Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756053AbcC2GKV (ORCPT ); Tue, 29 Mar 2016 02:10:21 -0400 Received: from lucky1.263xmail.com ([211.157.147.131]:58430 "EHLO lucky1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755964AbcC2GJw (ORCPT ); Tue, 29 Mar 2016 02:09:52 -0400 X-263anti-spam: KSV:0; X-MAIL-GRAY: 1 X-MAIL-DELIVERY: 0 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED: 0 X-RL-SENDER: shawn.lin@rock-chips.com X-FST-TO: zhangfei.gao@linaro.org X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: shawn.lin@rock-chips.com X-UNIQUE-TAG: <410d72dc1340c9075b7b9b1801014538> X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [PATCH 2/2] mmc: dw_mmc: add resets support to dw_mmc To: Jaehoon Chung , Guodong Xu References: <1457254062-22677-1-git-send-email-guodong.xu@linaro.org> <1457254062-22677-2-git-send-email-guodong.xu@linaro.org> <56DC3BAD.8020107@rock-chips.com> <56F9E6E5.9000100@kernel-upstream.org> <56FA192A.9030209@samsung.com> Cc: shawn.lin@rock-chips.com, robh+dt@kernel.org, =?UTF-8?Q?Pawe=c5=82_Moll?= , Mark Rutland , ijc+devicetree@hellion.org.uk, Kumar Gala , Ulf Hansson , devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , linux-mmc@vger.kernel.org, Xinwei Kong , Zhangfei Gao From: Shawn Lin Message-ID: <56FA1C1C.4090008@rock-chips.com> Date: Tue, 29 Mar 2016 14:09:32 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <56FA192A.9030209@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6886 Lines: 207 在 2016/3/29 13:56, Jaehoon Chung 写道: > On 03/29/2016 11:22 AM, Shawn Lin wrote: >> 在 2016/3/25 13:35, Guodong Xu 写道: >>> Hi, Shawn >>> >>> Sorry I replied late. I added comments below. >>> >>> On 6 March 2016 at 22:16, Shawn Lin >> > wrote: >>> >>> On 2016/3/6 16:47, Guodong Xu wrote: >>> >>> mmc registers may in abnormal state if mmc is used in bootloader, >>> eg. to support booting from eMMC. So we need reset mmc registers >>> when kernel boots up, instead of assuming mmc is in clean state. >>> >>> With this patch, user can add a 'resets' property into dw_mmc dts >>> node. When driver parse_dt and probe, it calls reset API to >>> deassert the 'reset' of dw_mmc host controller. When probe error or >>> remove, it calls reset API to assert it. >>> >>> Please also refer to >>> Documentation/devicetree/bindings/reset/reset.txt >>> >>> Signed-off-by: Guodong Xu >> > >>> Signed-off-by: Xinwei Kong >> > >>> Signed-off-by: Zhangfei Gao >> > >>> >>> >>> Really should V2 and add the changelog. >>> >>> >>> Yes, will do. next version I sent will be labelled as V3. >>> >>> >>> >>> --- >>> drivers/mmc/host/dw_mmc.c | 22 +++++++++++++++++++++- >>> 1 file changed, 21 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >>> index 242f9a0..281ea9c 100644 >>> --- a/drivers/mmc/host/dw_mmc.c >>> +++ b/drivers/mmc/host/dw_mmc.c >>> @@ -2878,6 +2878,14 @@ static struct dw_mci_board >>> *dw_mci_parse_dt(struct dw_mci *host) >>> if (!pdata) >>> return ERR_PTR(-ENOMEM); >>> >>> + /* find reset controller when exist */ >>> + pdata->rstc = devm_reset_control_get_optional(dev, NULL); >>> + if (IS_ERR(pdata->rstc)) { >>> + if (PTR_ERR(pdata->rstc) == -EPROBE_DEFER) >>> + return ERR_PTR(-EPROBE_DEFER); >>> + pdata->rstc = NULL; >>> >>> >>> maybe we can remove "pdata->rstc = NULL", and directly >>> use IS_ERR(..) for the following "if (host->pdata->rstc != NULL)" >>> statement >>> >>> >>> Yes, will do. >>> I see your point, other lines in this file are using IS_ERR(!..), I will >>> use this style too. >>> >>> + } >>> + >>> /* find out number of slots supported */ >>> of_property_read_u32(np, "num-slots", &pdata->num_slots); >>> >>> @@ -2949,7 +2957,9 @@ int dw_mci_probe(struct dw_mci *host) >>> >>> if (!host->pdata) { >>> host->pdata = dw_mci_parse_dt(host); >>> - if (IS_ERR(host->pdata)) { >>> + if (PTR_ERR(host->pdata) == -EPROBE_DEFER) >>> + return -EPROBE_DEFER; >>> >>> >>> please fix the coding style here. >>> >>> >>> Do you mean to add additional {} for this 'if' , like this? >>> >>> + if (PTR_ERR(host->pdata) == -EPROBE_DEFER) { >>> + return -EPROBE_DEFER; >>> >>> + } >>> >>> I will add {}. >>> >>> >>> >>> + else if (IS_ERR(host->pdata)) { >>> dev_err(host->dev, "platform data not >>> available\n"); >>> return -EINVAL; >>> } >>> @@ -3012,6 +3022,9 @@ int dw_mci_probe(struct dw_mci *host) >>> } >>> } >>> >>> + if (host->pdata->rstc != NULL) >>> + reset_control_deassert(host->pdata->rstc); >>> + >>> >>> >>> sorry, I can't follow your intention here. Shouldn't it be something >>> like "assert mmc -> may need delay -> deassert mmc". As your current >>> code, nothing happend right? >>> >>> >>> The chip exits from bootloader with this bit asserted. And when entering >>> kernel, we only need to deassert. >>> >>> In my current code, the driver deassert mmc in _probe(), and assert mmc >>> in _remove(). >> >> I catch your point. From the previous discussion, we add it to make sure >> dw_mmc in good state after leaving bootloader to kernel. But My real question is that you can assert it in bootloader, so you can also >> dessert it in bootloaer to make sure dw_mmc work fine when probing >> in kernel. In that way, we don't need this patch? > > Doesn't dw_mci_hw_reset work fine? I think that card should be reset with MMC_CAP_HW_RESET. > Could you check this? > MMC_CAP_HW_RESET actually reset the mmc card, but Guodong means to reset the controller rather than mmc card :) > Best Regards, > Jaehoon Chung > >> >> More to think, Is it ok to match the behaviour of bootloader stage? >> My bootloader doesn't assert the reset pin of dw_mmc, so it seams if >> I want to fix you issue on kernel stage, I need a new round of >> assert->delay->deassert. >> >> >>> >>> >>> >>> setup_timer(&host->cmd11_timer, >>> dw_mci_cmd11_timer, (unsigned long)host); >>> >>> @@ -3164,6 +3177,9 @@ err_dmaunmap: >>> if (host->use_dma && host->dma_ops->exit) >>> host->dma_ops->exit(host); >>> >>> + if (host->pdata->rstc != NULL) >>> + reset_control_assert(host->pdata->rstc); >>> + >>> err_clk_ciu: >>> if (!IS_ERR(host->ciu_clk)) >>> clk_disable_unprepare(host->ciu_clk); >>> @@ -3196,11 +3212,15 @@ void dw_mci_remove(struct dw_mci *host) >>> if (host->use_dma && host->dma_ops->exit) >>> host->dma_ops->exit(host); >>> >>> + if (host->pdata->rstc != NULL) >>> + reset_control_assert(host->pdata->rstc); >>> + >>> if (!IS_ERR(host->ciu_clk)) >>> clk_disable_unprepare(host->ciu_clk); >>> >>> if (!IS_ERR(host->biu_clk)) >>> clk_disable_unprepare(host->biu_clk); >>> + >>> } >>> >>> >>> unnecessary new line here. >>> >>> >>> Will fix. >>> >>> -Guodong >>> >>> >>> EXPORT_SYMBOL(dw_mci_remove); >>> >>> >>> >>> >>> -- >>> Best Regards >>> Shawn Lin >>> >>> >> >> >> > > > > -- Best Regards Shawn Lin