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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URI_HEX, USER_AGENT_SANE_1 autolearn=unavailable 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 BE14DC33C9E for ; Thu, 30 Jan 2020 09:42:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FDD2214DB for ; Thu, 30 Jan 2020 09:42:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="WD+8d45Z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727174AbgA3Jmr (ORCPT ); Thu, 30 Jan 2020 04:42:47 -0500 Received: from lelv0142.ext.ti.com ([198.47.23.249]:54516 "EHLO lelv0142.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726873AbgA3Jmr (ORCPT ); Thu, 30 Jan 2020 04:42:47 -0500 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 00U9ganA011927; Thu, 30 Jan 2020 03:42:36 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1580377356; bh=vmHw7UFWIoxsoLu0lFcIEhK30xYRE7CF6RQRjKrMXjc=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=WD+8d45ZkSf28l85jT6CNEFPxGaD/QeFowB3xwDmHtNFCntlH2IMazAI8iHbEmPqU AZv8CNjkCiPD8xnjDG94RG7KA6NMvkTBeBHAi+hvOIdNmgaUlavLezBHhovwzPjQzp G9QjF0RYGqQXwYHZJ5UzC++Rys25nAIR7iTQo3rs= Received: from DFLE108.ent.ti.com (dfle108.ent.ti.com [10.64.6.29]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTP id 00U9gaHm105194; Thu, 30 Jan 2020 03:42:36 -0600 Received: from DFLE115.ent.ti.com (10.64.6.36) by DFLE108.ent.ti.com (10.64.6.29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3; Thu, 30 Jan 2020 03:42:35 -0600 Received: from lelv0326.itg.ti.com (10.180.67.84) by DFLE115.ent.ti.com (10.64.6.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3 via Frontend Transport; Thu, 30 Jan 2020 03:42:35 -0600 Received: from [192.168.2.6] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id 00U9gXIh039641; Thu, 30 Jan 2020 03:42:34 -0600 Subject: Re: [PATCH v2] dmaengine: Create symlinks between DMA channels and slaves To: Geert Uytterhoeven , Vinod Koul , Dan Williams CC: , , References: <20200117153056.31363-1-geert+renesas@glider.be> From: Peter Ujfalusi Message-ID: Date: Thu, 30 Jan 2020 11:43:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200117153056.31363-1-geert+renesas@glider.be> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Geert, On 17/01/2020 17.30, Geert Uytterhoeven wrote: > Currently it is not easy to find out which DMA channels are in use, and > which slave devices are using which channels. > > Fix this by creating two symlinks between the DMA channel and the actual > slave device when a channel is requested: > 1. A "slave" symlink from DMA channel to slave device, > 2. A "dma:" symlink slave device to DMA channel. > When the channel is released, the symlinks are removed again. > The latter requires keeping track of the slave device and the channel > name in the dma_chan structure. > > Note that this is limited to channel request functions for requesting an > exclusive slave channel that take a device pointer (dma_request_chan() > and dma_request_slave_channel*()). > > Signed-off-by: Geert Uytterhoeven > --- > v2: > - Add DMA_SLAVE_NAME macro, > - Also handle channels from FIXME, > - Add backlinks from slave device to DMA channel, > > On r8a7791/koelsch, the following new symlinks are created: > > /sys/devices/platform/soc/ > ├── e6700000.dma-controller/dma/dma0chan0/slave -> ../../../e6e20000.spi > ├── e6700000.dma-controller/dma/dma0chan1/slave -> ../../../e6e20000.spi > ├── e6700000.dma-controller/dma/dma0chan2/slave -> ../../../ee100000.sd > ├── e6700000.dma-controller/dma/dma0chan3/slave -> ../../../ee100000.sd > ├── e6700000.dma-controller/dma/dma0chan4/slave -> ../../../ee160000.sd > ├── e6700000.dma-controller/dma/dma0chan5/slave -> ../../../ee160000.sd > ├── e6700000.dma-controller/dma/dma0chan6/slave -> ../../../e6e68000.serial > ├── e6700000.dma-controller/dma/dma0chan7/slave -> ../../../e6e68000.serial > ├── e6720000.dma-controller/dma/dma1chan0/slave -> ../../../e6b10000.spi > ├── e6720000.dma-controller/dma/dma1chan1/slave -> ../../../e6b10000.spi > ├── e6720000.dma-controller/dma/dma1chan2/slave -> ../../../ee140000.sd > ├── e6720000.dma-controller/dma/dma1chan3/slave -> ../../../ee140000.sd > ├── e6b10000.spi/dma:rx -> ../e6720000.dma-controller/dma/dma1chan1 > ├── e6b10000.spi/dma:tx -> ../e6720000.dma-controller/dma/dma1chan0 > ├── e6e20000.spi/dma:rx -> ../e6700000.dma-controller/dma/dma0chan1 > ├── e6e20000.spi/dma:tx -> ../e6700000.dma-controller/dma/dma0chan0 > ├── e6e68000.serial/dma:rx -> ../e6700000.dma-controller/dma/dma0chan7 > ├── e6e68000.serial/dma:tx -> ../e6700000.dma-controller/dma/dma0chan6 > ├── ee100000.sd/dma:rx -> ../e6700000.dma-controller/dma/dma0chan3 > ├── ee100000.sd/dma:tx -> ../e6700000.dma-controller/dma/dma0chan2 > ├── ee140000.sd/dma:rx -> ../e6720000.dma-controller/dma/dma1chan3 > ├── ee140000.sd/dma:tx -> ../e6720000.dma-controller/dma/dma1chan2 > ├── ee160000.sd/dma:rx -> ../e6700000.dma-controller/dma/dma0chan5 > └── ee160000.sd/dma:tx -> ../e6700000.dma-controller/dma/dma0chan4 > > On r8a77951/salvator-xs: > > /sys/devices/platform/soc/ > ├── e6460000.dma-controller/dma/dma4chan0/slave -> ../../../e659c000.usb > ├── e6460000.dma-controller/dma/dma4chan1/slave -> ../../../e659c000.usb > ├── e6470000.dma-controller/dma/dma5chan0/slave -> ../../../e659c000.usb > ├── e6470000.dma-controller/dma/dma5chan1/slave -> ../../../e659c000.usb > ├── e6510000.i2c/dma:tx -> ../e7300000.dma-controller/dma/dma7chan0 > ├── e6550000.serial/dma:rx -> ../e7310000.dma-controller/dma/dma8chan1 > ├── e6550000.serial/dma:tx -> ../e7310000.dma-controller/dma/dma8chan0 > ├── e6590000.usb/dma:ch0 -> ../e65a0000.dma-controller/dma/dma2chan0 > ├── e6590000.usb/dma:ch1 -> ../e65a0000.dma-controller/dma/dma2chan1 > ├── e6590000.usb/dma:ch2 -> ../e65b0000.dma-controller/dma/dma3chan0 > ├── e6590000.usb/dma:ch3 -> ../e65b0000.dma-controller/dma/dma3chan1 > ├── e659c000.usb/dma:ch0 -> ../e6460000.dma-controller/dma/dma4chan0 > ├── e659c000.usb/dma:ch1 -> ../e6460000.dma-controller/dma/dma4chan1 > ├── e659c000.usb/dma:ch2 -> ../e6470000.dma-controller/dma/dma5chan0 > ├── e659c000.usb/dma:ch3 -> ../e6470000.dma-controller/dma/dma5chan1 > ├── e65a0000.dma-controller/dma/dma2chan0/slave -> ../../../e6590000.usb > ├── e65a0000.dma-controller/dma/dma2chan1/slave -> ../../../e6590000.usb > ├── e65b0000.dma-controller/dma/dma3chan0/slave -> ../../../e6590000.usb > ├── e65b0000.dma-controller/dma/dma3chan1/slave -> ../../../e6590000.usb > ├── e7300000.dma-controller/dma/dma7chan0/slave -> ../../../e6510000.i2c > ├── e7310000.dma-controller/dma/dma8chan0/slave -> ../../../e6550000.serial > └── e7310000.dma-controller/dma/dma8chan1/slave -> ../../../e6550000.serial > --- > drivers/dma/dmaengine.c | 37 +++++++++++++++++++++++++++++++------ > include/linux/dmaengine.h | 4 ++++ > 2 files changed, 35 insertions(+), 6 deletions(-) > > diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c > index 56a8420c388679d3..617c84cf6800962b 100644 > --- a/drivers/dma/dmaengine.c > +++ b/drivers/dma/dmaengine.c > @@ -60,6 +60,8 @@ static long dmaengine_ref_count; > > /* --- sysfs implementation --- */ > > +#define DMA_SLAVE_NAME "slave" > + > /** > * dev_to_dma_chan - convert a device pointer to its sysfs container object > * @dev - device node > @@ -730,11 +732,11 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name) > if (has_acpi_companion(dev) && !chan) > chan = acpi_dma_request_slave_chan_by_name(dev, name); > > - if (chan) { > - /* Valid channel found or requester needs to be deferred */ > - if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER) > - return chan; > - } > + if (PTR_ERR(chan) == -EPROBE_DEFER) > + return chan; > + > + if (!IS_ERR_OR_NULL(chan)) > + goto found; > > /* Try to find the channel via the DMA filter map(s) */ > mutex_lock(&dma_list_mutex); > @@ -754,7 +756,23 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name) > } > mutex_unlock(&dma_list_mutex); > > - return chan ? chan : ERR_PTR(-EPROBE_DEFER); > + if (!IS_ERR_OR_NULL(chan)) > + goto found; > + > + return ERR_PTR(-EPROBE_DEFER); > + > +found: > + chan->slave = dev; > + chan->name = kasprintf(GFP_KERNEL, "dma:%s", name); > + if (!chan->name) > + return ERR_PTR(-ENOMEM); You will lock the channel... It is requested, but it is not released in case of failure. > + > + if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj, > + DMA_SLAVE_NAME)) > + dev_err(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME); > + if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name)) > + dev_err(dev, "Cannot create DMA %s symlink\n", chan->name); It is not a problem if these fail? > + return chan; > } > EXPORT_SYMBOL_GPL(dma_request_chan); > > @@ -812,6 +830,13 @@ void dma_release_channel(struct dma_chan *chan) > /* drop PRIVATE cap enabled by __dma_request_channel() */ > if (--chan->device->privatecnt == 0) > dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask); > + if (chan->slave) { > + sysfs_remove_link(&chan->slave->kobj, chan->name); > + kfree(chan->name); > + chan->name = NULL; > + chan->slave = NULL; > + } > + sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME); If a non slave channel is released, then you remove the link you have never created? What happens if the link creation fails and here you attempt to remove the failed ones? > mutex_unlock(&dma_list_mutex); > } > EXPORT_SYMBOL_GPL(dma_release_channel); > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h > index 2cd1d6d7ef0fcce5..2804da93e27e114b 100644 > --- a/include/linux/dmaengine.h > +++ b/include/linux/dmaengine.h > @@ -238,10 +238,12 @@ struct dma_router { > /** > * struct dma_chan - devices supply DMA channels, clients use them > * @device: ptr to the dma device who supplies this channel, always !%NULL > + * @slave: ptr to the device using this channel > * @cookie: last cookie value returned to client > * @completed_cookie: last completed cookie for this channel > * @chan_id: channel ID for sysfs > * @dev: class device for sysfs > + * @name: backlink name for sysfs > * @device_node: used to add this to the device chan list > * @local: per-cpu pointer to a struct dma_chan_percpu > * @client_count: how many clients are using this channel > @@ -252,12 +254,14 @@ struct dma_router { > */ > struct dma_chan { > struct dma_device *device; > + struct device *slave; > dma_cookie_t cookie; > dma_cookie_t completed_cookie; > > /* sysfs */ > int chan_id; > struct dma_chan_dev *dev; > + const char *name; > > struct list_head device_node; > struct dma_chan_percpu __percpu *local; > - Péter Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 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