From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751842AbdBODjK (ORCPT ); Tue, 14 Feb 2017 22:39:10 -0500 Received: from regular1.263xmail.com ([211.150.99.139]:50287 "EHLO regular1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751516AbdBODjJ (ORCPT ); Tue, 14 Feb 2017 22:39:09 -0500 X-263anti-spam: KSV:0; X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-RL-SENDER: zyw@rock-chips.com X-FST-TO: linux-kernel@vger.kernel.org X-SENDER-IP: 220.128.92.125 X-LOGIN-NAME: zyw@rock-chips.com X-UNIQUE-TAG: <885a52b6e44d87118a77d11c206684ac> X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [PATCH v3 23/24] drm/rockchip: dw-mipi-dsi: add reset control To: John Keeping , Mark Yao References: <20170129132444.25251-1-john@metanate.com> <20170129132444.25251-24-john@metanate.com> Cc: dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org From: Chris Zhong Message-ID: <58A3CD45.9090309@rock-chips.com> Date: Wed, 15 Feb 2017 11:38:45 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <20170129132444.25251-24-john@metanate.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi John On 01/29/2017 09:24 PM, John Keeping wrote: > In order to fully reset the state of the MIPI controller we must assert > this reset. > > This is slightly more complicated than it could be in order to maintain > compatibility with device trees that do not specify the reset property. > > Signed-off-by: John Keeping > Reviewed-by: Chris Zhong > --- > v3: > - Add Chris' Reviewed-by > Unchanged in v2 > > drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > index 58cb8ace2fe8..cf3ca6b0cbdb 100644 > --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -1124,6 +1125,7 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master, > of_match_device(dw_mipi_dsi_dt_ids, dev); > const struct dw_mipi_dsi_plat_data *pdata = of_id->data; > struct platform_device *pdev = to_platform_device(dev); > + struct reset_control *apb_rst; > struct drm_device *drm = data; > struct dw_mipi_dsi *dsi; > struct resource *res; > @@ -1162,6 +1164,34 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master, > return ret; > } > > + /* > + * Note that the reset was not defined in the initial device tree, so > + * we have to be prepared for it not being found. > + */ > + apb_rst = devm_reset_control_get(dev, "apb"); > + if (IS_ERR(apb_rst)) { > + if (PTR_ERR(apb_rst) == -ENODEV) { According to [0], I think it should be -ENOENT here. [0] https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=3d81216fde465e76c5eae98f61d3666163634395 commit 3d81216fde465e76c5eae98f61d3666163634395 Author: Alban Bedel Date: Tue Sep 1 17:28:31 2015 +0200 reset: Fix of_reset_control_get() for consistent return values When of_reset_control_get() is called without connection ID it returns -ENOENT when the 'resets' property doesn't exists or is an empty entry. However when a connection ID is given it returns -EINVAL when the 'resets' property doesn't exists or the requested name can't be found. This is because the error code returned by of_property_match_string() is just passed down as an index to of_parse_phandle_with_args(), which then returns -EINVAL. To get a consistent return value with both code paths we must return -ENOENT when of_property_match_string() fails. Signed-off-by: Alban Bedel Signed-off-by: Philipp Zabel > + apb_rst = NULL; > + } else { > + dev_err(dev, "Unable to get reset control: %d\n", ret); > + return PTR_ERR(apb_rst); > + } > + } > + > + if (apb_rst) { > + ret = clk_prepare_enable(dsi->pclk); > + if (ret) { > + dev_err(dev, "%s: Failed to enable pclk\n", __func__); > + return ret; > + } > + > + reset_control_assert(apb_rst); > + usleep_range(10, 20); > + reset_control_deassert(apb_rst); > + > + clk_disable_unprepare(dsi->pclk); > + } > + > ret = clk_prepare_enable(dsi->pllref_clk); > if (ret) { > dev_err(dev, "%s: Failed to enable pllref_clk\n", __func__);