGLqALAj0Az2FqX1 HtPPtifB4z6TuaLkxNTZ1Oz7UR0cWtKeSYjsuIwi0XzQMXopgH7oKdzJajNlAfRJ In6fSVuwp47p43wj2dmUtuCSYvzKTHAg/sVGaufEfsT8ZINSOZJY9ivDqkJIzlDR nsOclhfOGs5PgL4NPFW5U5O58DzZ5yl9NEotB4ahacuOqJv1PUdT3gABbL5hUogx QTAPNREbYesG3osFLeEXeachiNChyJ7r+NyWFly7RXA/ukxoer2Rkxt3h0hQib6Q /jhAsa1ar1NEk8dJJfNO7R5pZkG7ZCbhzuSDKPB2yRZPDeQGol8= =SFzc -----END PGP SIGNATURE-----