From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4FC21C3A59F for ; Mon, 26 Aug 2019 15:51:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3058E21848 for ; Mon, 26 Aug 2019 15:51:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731518AbfHZPvu (ORCPT ); Mon, 26 Aug 2019 11:51:50 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:41043 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727850AbfHZPvs (ORCPT ); Mon, 26 Aug 2019 11:51:48 -0400 Received: from lupine.hi.pengutronix.de ([2001:67c:670:100:3ad5:47ff:feaf:1a17] helo=lupine) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1i2HHW-0007Po-QI; Mon, 26 Aug 2019 17:51:46 +0200 Message-ID: <1566834704.3842.7.camel@pengutronix.de> Subject: Re: [PATCHv5] drivers/amba: add reset control to amba bus probe From: Philipp Zabel To: Dinh Nguyen , linux-kernel@vger.kernel.org Cc: 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 Date: Mon, 26 Aug 2019 17:51:44 +0200 In-Reply-To: <20190826154252.22952-1-dinguyen@kernel.org> References: <20190826154252.22952-1-dinguyen@kernel.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:3ad5:47ff:feaf:1a17 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2019-08-26 at 10:42 -0500, Dinh Nguyen wrote: > 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. > > Because there are different variants of the controller that may have > multiple reset signals, the code will find all reset(s) specified and > de-assert them. > > Signed-off-by: Dinh Nguyen > Reviewed-by: Rob Herring > --- > v5: use of_reset_control_array_get_optional_shared() > v4: cleaned up indentation in loop > fix up a few checkpatch warnings > add Reviewed-by: > v3: add a reset_control_put() > add error handling > v2: move reset control to bus code > find all reset properties and de-assert them > --- > drivers/amba/bus.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > index 100e798a5c82..f8a7cb74c3cf 100644 > --- a/drivers/amba/bus.c > +++ b/drivers/amba/bus.c > @@ -18,6 +18,7 @@ > #include > #include > #include > +#include > > #include > > @@ -401,6 +402,24 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent) > ret = amba_get_enable_pclk(dev); > if (ret == 0) { > u32 pid, cid; > + int count; > + struct reset_control *rstc; > + > + /* > + * Find reset control(s) of the amba bus and de-assert them. > + */ > + count = reset_control_get_count(&dev->dev); > + while (count > 0) { > + rstc = of_reset_control_array_get_optional_shared(dev->dev.of_node); You can drop the loop, the rstc returned by of_reset_control_array_get() already controls all resets together. regards Philipp