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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7B60ECAAD8 for ; Tue, 13 Sep 2022 17:15:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232715AbiIMRPd (ORCPT ); Tue, 13 Sep 2022 13:15:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232474AbiIMROl (ORCPT ); Tue, 13 Sep 2022 13:14:41 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63E2E183AD for ; Tue, 13 Sep 2022 09:03:18 -0700 (PDT) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oY7e1-0005K2-JO; Tue, 13 Sep 2022 17:16:13 +0200 Received: from sha by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1oY7e1-0001yU-1A; Tue, 13 Sep 2022 17:16:13 +0200 Date: Tue, 13 Sep 2022 17:16:12 +0200 From: Sascha Hauer To: Vinod Koul Cc: Dario Binacchi , linux-kernel@vger.kernel.org, linux-amarula@amarulasolutions.com, Michael Trimarchi , stable@vger.kernel.org, Fabio Estevam , NXP Linux Team , Pengutronix Kernel Team , Shawn Guo , dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3] dmaengine: mxs: fix driver registering Message-ID: <20220913151612.GI12909@pengutronix.de> References: <20220614101751.3636028-1-dario.binacchi@amarulasolutions.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: dmaengine@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Hi Vinod, On Thu, Jun 16, 2022 at 06:58:43AM -0700, Vinod Koul wrote: > On 14-06-22, 12:17, Dario Binacchi wrote: > > Driver registration fails on SOC imx8mn as its supplier, the clock > > control module, is not ready. Since platform_driver_probe(), as > > reported by its description, is incompatible with deferred probing, > > we have to use platform_driver_register(). > > > > Fixes: a580b8c5429a ("dmaengine: mxs-dma: add dma support for i.MX23/28") > > Co-developed-by: Michael Trimarchi > > Signed-off-by: Michael Trimarchi > > Signed-off-by: Dario Binacchi > > Cc: stable@vger.kernel.org > > > > --- > > > > Changes in v3: > > - Restore __init in front of mxs_dma_init() definition. > > > > Changes in v2: > > - Add the tag "Cc: stable@vger.kernel.org" in the sign-off area. > > > > drivers/dma/mxs-dma.c | 9 +++------ > > 1 file changed, 3 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c > > index 994fc4d2aca4..6e90540fedc4 100644 > > --- a/drivers/dma/mxs-dma.c > > +++ b/drivers/dma/mxs-dma.c > > @@ -741,7 +741,7 @@ static struct dma_chan *mxs_dma_xlate(struct of_phandle_args *dma_spec, > > ofdma->of_node); > > } > > > > -static int __init mxs_dma_probe(struct platform_device *pdev) > > +static int mxs_dma_probe(struct platform_device *pdev) > > why drop __init here, if there is a reason for that please split this > change and document such reason... The reason for dropping __init comes with this patch. With platform_driver_probe() the probe function is called only once, during init time. The problem with platform_driver_probe() is that the probe function will never be called again when it initially returns -EPROBE_DEFER. That's a problem for Dario: The clock is not yet available, the driver defers probe and will never be probed again when the clock is finally available. With platform_driver_register() to which this patch switches to the probe function can be called at any time, thus __init has to be removed. For what it's worth: Acked-by: Sascha Hauer for this patch. Sascha > > > { > > struct device_node *np = pdev->dev.of_node; > > const struct mxs_dma_type *dma_type; > > @@ -839,10 +839,7 @@ static struct platform_driver mxs_dma_driver = { > > .name = "mxs-dma", > > .of_match_table = mxs_dma_dt_ids, > > }, > > + .probe = mxs_dma_probe, > > }; > > > > -static int __init mxs_dma_module_init(void) > > -{ > > - return platform_driver_probe(&mxs_dma_driver, mxs_dma_probe); > > -} > > -subsys_initcall(mxs_dma_module_init); > > +module_platform_driver(mxs_dma_driver); > > -- > > 2.32.0 > > -- > ~Vinod > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E120BC6FA82 for ; Tue, 13 Sep 2022 15:29:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=UsQPwONjEESJFz928dV5J6IgQNTL49jIRG2E9eGQQsI=; b=rCcICTlNxkmFl0 yF8yrzRZW3EyfZg3UhMlJ7gNAC45HUBrHqxZsweUBvgGJD5VxJ5u/mxDlix+8MXehrVrfD49enXDH 3sJID2gcC+y1MDbAJ2k7a3B6x/L/3j6zV5LiwPqe8RhCWp4EBHztQfWzCHEJZUhoivq7sC8cNHoRS HzNu4As/wcE0B9S7RLqDq5BfntVZqlZADNvJTzgV5gSw9kKEbvQRTpf4uRuZ4axkvwARcTiyimcoB LqH0NBTFky0gnPVL7o0N31pn3BTzzhiOpWzQCirobT8Iyay8/fuzv7uE7HhF+X+2X/jNtIX8oLDt/ cR5OV7Ps1lyP4C+r+VUQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oY7pa-00CVN1-Fi; Tue, 13 Sep 2022 15:28:10 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oY7g4-00CM16-5j for linux-arm-kernel@lists.infradead.org; Tue, 13 Sep 2022 15:18:22 +0000 Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oY7e1-0005K2-JO; Tue, 13 Sep 2022 17:16:13 +0200 Received: from sha by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1oY7e1-0001yU-1A; Tue, 13 Sep 2022 17:16:13 +0200 Date: Tue, 13 Sep 2022 17:16:12 +0200 From: Sascha Hauer To: Vinod Koul Cc: Dario Binacchi , linux-kernel@vger.kernel.org, linux-amarula@amarulasolutions.com, Michael Trimarchi , stable@vger.kernel.org, Fabio Estevam , NXP Linux Team , Pengutronix Kernel Team , Shawn Guo , dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3] dmaengine: mxs: fix driver registering Message-ID: <20220913151612.GI12909@pengutronix.de> References: <20220614101751.3636028-1-dario.binacchi@amarulasolutions.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220913_081820_246219_7D63A80A X-CRM114-Status: GOOD ( 35.46 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Vinod, On Thu, Jun 16, 2022 at 06:58:43AM -0700, Vinod Koul wrote: > On 14-06-22, 12:17, Dario Binacchi wrote: > > Driver registration fails on SOC imx8mn as its supplier, the clock > > control module, is not ready. Since platform_driver_probe(), as > > reported by its description, is incompatible with deferred probing, > > we have to use platform_driver_register(). > > > > Fixes: a580b8c5429a ("dmaengine: mxs-dma: add dma support for i.MX23/28") > > Co-developed-by: Michael Trimarchi > > Signed-off-by: Michael Trimarchi > > Signed-off-by: Dario Binacchi > > Cc: stable@vger.kernel.org > > > > --- > > > > Changes in v3: > > - Restore __init in front of mxs_dma_init() definition. > > > > Changes in v2: > > - Add the tag "Cc: stable@vger.kernel.org" in the sign-off area. > > > > drivers/dma/mxs-dma.c | 9 +++------ > > 1 file changed, 3 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c > > index 994fc4d2aca4..6e90540fedc4 100644 > > --- a/drivers/dma/mxs-dma.c > > +++ b/drivers/dma/mxs-dma.c > > @@ -741,7 +741,7 @@ static struct dma_chan *mxs_dma_xlate(struct of_phandle_args *dma_spec, > > ofdma->of_node); > > } > > > > -static int __init mxs_dma_probe(struct platform_device *pdev) > > +static int mxs_dma_probe(struct platform_device *pdev) > > why drop __init here, if there is a reason for that please split this > change and document such reason... The reason for dropping __init comes with this patch. With platform_driver_probe() the probe function is called only once, during init time. The problem with platform_driver_probe() is that the probe function will never be called again when it initially returns -EPROBE_DEFER. That's a problem for Dario: The clock is not yet available, the driver defers probe and will never be probed again when the clock is finally available. With platform_driver_register() to which this patch switches to the probe function can be called at any time, thus __init has to be removed. For what it's worth: Acked-by: Sascha Hauer for this patch. Sascha > > > { > > struct device_node *np = pdev->dev.of_node; > > const struct mxs_dma_type *dma_type; > > @@ -839,10 +839,7 @@ static struct platform_driver mxs_dma_driver = { > > .name = "mxs-dma", > > .of_match_table = mxs_dma_dt_ids, > > }, > > + .probe = mxs_dma_probe, > > }; > > > > -static int __init mxs_dma_module_init(void) > > -{ > > - return platform_driver_probe(&mxs_dma_driver, mxs_dma_probe); > > -} > > -subsys_initcall(mxs_dma_module_init); > > +module_platform_driver(mxs_dma_driver); > > -- > > 2.32.0 > > -- > ~Vinod > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel